Lethal and Sublethal Effects of Azadirachtin and ... - Oxford Journals

ECOTOXICOLOGY

Lethal and Sublethal Effects of Azadirachtin and Cypermethrin on Habrobracon hebetor (Hymenoptera: Braconidae) ZAHRA ABEDI,1 MOOSA SABER,1,2 GHOLAMHOSSEIN GHAREKHANI,1 ALI MEHRVAR,3 4 AND SHIZUO GEORGE KAMITA

J. Econ. Entomol. 107(2): 638Ð645 (2014); DOI: http://dx.doi.org/10.1603/EC13227

ABSTRACT Habrobracon hebetor Say is an ectoparasitoid of larval stage of various lepidopteran pests. Lethal and sublethal effects of azadirachtin and cypermethrin were evaluated on adult and preimaginal stages of H. hebetor under laboratory conditions. Contact exposure bioassays with adults indicated that the lethal concentration (LC50) of two commercial azadirachtin-containing formulations, NeemGuard and BioNeem, were 43.5 and 10.2 ␮g a.i./ml, respectively. The LC50 of cypermethrin was 5.4 ␮g a.i./ml. When larval stage of H. hebetor was exposed to these insecticides with a Þeld recommended concentration of NeemGuard, BioNeem, or cypermethrin by a dip protocol, the emergence rate was reduced by 39.0, 36.6, and 97.6%, respectively. To assay the sublethal effects of these insecticides, adult wasps were exposed to an LC30 concentration of the insecticides, and then demographic parameters of the surviving wasps were determined. Fecundity, fertility, and parameters including the intrinsic rate of increase (rm) were affected negatively. The rm values following exposure to NeemGuard, BioNeem, cypermethrin, or mock treatment were 0.143, 0.149, 0.160, and 0.179, respectively, female offspring per female per day, respectively. The current study showed that cypermethrin had more acute toxicity on larval and adult stages of H. hebetor compared with azadirachin. The commercial formulations of azadirachtin and cypermethrin negatively affected most of the life table parameters of the parasitoid. SemiÞeld and Þeld studies are needed for obtaining more applicable results on combining H. hebetor and the tested insecticides for an integrated pest management-based strategy for crop protection. KEY WORDS Habrobracon hebetor, neem insecticide, pyrethroid, population life table parameter

The effective integration of conventional chemical and biological control strategies is critical for the success of an integrated pest management (IPM) program (Pedigo 1999, Adan et al. 2011). Commonly used synthetic insecticides such as organophosphates, carbamates, and pyrethroids are broad-spectrum toxicants that cause signiÞcant off-target mortality to natural enemies, especially adult parasitoids (Hill and Foster 2000, Haseeb et al. 2005). Moreover, predators and parasitoids commonly are more sensitive to toxicants than their prey (Croft 1990). Thus, should chemical insecticides be incorporated into an IPM program, they should be used only when necessary and when it is least disruptive to the biological control approach (Wang et al. 2008). However, biological control offers environmentally friendly and sustainable solutions to a variety of insect pest problems. Effective plant protection that relies solely on biological control, however, is hard to achieve without the 1 Department of Plant Protection, College of Agriculture, University of Maragheh, Maragheh, Iran. 2 Corresponding author, e-mail: [email protected]. 3 Department of Plant Protection, Azarbaijan University of Shahid Madani, East-Azarbaijan, Tabriz, Iran. 4 Department of Entomology, College of Agricultural and Environmental Sciences, University of California, Davis, CA 95616.

help of conventional chemical insecticides (Kanzaki and Tanaka 2010). Mortality is the most commonly measured parameter that is used to determine the effect of an insecticide against natural enemies. Studies that only evaluate the lethal effects of insecticides, however, will underestimate their negative effects on natural enemies and other beneÞcial insects. Thus, sublethal effects should be assessed to estimate the total effect of the application of a pesticide (Galvan et al. 2005). Although sublethal effects on insect life history parameters are in general poorly studied, these parameters have important implications for the success of an IPM program, especially when a parasitoid is incorporated into an IPM program (Croft 1990). Demographic toxicology is usually considered to be an important tool for accurate assessment of the total effects of an insecticidal compound (Stark and Banks 2003). Sublethal effects of an insecticide may be manifested as reductions in life span, development rates, and fecundity, and changes in sex ratio and behavior (Croft 1990). Sublethal effects on fertility, fecundity, developmental rate, survival, and sex ratio can be measured by estimating the intrinsic rate of increase (rm) (Desneux et al. 2006).

0022-0493/14/0638Ð0645$04.00/0 䉷 2014 Entomological Society of America

April 2014

ABEDI ET AL.: EFFECTS OF AZADIRACHTIN AND CYPERMETHRIN ON H. hebetor

The release of braconid parasitoids is an effective and environmentally friendly biological control strategy for lepidopteran insect pests (Urbaneja et al. 2009). Habrobracon hebetor Say is a gregarious ectoparasitoid wasp that attacks lepidopteran larvae (Magro and Parra 2001). H. hebetor is easily mass reared, and it has been released in the Þeld as part of an effective IPM strategy for control of Helicoverpa spp. (Heimpel et al. 1997). This study evaluated the effects of biorational neem and conventional pyrethroid insecticides on H. hebetor larvae and adults. The primary active ingredient in neem insecticides is azadirachtin, a tetranortriterpenoid plant limonoid that can be extracted from the seeds of the neem tree (Azadirachta indica A.Jussieu; Spollen and Isman 1996). The precise mode of action is unknown; however, azadirachtin affects insect hormones, interfering with molting in immature insects and inhibiting reproduction in adult insects. Azadirachtin also has repellant properties, deterring insects from feeding and adult insects from laying eggs on treated plants, and is generally believed to disrupt the endocrine system of the treated insects (Schmutterer 1990). However, pyrethroids are a class of synthetic insecticides that worldwide account for ⬎30% of the global insecticide use (Usmani and Knowles 2001). Cypermethrin is widely used to control agricultural pests belonging to the orders Lepidoptera, Coleoptera, Diptera, and Hemiptera (Liu et al. 1998, Suh et al. 2000). Cypermethrin is a synthetic pyrethroid and a permethrin analog, which act primarily on the basal ganglia of the central nervous system, causing repetitive nerve action through prolongation of sodium permeability during the recovery phase of the action potential of neurons (Talebi-Jahromi 2007). In this study, in particular, we assessed the lethal and sublethal effects of the pyrethroid cypermethrin and two biorational neem insecticides against the ectoparasitoid H. hebetor. Materials and Methods Insect Culture. Adults of H. hebetor were obtained from an insectarium maintained by the Plant Protection Bureau of Mazandaran Province, Iran, in 2011. The wasps were reared on Þfth-instar larvae of Ephestia kuehniella Zeller at 26 ⫾ 1⬚C, 70 ⫾ 5% relative humidity, and a photoperiod of 16:8 (L:D) h. Adult parasitoids were allowed to feed on honey that was placed on a strip of paper. Insecticides. Two commercial formulations of azadirachtin, NeemGuard 1%EC (Shalimar International LLC Co., Dubai, United Arab Emirates) and BioNeem 0.09%EC (Safer Co., Bloomington, MN), and a commercial formulation of cypermethrin, Patron 40% EC (Ariashimi Co., Tehran, Iran) were used in these experiments. Adult Bioassays. Adult bioassays were performed with young (⬍24 h posteclosion) females by contact exposure. The exposure cage consisted of a box frame and a ßoor and ceiling made of removable glass plates (13 by 13 by 2