2010 Student Debate Impact of Biological Control, Transgenic Insecticidal Crops, and Global Climate Change on Arthropod Biodiversity Ashfaq A. Sial and Cheri M. Abraham
T
he Entomological Society of America’s (ESA) Committee on Student Affairs organizes student debates at the national meeting of ESA annually. The primary objective of student debates is to foster critical thinking in the next generation of entomologists. Contemporary issues about entomology that are of interest to scientists and the public are usually the subjects of debates. Human activities have led to drastic changes in our environment on local and global scales. Consequently, species are being lost at an unprecedented rate. The expansion of modern chemical-intensive agriculture and global climate change present major threats to arthropod biodiversity. At the same time, the effects of modern agriculture (e.g., pesticide use, biological control, and transgenic insecticidal crops) and global climate change on arthropod biodiversity are often controversial. To better understand the positions on both sides of this issue, “Impact of Biological Control, Transgenic Insecticidal Crops, and Global Climate Change on Arthropod Biodiversity” was selected as the topic of the 2010 ESA Student Debates, held at the 58th Annual Meeting of ESA in San Diego. The three statements that were debated were (1) Increasing natural enemy diversity among arthropods is compatible with the goals of biological control and IPM; (2) Transgenic insecticidal crops will conserve arthropod biodiversity; and (3) Global climate change will have substantial long-term negative effects on arthropod diversity. Three teams (unbiased, pro, and con) were recruited for each of the topics on a first-come, first-served basis. Fred Gould (William Neal Reynolds Professor of Agriculture, Department of Entomology, North Carolina State University) was invited as Distinguished Speaker to introduce the concept of biodiversity.
Biodiversity
Fred Gould William Neal Reynolds Professor of Agriculture, Department of Entomology, North Carolina State University
Images courtesy ARS Image Gallery 94 94
Finding an entomologist who will not defend the general need to preserve biodiversity is a difficult if not impossible task. The aesthetic losses and ethical dilemmas associated with reduction in our planet’s biodiversity are reasonably clear to most professional entomologists and a large portion of the public. Less obvious is how a loss of biodiversity would quantitatively impact specific ecosystem and biological community functions. The topics debated in this article demonstrate some of these uncertain relationships. American Entomologist • Summer 2012
Before delving into the details of the debate, it is worth stepping back a bit to examine the issue of biodiversity more broadly. Most entomologists think they know what it means when someone says “System X has more biodiversity than system Y.” But do we all mean the same thing when we say this? I have presented descriptions of hypothetical insect communities to numerous entomological audiences and asked them which is the most diverse. When presented with community A having three species with 100 individuals of each species and community B having six species with 100 individuals of each species, I always get unanimous agreement that community B is most diverse. When community A is paired with community C that has six species but where one species is represented by 100 individuals and the other five by 10 individuals each, most entomologists judge community C as more diverse than community A; but there are some entomologists who disagree or are not sure. When community A is compared with community D that has six species, one of which has 100 individuals, and the other species are represented by a single individual, most entomologists view community A as being more diverse than D even though D has twice as many species. What value system are entomologists using to make their judgments? In his classical textbook on insect ecology, Price (1997) states that “Diversity may be defined by use of a formula.” Many indices of diversity have been proposed (Pielou 1969, 1975; Poole 1974; Begon et al. 1996; Stiling 1996), but the most commonly used in the past is the Shannon–Weaver diversity index Hʹ, where Hʹ = -Σpi ln(pi).” Here pi is the proportion of individuals in the community made up of individuals of species i. If we now go back to the hypothetical communities and rank their diversity with the Shannon–Weaver formula, we find Hʹ for A, B, C, and D, as 1.10, 1.79, 1.44, and 0.27, respectively. This is a reasonably good match with the answers of entomologists. We must ask the question of whether the Shannon–Weaver index is most commonly used because of its ecological basis compared with other formulae of diversity, or because it fits with our gut feeling about what constitutes biodiversity? Lacking from my hypothetical examples and the Shannon–Weaver index are biological attributes of the species. Would it matter to entomologists if some of the species with 100 individuals were aphids, and the ones with lower numbers were adult grasshoppers? Would it matter if one community only had herbivores and another had an even mix from three trophic levels? Ecologists have long wrestled with these issues, questioning how to measure diversity and how to examine its effects on the functioning of communities and ecosystems. When entomologists ask whether a specific change in an agricultural practice will affect biodiversity or if increased biodiversity will assist pest management, we must carefully define what we mean by biodiversity. Biodiversity can be taxonomic and functional. (There’s species richness and evenness, obviously, but both of these fall under the umbrella of taxonomic diversity.) Functional diversity can be difficult to assess because there’s little agreement over what metrics to use to amalgamate taxa into functional groups. Most of the empirical studies in this area have been conducted by plant ecologists who have found a clear relationship between the number of plant species in a community and the biomass productivity of the ecosystem (Hooper et al. 2005, Balvanera et al. 2006, Ruiz-Jaen and Potvin 2010). They have also found that in some cases diversity is associated with stability of productivity (Tilman et al. 2006). There appears to be a consensus among community ecologists that American Entomologist • Volume 58, Number 2
to predict the effects of species diversity on multitrophic systems, there is a need for data on the functional and mechanistic properties of the species involved (Hooper et al. 2005). In one of the first experimental analyses of the relationship between parasitoid diversity and level of overall parasitism, Force (1974) found that knowing the life history of each parasitoid was critical to understanding how it would affect the rest of the parasitoid community and the level of parasitism, but this was conducted in a mesocosm. As seen in the debate described here, we often lack the information we need for answering important entomological questions about biodiversity in heterogeneous ecosystems.
TOPIC
Increasing natural enemy diversity among arthropods is compatible with the goals of biological control and IPM Unbiased Introduction Joy Newton University of Nevada, Reno
The primary goals of IPM (integrated pest management) are to manage pests within the economic threshold of the crop being produced; reduce hazards to people by reducing or properly applying pesticides; reduce damage to the environment by preventing soil erosion, pesticide runoff and contamination; preserve biodiversity; and protect property by preventing degradation of land production (Torre-Bueno 1989). Economic threshold is the level of a pest population that does not cost economic damage to the crop (Torre-Bueno 1989). When the pest population reaches the economic threshold, control of the pest is necessary (Torre-Bueno 1989). The use of multiple natural enemies as part of biological control within the constraints of IPM is a complex series of biological processes, and the goal is to reduce pest populations more effectively while protecting the crop and the environment. Natural enemies are used in biological control to help reduce abundance or reproductive output of pest populations (TorreBueno 1989). There are three broad categories of natural enemies: parasitoids, predators, or phytophagous weed feeders (Straub et al. 2008). Parasitoids consume (and necessarily kill, or contribute directly to the imminent death of) a single prey item as part of their development to maturity. A predator, in contrast, consumes more than one prey (the pest species) to reach maturity (Torre-Bueno 1989). Phytophagous weed feeders are predators that attack plants viewed as pests. An increase in the diversity abundance of natural enemies may or may not benefit the goals of biological control or IPM because a natural-enemy community has a complex interaction with its target prey and nontarget components of the ecosystem (Ives et al. 2005). In some cases, the natural enemy diversity partitions the pest species and attacks multiple life stages or is more effective in different environmental conditions. In other cases, the diversity of natural enemies results in direct competition between constituent species for the same life stage or environmental conditions (Wilby and Thomas 2002). The degree to which the predator is host-specific (Torre-Bueno 1989) will drive the type of interaction that occurs when a diversity of natural enemies are present. Diversity is a metric that takes into account the relative abundance of each species and the number of species that are present at a site (Ives et al. 2005). To
95
increase diversity, an increase in species richness and homogenizing evenness among taxa at a particular location without decreasing the abundance or removing natural enemies already present at a location might be necessary (Ives et al. 2005). Biological control is the use of a natural enemy to reduce the host population to a lower level than before (Torre-Bueno 1989). Biological control is implemented in one of three ways; namely classical, augmentation, and conservation (Parrella et al. 1992, Landis et al. 2000, Evans 2004). Classical biological control is the importation of a natural enemy into an area where they previously did not occur (Evans 2004). Classical biological control can displace or outcompete natural enemies that are already functioning in the system (Evans 2004), or it can fill an ecological role where native natural enemies could not compete (Vinson 1988). Augmentation biological control is a supplemental release of natural enemies into an area (Parrella et al.1992). Conservation biological control encourages natural enemies to remain or increase in abundance in an area where the pest occurs (Landis et al. 2000). IPM is an environmentally sensitive approach to managing pest species below the economic injury level that relies on a combination of common-sense practices to economically produce crops.
Acknowledgements
I thank Matt Forister for his guidance and support in this endeavor.
▲ Pro Position
Katherine A. Parys, Jennifer Gordon, Sebe Brown, and Blake Wilson Louisiana State University
Agricultural intensification involving the removal of noncrop habitats results in simplification of the landscape, reduced biodiversity and the loss of ecosystem processes (Altieri and Nicholls 2004). Agroecosystems are further simplified by intense chemical control of insects and IPM. IPM incorporates a balance of biological, chemical, and cultural control methods to suppress pest populations while minimizing selection pressure and adverse effects from over-reliance on individual tactics (Metcalf and Luckman 1994). Biological control as a component of IPM reduces reliance on pesticides and can provide long-term sustainability to pest control (Van Driesche et al. 2008). Increasing natural enemy diversity among arthropods is compatible with the goals of biological control and IPM. Biological diversity improves ecosystem function by increasing nutrient cycling, regulating microclimate, encouraging soil hydration, and controlling agricultural pests, which together have been credited as saving an estimated $4.5 billion in revenue losses annually (Altieri 1993). Persistence of these ecosystem services depends on the maintenance of biodiversity within the system (Bianchi et al. 2006, Straub et al. 2008). Multiple natural enemies enhance overall ecosystem stability and resource utilization. Increasing diversity leads to a greater number of trophic links within a community and a more stable ecosystem (Altieri 1993, Cardinale et al. 2003, Snyder et al. 2008). Management practices which influence herbivore dynamics within agroecosystems decrease reliance on any one tactic, reducing selection pressure and the chance of secondary pest outbreaks (Altieri and Nicholls 2004). In communities with multiple natural enemies, the most efficient predator or parasitoid usually dominates resource acquisition within an ecosystem (Hackett-Jones et al. 2009). High diversity increases the chance that the most effective natural enemy is present within 96
the system, and competitive exclusion regulates populations of less effective natural enemies (Tylianakis et al. 2006). If superior control is provided from a single biological control species, then this species will become more prevalent; however, it does not necessarily eliminate other natural enemies. Thus, increased diversity of natural enemies may lead to greater resource consumption (pest suppression) via an increased probability that particularly effective predator species will be present and contribute disproportionately to pest suppression through resource partitioning and niche differentiation. Increased diversity by natural enemies generally enhances pest suppression through interspecific facilitation or complementary resource use (Straub et al. 2008). Species complementarity results from resource partitioning, such as natural enemies that attack different life stages of prey or stratify populations by spatial differentiation within the microhabitat (Wilby and Thomas 2002, Cardinale et al. 2003, Hackett-Jones et al. 2009). All of these can lead to higher levels of resource consumption and thus greater pest suppression. Increasing the diversity of natural enemies is compatible with IPM and biological control by using ecological principles in the development of successful pest management programs. Utilizing multiple, host-specific biological control agents supports the fundamental goal of IPM by reducing reliance on a single pest control tactic. Similarly, increasing biodiversity is compatible with the goals of biological control by providing natural pest regulation while reducing selection pressure from the use of insecticides. Thus, increasing natural enemy diversity supports IPM and biological control.
Acknowledgements
We thank our advisers Seth Johnson and Gene Reagan for their guidance and support.
▼ Con Position
Shaku Nair, Whitney Boozer, Rachel Bottjen, Sonja Brannon, and Stephanie Weldon. University of Georgia
Biocontrol is a key component of IPM. It has been argued that increasing natural enemy diversity within agricultural systems will maximize control of insect pests. More recent literature shows minimal support for a correlation between natural enemy diversity and the efficacy of biocontrol. Denoth et al. (2002) summarized the results of 108 biocontrol projects relating the number of natural enemies released to their successful establishment and control of pest species. Of all the multiple-agent projects assessed, only 47% of released enemies became successfully established, compared with 75% in single-agent projects. Ehler and Hall (1982) found that the rate of establishment of exotic enemies was inversely related to the number of species released simultaneously. Additionally, Denoth et al. (2002) determined that in 56% of the successful multiple agent release projects, a single agent was responsible for establishing control. Finke and Denno (2004) observed that decreasing natural enemy diversity improved plant biomass production in marsh systems, and their previous work suggests that the effect would likely be magnified in agricultural systems (Finke and Denno 2003). According to Rodriguez and Hawkins (2000), only a single key species is required for strong top-down control in the majority of parasitoid biocontrol programs. This was supported by their own study, which found no relationship between parasitoid species rich
American Entomologist • Summer 2012
ness and increased parasitism. Finke and Denno (2004) combined wolf spiders Hogna modesta (Thorell) with mirid bugs (Tytthus vagus Knight) to suppress a scale insect pest; instead of cooperative consumption of the pest species, they found that wolf spiders preferentially fed on the active mirids, relaxing the herbivore suppression and allowing a surge in the pest population. Yet another example of predator–predator interactions that negatively affect biocontrol is reported by Rosenheim et al. (1999); multiple generalist predators preferentially preyed on each other rather than the target insects. It is important to state here that classical biocontrol theory for predator–prey interactions has been traditionally based on three discrete trophic levels of plant, herbivore, and predator. The release of multiple agents at the same trophic level creates a new paradigm of interactions that become of paramount importance. Greater diversity may also lead to interference and displacement of biocontrol agents. Zhou et al. (2010) demonstrated a case where competition among parasitoids consistently drove one or more species away. This becomes especially important when considering exotic enemies, and their ability to drive out native natural enemies. Ehler and Hall (1982) discussed that displacement led to elimination of superior control agents. In cases where displacement did not occur, interspecific competition could still negatively affect biocontrol. Bográn et al. (2002) provide an example in which the most effective parasitoid in pure culture became severely less successful in mixed culture. Biocontrol has a high (80–90%) failure rate and often carries unanticipated ecological risks (Lockwood 1993, Louda et al. 1997). Simberloff and Stiling (1996) reported numerous biocontrol introductions that adversely affected nontarget native species. In the notorious case of the multicolored Asian lady beetle [Harmonia axyridis (Pallas)], this introduced predator attacked fruit crops and affected wine quality (Kovach 2004). Greater diversity may not be cost-effective. Every introduced insect has costs associated with rearing, research and release. The maintenance of multiple refugia also requires resources, land, and time. Furthermore, there are the risks of refugia harboring pests and pathogens. Araj et al. (2006) discovered that floral resources for a desired parasitoid benefited its hyperparasitoid even more. In summary, although biodiversity is important in natural systems, increasing diversity in agricultural systems is often unpredictable, and releases are irreversible. Therefore, focusing on one or few biocontrol agents is preferable to acting on the erroneous assumption that increasing enemy diversity will maximize control of pest populations.
Acknowledgements
We thank our adviser Paul Guillabeau for his guidance, invaluable feedback, and support.
TOPIC
Transgenic insecticidal crops will conserve arthropod biodiversity Unbiased Introduction Serena Gross Purdue University
Transgenic insecticidal crops are genetically modified organisms used to minimize loss caused by pest insects. Transgenic insecticidal American Entomologist • Volume 58, Number 2
crops potentially could conserve arthropod biodiversity, by reducing the use of broad-spectrum pesticides, which could reduce the mortality of natural enemies and beneficial arthropods (Wraight et al. 2000). Transgenic insecticidal crops might not conserve biodiversity because of effects on nontarget arthropods and problems with secondary pest insects. The most common insecticidal protein currently used in transgenic crops is from the bacterium Bacillus thuringiensis Berliner (Li et al. 2007). Bacillus thuringiensis (Bt) toxins kill only a narrow range of species; the insects it targets depends on the particular crystal (Cry) proteins encoded in the specific crop (Li et al. 2007). Much testing has been done to determine the effects of transgenic crops on nontarget arthropods; there is still question as to their effects on biodiversity (Lovei et al. 2009). Species richness is commonly used to describe biodiversity (Aviron et al. 2009). Biodiversity is beneficial in agricultural ecosystems because of the ecosystem services provided, such as nutrient cycling, pollination, and pest regulation (Garcia and Altieri 2005). Transgenic crops may help to decrease contamination of groundwater, soil, and air by broad-spectrum insecticides (Wraight et al. 2000). It is also possible that reducing the use of broad-spectrum insecticides could increase the density of natural enemies (Velkov et al. 2005). Transgenic plants are tested to determine what affect they might have on beneficial arthropods, but only a small amount of the arthropods that could be affected can be tested (Lovei et al. 2009). It is impossible to test the effects of transgenic insecticidal crops on all arthropod species that may possibly be affected by the introduction of these crops (Aviron et al. 2009). There is often question as to which arthropod species should be tested when determining whether transgenic insecticidal crops are safe for use. Common species are more detectable but are often less sensitive to environmental disturbances, while rare or endangered species are harder to detect in the field, their low abundance may cause problems in achieving statistically significant results (Aviron et al. 2009). Fewer studies have been done on the effects of transgenic insecticidal crops on arthropods other than insects (Lovei et al. 2009) because monitoring biodiversity is expensive and time consuming (Schmeller and Henle 2008). There is concern with the chance that transgenic genes flowing to wild relatives could affect the nontarget arthropods associated with those plants (Andow and Zwahlen 2006). Experiments have also found that though the transgenic insecticidal crop lowers the numbers of the primary pest insect, the numbers of a secondary pest insect that is not targeted by the transgenic insecticidal crop can increase (Velkov et al. 2005). Predator levels have been found to be higher in Bt cotton fields than in non-Bt cotton fields that have been treated with insecticides (Velkov et al. 2005). However, it is possible that natural enemies feeding on nontarget herbivores may come into contact with more Bt toxins due to the toxins not binding in the gut of the nontarget herbivores (Garcia and Altieri 2005). Another possible issue is that of pest insect resistance to transgenic insecticidal crops, which has been reported in some organisms (Singh 2005), and could increase the need for insecticides. Biodiversity loss can be measured by the loss of individual species, groups of species, or decreases in the number of organisms (Ammann 2005). Given the impact that transgenic insecticidal crops could have on biodiversity, and the factors involved with determining the effect that these crops have on biodiversity, the debate will likely continue for some time.
97
Acknowledgements I thank Ralph E. Williams for his guidance and feedback.
▲ Pro Position
Maggie Paxson, Wendy Helmey-Hartman, Gaurav Goyal, and Harsimran Gill University of Florida
When considering the prospects for modern agriculture in an increasingly technological society, the topic of transgenic insecticidal crops often appears as a “cure-all” for agricultural issues. Although transgenic insecticidals such as Bt crops (named for the insecticidal transgene that regulates production of toxins from Bacillus thuringiensis) have not been perfected in all cases for the commercial market, their potential to improve agricultural ecology and revolutionize the ways we conduct pest management make them a vital topic for further study. In asking the question of whether or not these crops will preserve biodiversity, we assert that they do because they cause fewer detrimental effects to arthropod biodiversity than the status quo (conventional insecticide spray programs). When comparing Bt and other transgenic insecticidal crops with current methods of pest management, we find that ecological impacts (including biodiversity) caused by transgenics pale in comparison to the damage done by broad-spectrum insecticides. The affirmative plan is two-pronged in its support of transgenic insecticidal crops. In field scenarios where Bt and other transgenics have been shown to be viable, successful, and non-damaging forms for pest management such as in corn, cotton, and eggplant (Cattaneo et al. 2006, Arpaia et al. 2007), we advocate the use of these crops. In field conditions where Bt may be damaging or detrimental on the whole, we advocate further research of arthropod–Bt crop interactions to continuously improve this burgeoning technology. We base our assertions on four reasons. First, numerous studies have shown that in most cases, transgenic insecticidals do less overall damage to beneficial arthropods (Chen et al. 2008, Farinos et al. 2008) and neighboring communities than the broad-spectrum pesticide alternatives (Velkov et al. 2005). In truth, the few laboratory studies that show Bt as a force more damaging than pesticides can be easily countered by proposing a slightly different transgenic cultivar, e.g., one that does not express the Bt toxin in the plant’s pollen (Yao et al. 2008). These plants also pose a lowered risk to neighboring environments and ecosystems such as scrub areas or nearby wilderness zones (Icoz and Stotzky 2008). Second, transgenic insecticidal plants offer many benefits over the current alternative of pesticides that make Bt and other crop cultivars a practical preservation method for biodiversity (Marvier 2001, Ferry et al. 2006). Bt crops require fewer maintenance costs than pesticides and require only an initial planting rather than multiple applications (Wraight et al. 2000). In addition, fears that Bt or other transgenes may jump from one plant species to another are largely speculative with little true risk. Third, non-transgenic alternative strategies to the status quo are largely infeasible on a large-scale production level and offer little ability for commercial growers to preserve biodiversity and turn a profit (Marvier 2001). The sad reality of agriculture is that control will always be needed, so a low-maintenance, pragmatic control method must be preferentially selected over the wide-scale environmental destruction brought about by broad-spectrum insecticides (Ammann 2005, Velkov et al. 2005). 98
Our final argument synthesizes the debate, stating that pest management options must be viewed with an on-balance consideration (Wraight et al. 2000). Dangerous transgenics are not released into the wild without scientific investigation (Marvier 2001, Arpaia et al. 2007). With the proper research advocated by the affirmative plan and denied by the negative side, we can work toward a pest management strategy that does more good than harm to the agricultural environment it seeks to mold. Yes, Bt crops damage pestiferous insect diversity; and yes, they may confer slight damage to predators of these insects; but all of this must be viewed through the lens of current pest control methodology: a policy of blanket insecticidal spray with little regard to the affected environment within and outside of our agriculture. When taking all of these arguments into consideration, we may only affirm that transgenic insecticidal crops will conserve arthropod biodiversity in comparison to the status quo.
Acknowledgements
We thank our adviser Gregg Nuessly for his guidance, invaluable feedback, and support.
▼ Con Position
Melanie Smith1 and Isabelle Vea2 1 Columbia University; 2Richard Gilder Graduate School at American Museum of Natural History
Although transgenic insecticidal (TI) crops are touted for their ability to decrease use of wide-spectrum pesticides, target specific pest insect groups, and boost final yield production (Sharma and Ortiz 2000), we argue that their net impact will harm arthropod genetics, species, and ecosystem diversity in that they • increase mortality of nontarget arthropods, • possibly increase pesticide use and toxins in TI crops with insect resistance, • disrupt trophic groups and other biological interactions, and • negatively affect other ecosystems linked to agricultural settings.
Bt toxins, the most commonly used lethal ingredient of TI crops, are proteins designed to target different groups of organisms (Clark et al. 2005). For instance, Cry1, Cry2, and Cry9 are efficient in Lepidoptera and Cry3 in Coleoptera. Several studies, however, have shown increased mortality in insects outside the target group (Andow and Zwahlen 2006); the insecticide is not as specific as previously thought and therefore can harm species diversity. The toxin is expressed in many parts of the plant and has many conduits to nontarget insects, a few of which are important to arthropod conservation. For example, when Bt toxins appear in pollen, they have lethal and sublethal effects in black swallowtail (Papilio polyxenes F.) and monarch butterfly [Danaus plexippus (L.)] (Hansen Jesse and Obrycki 2000, Zangerl et al. 2001, Groot and Dicke 2002). Field and laboratory experiments show that the resistance of genetically modified (GM) crops to target pests is short-lived, which will likely result in the application of stronger pesticides and the creation of Bt crops containing an armada of different toxins (Stewart et al. 2001, Schuler et al. 2004). Both of these responses not only negate the expected decrease in pesticide use among Bt crops but will instead lead to increased mortality caused by more potent crops. Overall, genetic biodiversity of nontarget arthropods will decrease. Interactions between TI crops and target and nontarget arthro
American Entomologist • Summer 2012
pods can disrupt ecological functional groups, trophic relationships, and controls, subsequently decreasing species and ecosystem biodiversity. Specifically, Bt toxins have been shown to move across trophic levels and disrupt health and behavior with deleterious effects. The green lacewing [Chrysoperla carnea (Stephens)], which is an important predator of pests, showed higher mortality, prolonged developmental time, and decreased weight when fed prey raised on Bt-sprayed corn (Dutton et al. 2002). In one of the few multigenerational studies, adult ladybird beetle [Propylaea japonica (Thunberg)] reared from parents that preyed on aphids fed with Bt corn had higher levels of malformations and an altered phenology (Zhang et al. 2009). Parasitoids raised on Bt corn experienced high levels of mortality because their hosts died prior to emergence (Schuler et al. 2004). Bt toxins do not cease to harm the biodiversity of arthropods when the TI crops are harvested. After the growing season, crop remains decompose in the soil, allowing Bt toxins to interact with soil organisms. Several studies have shown that the toxins persist in the soil for several months and that the TI crops decompose more slowly than other crops (Flores et al. 2005, Janot et al. 2010). As a consequence, nontarget insects in the soil are also exposed to Bt toxins, disrupting the normal process of decomposition and recycling of organic matter into beneficial nutrients that could otherwise improve crop growth. This harms ecosystem functioning crucial to arthropods. Because of the lethal and sublethal effects of TI crops on arthropods and the poorly understood mechanisms of these effects upon the ecosystem more broadly, we believe Bt crops will not lessen the impact of agriculture on native biodiversity. Insects in our current environment are exposed to enormous environmental pressures, and the introduction of further lethal components will only increase insect mortality and the specter of species extinction. We call for increased and conclusive studies of risk assessment methods before further implementing these crops in the industrial scale.
Acknowledgements
We thank our faculty adviser James Danoff-Burg from Columbia University’s Center for Environment, Economy, and Society, for his invaluable feedback and support. We also appreciate the support from our programs, Columbia University’s Ecology, Evolution, and Environmental Biology Department and the Richard Gilder Graduate School.
TOPIC
Global climate change will have substantial long-term negative effects on arthropod diversity Unbiased Introduction Kathleen Schnaars-Uvino The Graduate Center–CUNY
Global climate change (GCC) is occurring at an unprecedented rate. That it is already having an effect on species, communities, and phenologies has been documented. Temperatures over the past 100 years have risen by approximately 0.6 °C with a predicted increase of between 1.4 and 5.8 °C by 2100 (Chown et al. 2007, Visser 2008). Atmospheric carbon will rise over the same period. Although increase in precipitation, Ultraviolet B (UVB) penetration, and extreme events (e.g. flooding, storms, and drought) are all predicted, there is less certainty about the extent of these changes (Bale et al. 2002). The American Entomologist • Volume 58, Number 2
question of magnitude of the ecological effects due to GCC centers on whether species will be able to adapt fast enough to keep up with a changing environment (Visser 2008). During the last warming event, the Paleocene–Eocene Thermal maximum 53 million years ago, arthropod diversity increased in predatory, parasitic, saprophagous and phytophagous guilds. Arthropods enjoy a suite of characteristics that enables them to quickly occupy new niches and to be the most successful organisms on the planet. These characteristics include flexible reproductive strategies and reproductive success in warmer climates. Some predict that the long-term increase in mean global temperature will favor arthropods because of this suite of flexible life traits. These and other characteristics could serve arthropods well in the face of GCC (Wilf and Labandeira 1999). During the Paleocene–Eocene event, however, the rate of temperature increase was slower than it is today, and there were no anthropogenic factors facing arthropods to thwart their ability to adapt to the new environment. These factors may confound the very characteristics that contribute to arthropod success. Although mean global temperature is critical to arthropods, other factors affect species’ range and changes in their range in complex ways. Some of these are natural oscillations underlying long-term trends and photoperiod (Visser 2008). Phenology is the timing of seasonal activities of plants and animals alike and is the simplest process used to track changes in the ecology of a species in response to climate change (Walther et al. 2002). However, there is no reason why the phenology of different trophic levels will shift at the same time. If a species’ phenology is shifting at a different rate than the other species within its community, this will lead to mistiming of its seasonal activities, also known as a mismatch in phenology. Range expansion of southern populations into northern areas has occurred (Walther et al. 2002). Some researchers posit that they may have genotypes better adapted to warmer conditions that account for their success. However, this does not take into account that different photoperiod and/or rainfall occur in the more northern areas, and photoperiod plays a crucial role in seasonal timing of arthropods (e.g. diapause) (Bale et al. 2002, Botkin et al. 2007) Global climate change is a critical factor when looking at, or trying to predict, future diversity. Factors that can affect species range and changes in their range interact in complex ways. This is further complicated by recurring pitfalls in measuring biodiversity and/or the absences of a way to measure species shifts in response to GCC (Gotelli and Colwell 2001, Visser and Both 2005). The challenge of the two teams that follow will be to do just that—predict future biodiversity of arthropods based upon GCC.
Acknowledgements
I thank my faculty adviser Robert Rockwell for his guidance, invaluable feedback, and support.
▲ Pro Position
Tom G. Bentley, Margaret R. Douglas, Ian M. Grettenberger, Elina L. Niño, C. Sheena Sidhu, and Jason D. Smith The Pennsylvania State University
Arthropod diversity stands to endure great losses as a result of the ongoing climate change event. Earth’s temperature has increased 0.6 °C in the past century and is predicted to increase another 1.4–5.8 °C
99
by 2100 (IPCC 2002). Although any climatic shift presents challenges to life on Earth, today’s arthropods must respond to these challenges in the context of a landscape dominated by human activity. Given this unprecedented scenario, the current climate change event will cause long-lasting declines in arthropod diversity. Stressors stemming directly from global climate change and negatively affecting arthropods include increased water and terrestrial surface temperatures, decreased water oxygen content, and increased frequency of extreme events such as droughts, floods, and fires (IPCC 2002). In addition, divergent responses to changing seasonal cues will often result in asynchrony between arthropods and the host species they rely on for survival (Visser and Holleman 2001, Bale et al. 2002). Faced with this suite of stressors, arthropods must move, adapt, or perish. Movement to climate-appropriate habitat will be impossible for many arthropod populations. Some minute, flightless, or sedentary species will be incapable of relocating rapidly enough (Warren et al. 2001), and many mobile species will face irreconcilable circumstances. For instance, arthropods in isolated ecosystems—such as mountaintops, islands, and caves—are made vulnerable by the great distances, physical barriers, or uninhabitable regions that often obstruct routes to new suitable habitat (Chevaldonne and Lejeusne 2003, Parmesan 2006). In addition to these natural impediments, urban and agricultural development can similarly restrict the movement of many arthropods across the landscape (Travis 2003). Arthropods that do relocate successfully might find that their climate envelope has shifted to land dedicated to human use, or that their necessary hosts have failed to move with them (Bale et al 2002, Robinet and Roques 2010). Therefore, many arthropod populations will be unable to escape the adverse effects of our rapidly changing climate through movement. Adaptation, another strategy for coping with climate change, is also beset with serious limitations. Habitat isolation, fragmentation, and destruction have already depleted species’ genetic resources by diminishing populations and restricting gene flow (Hughes et al. 1997, Warren et al. 2001, Walther et al. 2002, Travis 2003). In this compromised state, arthropods must respond simultaneously to climate change stressors and other human-mediated challenges, such as the heightened success of invasive species in climate-stressed environments (Robinet and Roques 2010), and additional habitat loss as humans respond to changing weather patterns (Rosenzweig et al. 2007). Finally, the rate of modern climate change far outpaces the rate of prior events, placing increased demand on arthropod genetic resources (Davis and Shaw 2001). Not all arthropod populations will adapt fast enough to endure. Arthropods are certainly one of the most numerous, diverse, and adaptable groups of organisms the world has known, but even their adaptability has limits. Unfortunately, many of Earth’s most diverse ecosystems are also the most vulnerable to climate change stressors. The tropics, for example, are home to species living within extremely narrow thermal tolerances (Deutsch et al. 2008). Escape for these arthropods will be hindered by the deserts and human settlements that border most tropical regions (IPCC 2002, Thomas et al. 2004). Other biodiversity hotspots such as coral reefs and some Pacific islands are likely to suffer similar losses because of their distinctness and isolation (Myers et al. 2000, IPCC 2002). Considering the essential functions that arthropods perform in almost every ecosystem, climate-driven losses of arthropod diversity will have far-reaching consequences for life on Earth. 100
Acknowledgements We thank our faculty adviser Mike Saunders for his time, advice, and humor, which he provided in abundance as we prepared for the debate. We also thank the Department of Entomology at the Pennsylvania State University for funding that enabled our participation in the 2010 ESA debates.
▼ Con Position
S. Addison Barden, Charles D. R. Stephen, Prithwiraj D. Das, and Esther N. Ngumbi Auburn University
Over millions of years of evolution, arthropods have acquired uniquely favorable morphological and physiological adaptations, making them the most successful organisms on Earth (Andrew and Hughes 2005). As temperatures increase around the planet, arthropod activity will correspondingly increase. These increases will include movement to find new food sources and suitable mates and to escape predation, resulting in increased dispersal and migration (Rohde 1992). Increases in temperature also give physiological benefits to arthropods, such as decreases in developmental time, resulting in greater number of generations per year, which in turn speeds speciation rates (Morrison et al. 2005). Arthropods are biologically primed for rapid speciation. As current tropical regions migrate poleward, arthropod diversification will certainly follow suit (Wilf and Labandeira 1999, Bradshaw and Holzapfel 2006). This will bring about an increase in plant diversity in temperate regions, which will result in novel food sources. These newly opened niches will be rapidly filled by arthropods as they follow their host plants poleward (Wilf 2008). Selection pressures from these newly acquired niches will cause migrating arthropods to undergo adaptive radiations. We have a terrific opportunity to learn from a past warming event: the Paleocene–Eocene Thermal Maximum (PETM). This took place 56 million years ago and was a time when the Earth went through a massive short-term increase in mean temperatures (DeLucia et al. 2008). Fossils from this period serve as a great historical reference point to compare against current global climate change (Wilf and Labandeira 1999). During the PETM, substantial poleward expansion and diversification of arthropods occurred, coinciding with adaptive radiations of plants and driving evolution of specialized herbivores (Wilf 2008). In addition to the past events, contemporary long-term evidence illustrates that arthropods are currently benefiting from global climate change. Decades of research in the Atlantic Ocean have found that phytoplankton and zooplankton populations are increasing their range and diversity in response to sea surface temperature increases (Rombouts et al. 2009, Beaugrand et al. 2010). In addition to this, a 25-yr study in Europe noted significant range increases in nine major groups of arthropods, in altitude and latitude (Hickling et al. 2006). As a result of arthropods acquiring these available niches, adaptive radiation occurs from new selection pressures. For example, mosquitoes have been found to be expanding their range poleward in response to higher mean temperatures (Bradshaw and Holzapfel 2006). As a result of these newly acquired niches, these mosquitoes experience changes in photoperiods that are fueling unique genetic adaptations (Bradshaw and Holzapfel 2006). Data of plants and arthropods in the Canary and Hawaiian Islands show that there is a
American Entomologist • Summer 2012
direct positive relationship between species diversity and the rate of speciation (Emerson and Kolm 2005). Global climate change is a relatively slower process and shortterm studies may not be useful to understand its impacts. The literature cited by the opponent team attempts to create extrapolations from mammals, birds, and amphibians, and then somehow relate them to arthropods. For example, Walther et al. (2002) examined a single species of Lepidoptera and then lumped this species with other non-arthropod taxa. It is incorrect to draw inferences on arthropod diversity from this study. Similarly, Thomas et al. (2004) attempted to create background extinction rates based on the International Union for the Conservation of Nature’s Red List, which is highly biased toward vertebrates. The reaction of the spotted owl to global climate change cannot be considered equivalent to that of the spotted cucumber beetle (Diabrotica undecimpunctata howardi Barber). In summary, historical events show that arthropods will not only benefit but will thrive during global warming events. Contemporary long-term data show that current warming events are not only favoring terrestrial arthropods but marine arthropods as well. Millions of years of evolutionary adaptations have equipped arthropods with the structures and mechanisms to overcome adversity. With this ability to overcome adversity, arthropods will thrive during favorable periods such as during global warming, thus remaining the most successful and diverse group of organisms on the planet.
Acknowledgements
We thank our faculty adviser David Held for his guidance, invaluable feedback, and support.
Acknowledgements
Special thanks are extended to Thomas E. Reagan at Louisiana State University for his continued dedication and guidance of the student debates. He has contributed greatly to the organization of the debates and to manuscript preparation over the past 12 years. We also thank our judges Steven Arthurs, Joseph Patt, Tahir Rashid, Anne Nielsen, Brenda Oppert, Rajagopalbabu Srinivasan, Ann Hajek, Mike Parrella, and Mary Purcell-Miramontes for volunteering their time to help us select the winning teams. We also thank G. David Buntin (The University of Georgia) and Shawn A. Steffan (University of Wisconsin–Madison) for critically reviewing this manuscript and providing helpful suggestions.
References Cited
Altieri, M. 1993. Ethnoscience and biodiversity: key elements in the design of sustainable pest management systems for small farmers in developing countries. Agric. Ecosys. Environ. 46: 257–272. Altieri, M. A., and C. I. Nicholls. 2004. Biodiversity and pest management in agroecosystems, 2nd ed. CRC Press, Boca Raton, FL. Ammann, K. 2005. Effects of biotechnology on biodiversity: herbicidetolerant and insect-resistant GM crops. Trends Biotechnol. 23: 388–394. Andow, D. A., and C. Zwahlen. 2006. Assessing environmental risks of transgenic plants. Ecol. Lett. 9: 196–214. Andrew, N. R., and L. Hughes. 2005. Arthropod community structure along a latitudinal gradient: implications for future impacts of climate change. Aust. Ecol. 30: 281–297. Araj, S. A., S. D. Wratten, A. J. Lister, and H. L. Buckley. 2006. Floral nectar affects longevity of the aphid parasitoid Aphidius ervi and its hyperparasitoid Dendrocerus aphidum. N.Z. Plant Prot. 59: 178–183. Arpaia, S., G. M. DiLeo, M. C. Fiore, J. E. U. Schmidt, and M. Scardi. 2007. Composition of arthropod species assemblages in Bt-expressing and near isogenic eggplants in experimental fields. Environ. Entomol. 36: 213–227. American Entomologist • Volume 58, Number 2
Aviron, S., O. Sanvido, J. Romeis, F. Herzog, and F. Bigler. 2009. Casespecific monitoring of butterflies to determine potential effects of transgenic Bt-maize in Switzerland. Agric. Ecosyst. Environ. 131: 37–144. Bale, J. S., G. J. Masters, I. D. Hodkinson, C. Awmack, T. M. Bezemer, V. K. Brown, J. Butterfield, A. Buse, J. C. Coulson, J. Farrar, J. E. G. Good, R. Harrington, S. Hartley, T. H. Jones, R. L. Lindroth, M. C. Press, I. Symrnioudis, A. D. Watt, and J. B. Whittaker. 2002. Herbivory in climate change research: direct effects of rising temperature on insect herbivores. Global Change Biol. 8: 1–16. Balvanera, P., A. B. Pfisterer, N. Buchmann, J. S. He, T. Nakasizuka, D. Raffaeli, and B. Schmid. 2006. Quantifying the evidence for biodiversity effects on ecosystem functioning and services. Ecol. Lett. 9: 1146–1156. Beaugrand, G., M. Edwards, and L. Legendre. 2010. Marine biodiversity, ecosystem functioning, and carbon cycles. 2010. Proc. Natl. Acad. Sci. USA. 107: 10120–10124. Begon, M., J. L. Harper, and C. R. Townsend. 1996. Population ecology: A unified study of animals and plants, 3rd. ed. Blackwell Scientific, Oxford, UK. Bianchi, F. J., C. J. Booij, and T. Tscharntke. 2006. Sustainable pest regulation in agricultural landscapes: review on landscape composition, biodiversity and natural pest control. Proc. R. Soc. B. 273: 1715–1727. Bográn, C. E., K. M. Heinz, and M. A. Ciomperlik. 2002. Interspecific competition among insect parasitoids: field experiments with whiteflies as hosts in cotton. Ecology 83: 653–668. Botkin, D. B., H. Saxe, M. B. Araujo, R. Betts, R. H. W. Bradishaw, T. Cedhagen, P. Chesson, T. P. Dawson, J. R. Etterson, D. P. Faith, S. Ferrier, A. Guisan, A. S. Hansen, D. W. Hilbert, C. Loehle, C. Margules, M. New, M. J. Sobe and D. R. B. Stockwell. 2007. Forecasting the effect of global warming on biodiversity. Bioscience, 57: 227-236. Bradshaw, W. E., and C. M. Holzapfel. 2006. Evolutionary response to rapid climate change. Science 312: 1477–1478. Cardinale, B. J., C. T. Harvey, K. Gross, and A. R. Ives. 2003. Biodiversity and biocontrol: emergent impacts of a multi-enemy assemblage on pest suppression and crop yield in an agroecosystems. Ecol. Lett. 6: 857–865. Cattaneo, M. G., C. Yafuso, C. Schmidt, C. Y. Huang, M. Rahman, C. Olson, C. Ellers-Kirk, B. J. Orr, S. E. Marsh, L. Antilla, P. Dutilleu, and Y. Carriere. 2006. Farm-scale evaluation of the impacts of transgenic cotton on biodiversity, pesticide use, and yield. Proc. Natl. Acad. Sci. USA 103: 7571–7576. Chen, M., J. Z. Zhao, A. M. Shelton, J. Cao, and E. D. Earle. 2008. Impact of single-gene and dual-gene Bt broccoli on the herbivore Pieris rapae (Lepidoptera: Pieridae) and its pupal endoparasitoid Pteromalus puparum (Hymenoptera: Pteromalidae). Transgenic Res. 17: 545–555. Chevaldonne, P., and C. Lejeusne. 2003. Regional warming-induced species shift in north-west Mediterranean marine caves. Ecol. Lett. 6: 371–379. Chown, S. L., S. Slabber and M. A. McGeoch. 2007. Phenotypic plasticity mediates climate change responses among invasive and indigenous arthropods. Proc. R. Soc. B. 274: 2531–2537. Clark, B. W., T. A. Phillips, and J. R. Coats. 2005. Environmental fate and effects of Bacillus thuringiensis (Bt) proteins from transgenic crops: a review. J. Agric. Food Chem. 53: 4643–4653. Davis, M. B., and R. G. Shaw. 2001. Range shifts and adaptive responses to Quaternary climate change. Science 292: 673–679. DeLucia, E. H., C. L. Casteel, P. D. Nabity, and B. F. O’Neill. 2008. Insects take a bigger bite out of plants in a warmer, higher carbon dioxide world. Proc. Natl. Acad. Sci. 105: 1781–1782. Denoth, M., L. Frid, and J. H. Myers. 2002. Multiple agents in biological control: improving the odds? Biol. Control 24: 20–30. Deutsch, C. A., J. J. Tewksbury, R. B. Huey, K. S. Sheldon, C. K. Ghalambor, D. C. Haak and P. R. Martin. 2008. Impacts of climate warming on terrestrial ectotherms across latitude. Proc. Natl. Acad. Sci. 105: 6668–6672. Dutton, A., H. Klein, J. Romeis, and F. Bigler. 2002. Uptake of Bt-toxin by herbivores feeding on transgenic maize and consequences for the predator Chrysoperla carnea. Ecol. Entomol. 27: 441–447. Ehler, L. E., and R. W. Hall. 1982. Evidence for competitive exclusion of introduced natural enemies in biological control. Environ. Entomol. 11: 1–4. Emerson, B. C., and N. Kolm. 2005. Species diversity can drive speciation. Nature 434: 1015–1017. Evans, E. W. 2004. Habitat displacement of North American ladybirds by 101
an introduced species. Ecology 85: 637–647. Farinos, G. P., M. de la Poza, P. Hernandez-Crespo, F. Ortego, and P. Castanera. 2008. Diversity and seasonal phenology of aboveground arthropods in conventional and transgenic maize crops in Central Spain. Biol. Control 44: 362-371. Ferry, N., E. A. Mulligan, C. N. Stewart, B. E. Tabashnik, G. R. Port, and A. M. R. Gatehouse. 2006. Prey-mediated effects of transgenic canola on a beneficial, nontarget, carabid beetle. Transgenic Res. 15: 501–514. Finke, D. L., and R. F. Denno. 2004. Predator diversity dampens trophic cascades. Nature 429: 407–410. Flores, S., D. Saxena, and G. Stotzky. 2005. Transgenic Bt plants decompose less in soil than non-Bt plants. Soil Biol. Biochem. 37: 1073–1082. Force, D. M. 1974. Ecology of insect host–parasitoid communities. Science 184: 624–632. Gotelli, N. J., and R. K. Colwell. 2001. Quantifying biodiversity: procedures and pitfalls in the measurement and comparison of species richness. Ecol. Lett. 4: 379–391. Groott, A. T., and M. Dicke. 2002. Insect-resistant transgenic plants in a multi-trophic context. Plant J. 31: 387–406. Hackett-Jones, E., C. Cobbold, and A. White. 2009. Coexistence of multiple parasitoids on a single host due to differences in parasitoid phenology. Theor. Ecol. 2(1): 19–31. Hansen Jesse, L. C., and J. J. Obrycki. 2000. Field deposition of Bt transgenic corn pollen: lethal effects on the monarch butterfly. Oecologia 125: 241–248. Hickling, R., D. B. Roy, J. K. Hill, R. Fox, and C. D. Thomas. 2006. The distributions of a wide range of taxonomic groups are expanding polewards. Global Change Biol. 12: 450–455. Hooper, D. U., F. S. Chapin, J. J. Ewel, A. Hector, P. Inchausti, S. Lavorel, J. H. Lawton, D. M. Lodge, M. Loreau, S. Naeem, B. Schmid, H. Setala, A. J. Symstad, J. Vandermeer, and D. A. Wardle. 2005. Effects of biodiversity on ecosystem functioning: A consensus of current knowledge. Ecol. Monogr. 75: 3–35. Hughes, J. B., G. C. Daily, and P. R. Ehrlich. 1997. Population diversity: its extent and extinction. Science 278: 689–692. Icoz, I., and G. Stotzky. 2008. Fate and effects of insect-resistant Bt crops in soil ecosystems. Soil Biol. Biochem. 40. IPCC (Intergovernmental Panel on Climate Change). 2002. Climate change and biodiversity. IPCC, Geneva, Switzerland. Ives, A. R., B. J. Cardinale, and W. E. Snyder. 2005. A synthesis of subdisciplines: predator–prey interactions, and biodiversity and ecosystem functioning. Ecol. Lett. 8: 102–116. Janot, J. -M., M. Boissiere, T. Thami, E. Tronel-Peyroz, N. Helassa, S. Noinville, H. Quiquampoix, S. Staunton, and P. Dejardin. 2010. Adsorption of alexa-labeled Bt Toxin on mica, glass, and hydrophobized glass: study by normal scanning confocal fluorescence. Biomacromolecules 11: 1661–1666. Kovach, J. 2004. Impact of multicolored Asian lady beetles as a pest of fruit and people. Am. Entomol. 50: 159-161. Landis, D. A., S. D. Wratten, and G. M. Gurr. 2000. Habitat management to conserve natural enemies of arthropod pests in agriculture. Annu. Rev. Entomol. 45: 175–201. Li, F. F., G. Y. Ye, Q. Wu, Y. F. Peng and X. X. Chen. 2007. Arthropod abundance and diversity in Bt and Non-Bt Rice Fields. Environ. Entomol. 36: 646–654. Lockwood, J. A. 1993. Environmental issues involved in biological control of rangeland grasshoppers (Orthoptera: Acrididae) with exotic agents. Environ. Entomol. 22: 503–518. Louda, S. M., D. Kendall, J. Connor, and D. Simberloff. 1997. Ecological effects of an insect introduced for the biological control of weeds. Science 277: 1088–1090. Lovei, G. L., D. A. Andow and S. Arpaia. 2009. Transgenic insecticidal crops and natural enemies: a detailed review of laboratory studies. Environ. Entomol. 38: 293–306. Marvier, M. 2001. Can risk analysis “colorize” the black and white of transgenic crops? Plant Health Progress doi: 10.1094/PHP-2001-0831-01-RV. Metcalf, R. L., and W. H. Luckman. 1994. Introduction to insect pest management, 3rd ed. John Wiley and Sons, New York. Morrison, L. W., M. D. Korzukhin, and S. D. Porter. 2005. Predicted range expansion of the invasive fire ant, Solenopsis invicta, in the eastern United States based on VEMAP global warming scenario. Div. and Dist. 102
11: 199–204. Myers, N., R. A. Mittermeier, C. G. Mittereier, G. A. B. da Fonseca, and J. Kent. 2000. Biodiversity hotspots for conservation priorities. Nature 403: 853–858. Parella, M. P., K. M. Heinz, and L. Nunney. 1992. Biological control through augmentative releases of natural enemies: a strategy whose time has come. Am. Entomol. 38: 172–180. Parmesan, C. 2006. Ecological and evolutionary responses to recent climate change. Annu. Rev. Ecol. Syst. 17: 617–669. Pielou, E. C. 1969. An introduction to mathematical ecology. Wiley Interscience, New York. Pielou, E. C. 1975. Ecology diversity. John Wiley and Sons, New York. Pool, R. W. 1974. An introduction to quantitative ecology. McGraw-Hill, New York. Price, P. W. 1997. Insect Ecology, 3rd ed. John Wiley and Sons, New York. Robinet, C., and A. Roques. 2010. Direct impacts of recent climate warming on insect populations. Integ. Zool. 5: 132–142. Rodríguez, M. Á., and B. A. Hawkins. 2000. Diversity, function and stability in parasitoid communities. Ecol. Lett. 3: 35–40. Rohde, K. 1992. Latitudinal gradients in species diversity: the search for the primary cause. Oikos 65: 514–527. Rombouts, I., G. Beaugrand, F. Ibanez, S. Gasparini, S. Chiba, and L. Legendre. 2009. Global latitudinal variations in marine copepod diversity and environmental factors. Proc. R. Soc. Lond. B. 276: 3053–3062. Rosenheim, J. A., D. D. Limburg, and R. G. Colfer. 1999. Impact of generalist predators on a biological control agent, Chrysoperla carnea: direct observations. Ecol. Appl. 9: 409–417. Rosenzweig, C., G. Casassa, D. J. Karoly, A. Imeson, C. Liu, A. Menzel, S. Rawlins, T. L. Root, B. Seguin, and P. Tryjanowski. 2007. Assessment of observed changes and responses in natural and managed systems, pp. 79–131. In M. L. Parry, O. F. Canziani, J. P. Palutikof, P. J. van der Linden, and C. E. Hanson [Eds.]. Climate change 2007: impacts, adaptation and vulnerability. Contribution of working group II to the fourth assessment report of the intergovernmental panel on climate change. Cambridge University Press, UK. Ruiz-Jaen, M. C., and C. Potvin. 2010. Tree diversity explains variation in ecosystem function in a neotropical forest in Panama. Biotropica. 42: 638–646. Schmeller, D.S., and K. Henle. 2008. Cultivation of genetically modified organisms: resource needs for monitoring adverse effects on biodiversity. Biodivers. Conserv. 17: 3551–3558. Schuler, T. H., I. Denholm, S. J. Clark, C. N. Stewart, and G. M. Poppy. 2004. Effects of Bt plants on the development and survival of the parasitoid Cotesia plutellae (Hymenoptera: Braconidae) in susceptible and Bt-resistant larvae of the diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae). J. Insect Physiol. 50: 435–443. Sharma, H. C., and R. Ortiz. 2000. Transgenics, pest management, and the environment. Curr. Sci. 79: 421-437. Simberloff, D., and P. Stiling. 1996. Risks of species introduced for biological control. Biol. Conserv. 78: 185-192. Singh, D. 2005. Are Bt toxin engineered plants truly safe? Curr. Sci. 88:1531-1532. Snyder, G. B., D. L. Finke, and W. E. Snyder. 2008. Predator biodiversity strengthens aphid suppression across single- and multiple-species prey communities. Biol. Control 44: 52–60. Stiling, P. D. 1996. Ecology: theories and applications, 2nd ed. Prentice Hall, Upper Saddle River, NJ. Straub, C. S., D. L. Finke, and W. E. Snyder. 2008. Are the conservation of natural enemy biodiversity and biological control compatible goals? Biol. Control 45: 225–237. Thomas, C. D., A. Cameron, R. E. Green, M. Bakkenes, L. J. Beaumont, Y.C. Collingham, B. F. N. Erasmus, M. F. de Siqueria, A. Grainger, L. Hannah, L. Hughes, B. Huntley, A. S. van Jaarsveld, G. F. Midgley, L. Miles, M. A. Oretga-Huerta, A. T. Peterson, O. L. Phillips, and S. E. Williams. 2004. Extinction risk from climate change. Nature 427: 145–148. Tilman, D., P. B. Reich, and J. M. H. Knops. 2006. Biodiversity and ecosystem stability in a decade-long grassland experiment. Nature 441: 629–632. Torre-Bueno, J. R. de la. 1989. The Torre-Bueno glossary of entomology, rev. ed. Compiled by Stephen W. Nichols; including Supplement A by
American Entomologist • Summer 2012
George S. Tulloch. New York: New York Entomological Society in cooperation with the American Museum of Natural History. Travis, J. M. J. 2003. Climate change and habitat destruction: a deadly anthropogenic cocktail. Proc. R. Soc. Lond. B. 270: 467–473. Tylianakis, J. M., T. Tscharntke and A. M. Klein. 2006. Diversity, ecosystem function, and stability of parasitoid-host interactions across a tropical habitat gradient. Ecology. 87(12):3047-3057. Van Driesche, R., M. Hoddle, and T. R. Center. 2008. Control of pests and natural enemies: an introduction to biological control, pp. 69-136. Wiley-Blackwell, Hoboken, NJ. Velkov, V. V., A. B. Medvinsky, M. S. Sokolov, A. I. Marchenko. 2005. Will transgenic plants adversely affect the environment? J. Biosci. 30: 515–548. Vinson, S. B. 1988. Physiological studies of parasitoids reveal new approaches to the biological control of insect pests. Anim. Plant Sci. 1(1): 25–32. Visser, M. E. 2008. Keeping up with a warming world; assessing the rate of adaptation to climate change. Proc. R. Soc. Lond. B. 275: 649–659. Visser, M. E., and C. Both. 2005. Shifts in phenology due to global climate change: the need for a yardstick P. R. Soc. B. 272: 2561–2569. Visser, M. E., and L. J. M. Holleman. 2001. Warmer springs disrupt the synchrony of oak and winter moth phenology. Proc. R. Soc. Lond. B. 268: 289–294. Walther, G. R., E. Post, P. Convey, A. Menzel, C. Parmesan, T. J. C. Beebee, J. -M. Fromentin, O. Hoegh-Guldberg, and F. Bairlein. 2002. Ecological responses to recent climate change. Nature. 416: 389–395. Warren, M. S., J. K. Hill, J. A. Thomas, J. Asher, R. Fox, B. Huntley, D. B. Royk, M. G. Telferk, S. Jeffcoate, P. Hardingk, G. Jeffcoate, S. G. Willis, J. N. Greatorex-Daviesk, D. Mossk, and C. D. Thomas. 2001. Rapid responses of British butterflies to opposing forces of climate and habitat change. Nature 414: 65–69. Wilby, A., and M. B. Thomas. 2002. Natural enemy diversity and pest control: patterns of pest emergence with agricultural intensification. Ecol. Lett. 5: 353–360. Wilf, P. 2008. Insect-damage fossil leaves record food web response to ancient climate change and extinction. New Phytol. 178: 486–502. Wilf, P., and C. C. Labandeira. 1999. Response of plant-insect associations to Paleocene–Eocene warming. Science 384: 2153–2156. Wraight, C. L., A. R. Zangerl, M. J. Carroll, M. R. Berenbaum. 2000. Absence of toxicity of Bacillus thuringiensis pollen to black swallowtails under field conditions. Proc. Natl. Acad. Sci. 97: 7700–7703. Yao, H, C. Jiang, G. Ye, C. Hu, and Y. Peng. 2008. Toxicological assessment of pollen from different Bt rice lines on Bombyx mori (Lepidoptera: Bombyxidae). Environ. Entomol. 37: 825–837. Zangerl, A. R., D. McKenna, C. L. Wraight, M. Carroll, P. Ficarello, R. Warner, and M. R. Berenbaum. 2001. Effects of exposure to event 176 Bacillus thuringiensis corn pollen on monarch and black swallowtail caterpillars under field conditions. Proc Natl. Acad. Sci. USA 98: 11908–11912. Zhang, G. -F., F. -H. Wan, G. L. Lovei, W. -X. Liu, and J. -Y. Guo. 2009. Transmission of Bt Toxin to the predator Propylaea japonica (Coleoptera: Coccinellidae) through its aphid prey feeding on transgenic Bt Cotton. Environ. Entomol. 35: 143–150. Zhou, Z. -S., Z. -P. Chen, and Z. -F. Xu. 2010. Niches and interspecific competitive relationships of the parasitoids, Microplitis and Campolsletis chlorldeae, of the oriental leafworm moth, Spodoptera litura, in tobacco. J. Insect Sci. 10: 1–12.
DEBATE PARTICIPANTS University of Nevada
Joy Newton is a Ph.D. candidate at the University of Nevada, Reno, in the Ecology, Evolution and Conservation Biology Department researching the interaction between the ecology of ants and how it impacts forest management and Lake Tahoe within the Tahoe Basin. Former research as a Masters student at West Texas A&M University included the fire ecology of invertebrates in short-grass prairie and a base-line inventory of invertebrates with Texas Agrilife Research in southeastern Colorado. American Entomologist • Volume 58, Number 2
Louisiana State University Katherine A. Parys is a Ph.D. candidate under S. Johnson working on biological control of Salvinia minima Baker and community interactions between biological control agents and native arthropods. Jennifer R. Gordon finished her M.S. degree at LSU under the direction of J. Ottea investigating the role of esterases as a detoxification mechanism for insecticides in populations of Culex quinquefasciatus (Say) and and has begun a Ph.D. program at the University of Kentucky. Sebe Brown is an M.S. student under J. Davis working on soybean looper resistance to methoxyfenozide. Blake Wilson completed his M.S. degree with T. E. Reagan working on pest management in sugarcane.
University of Georgia
Shakunthala Nair is a Ph.D. candidate working with Kris Braman at UGA, studying the susceptibility and mechanisms of resistance of ericaceous ornamental plants to the Andromeda lace bug Stephanitis takeyai. Whitney E. Boozer is an M.S. student working with Nancy Hinkle at the University of Georgia, studying insecticide susceptibility of the darkling beetle Alphitobius diaperinus. Rachel C. Bottjen is an M.S. student working with Michael R. Strand at the University of Georgia, and she studies the roles of bracoviral protein tyrosine phosphatases from the parasitoid, Microplitis demolitor, in host pathology. Sonja Brannon (Team Leader) is a Ph.D. candidate at the University of Georgia studying IPM in schools and federal buildings in the lab of Brian Forschler. Stephanie R. Weldon is a Ph.D. student studying a tripartite symbiosis between aphids, a bacterium, and a bacteriophage in the lab of Kerry Oliver.
Purdue University
Serena Gross is a Ph.D. student in the Department of Entomology at Purdue University. Her research focuses on the species composition of necrophilous Coleoptera and Diptera in urban and rural habitats. Previous research for her M.S. thesis tested the effects of amending soil with compost containing lignocellulosic substrates and biocontrol agents known to suppress soil-borne diseases on the Colorado potato beetle and potato-colonizing aphids.
University of Florida
Maggie Paxson is a senior undergraduate student pursuing her B.S. degree in entomology and nematology. She will begin her M.S. degree in fall 2011, under the direction of Marc Branham at the University of Florida. Her thesis will examine the systematics of Coleoptera: Phengodidae and will seek to establish an evolutionary lineage for bioluminescence and bioluminescent courtship signaling. Wendy Helmey-Hartman is pursuing a Ph.D. under the guidance of Christine Miller and her research focuses on multimodal communication and sexual selection. Gaurav Goyal graduated with a Ph.D. in December 2010 from the Department of Entomology and Nematology. The title of his dissertation was “Morphology, biology and distribution of corninfesting Ulidiidae” with the guidance of Gregg S. Nuessly. Harsimran Gill completed her Ph.D. in entomology in August 2010 (major adviser, Robert McSorley). Her dissertation title was
103
“Integrated impact of organic mulching and soil solarization on soil surface arthropods and weeds.” Currently she is working as Post-Doc Associate with Kirsten Pelz- Stelinksi at the University of Florida, Citrus Research and Education Center, Lake Alfred.
Columbia University and American Museum of Natural History
Melanie Smith is an M.A. student in conservation biology at Columbia University’s Department of Ecology, Evolution, and Environmental Biology. Advised by Matthew Palmer, her thesis looks at the arthropod diversity on New York City green roofs and how it differs based on the roof’s plant community. Isabelle Vea is a Ph.D. student in comparative biology at the Richard Gilder Graduate School at (American Museum of Natural History), advised by David Grimaldi. Her research project focuses on the phylogeny of basal scale insects (Coccoidea) incorporating fossils in amber.
where he is studying diversity and phonological patterns in termites. His thesis is “Southeastern Nearctic termites: biodiversity, spatiotemporal distribution, ecosystem engineering.” Prithwiraj D. Das is a Ph.D. student in Henry Fadamiro’s program, where he is using morphological and neurophysiological techniques to study olfaction in parasitoids. His dissertation is “Mechanism of olfaction in parasitic wasps: comparative morphological and neurophysiological studies of olfaction in a specialist (Microplitis croceipes) and generalist (Cotesia marginiventris) parasitoid.” Esther N. Ngumbi was a Ph.D. student in Henry Fadamiro’s program, where she studied the behavior of parasitoid wasps in reaction to odors from their hosts. Her dissertation is “Mechanisms of olfaction in parasitic wasps: analytical and behavioral studies of response of a specialist (Microplitis croceipes) and a generalist (Cotesia marginiventris) parasitoid to host-related odor.” She graduated in spring 2011.
The Graduate Center–CUNY
Debate Organizers
Kathleen (Kit) Schnaars Uvino is a Ph.D. candidate of the Graduate Center of CUNY, Ecology Evolution, Systematics and Behavior, whose research investigates the relationship of resistance evolution and movement in the Colorado potato beetle. She is also a member of the Hudson Bay Project, conducting research in arctic ecosystems focusing on destructive foraging by lesser snow geese and the recovery potential of tundra vegetation.
Ashfaq A. Sial is currently a post-doctoral researcher at University of California, Berkeley. His dissertation work at Washington State University focused on developing sustainable IPM programs for lepidopteran pests of tree fruits using reduced risk insecticides. He characterized the complete toxicity profile of new reducedrisk insecticides chlorantraniliprole and spinetoram against obliquebanded leafroller (OBLR) and investigated the evolution of insecticide resistance in OBLR to these chemicals. Cheri M. Abraham is a Ph.D. candidate at The University of Georgia working with S. Kristine Braman to devise sustainable management strategies to control the primary pest, serpentine leaf miner and other secondary pests in greenhouse gerberas. Components of his research include biological control, host plant resistance, and pesticides with low toxicity to natural enemies.
Auburn University
104
Be sure ESA has your current email and contact information so you don’t miss out on important elections, announcements, competitions―and connecting with more than 6,000 entomologists and other researchers from around the world through the ESA membership directory. If you move, change jobs, or change contact information, be sure to update your member record online at www.entsoc.org by selecting “member resources,” then “member account management,” or email
[email protected]. Note: your membership must be current as of July 1st and ESA must have a valid email address for you to vote in ESA’s national elections. SOCIET Y OF A AL
RICA ME
S. Addison Barden is an M.S. student in David Held’s program, where he is studying management of pests in turfgrass. His thesis is “Red imported fire ant influences on white grub populations and soil foraging characteristics in managed turfgrass.” He graduated in spring 2011. Charles D. R. Stephen is an M.S. student in Xing Ping Hu’s program,
Stay Connected!
MOLOGIC NTO
Tom Bentley is a Ph.D. candidate in ecology working with. Mark Mescher. His research explores volatile mediated interactions between herbivores and plants, and between-plant signaling. Margaret Douglas is an M.S. student in entomology. Advised by John Tooker, she is investigating whether cultural and biological tactics can contribute to sustainable slug management in reduced-tillage field crops. Ian Grettenberger is a Ph.D. candidate in entomology working with John Tooker. His research is exploring the potential of plant genotypic diversity for sustainable pest suppression and is currently focusing on soybeans and the soybean aphid. Elina Niño is a Ph.D. candidate in entomology working under the direction of Christina Grozinger. Her research focuses on behavioral, physiological, and molecular characterization of various factors (e.g., insemination volume and seminal proteins) affecting honey bee queen post-mating changes. Sheena Sidhu is a Ph.D. candidate in entomology working with Shelby Fleischer. Her research interests include promoting and enhancing native pollinators in Pennsylvanian agroecosystems through landscape and resource management. Jason Smith is a Ph.D. candidate in entomology advised by Consuelo De Moraes and Mark Mescher. His research explores chemically mediated aspects of foraging and antiherbivore defense in parasitic vines of the genus Cuscuta.
Sharing Insect Science Globally
E
The Pennsylvania State University
American Entomologist • Summer 2012
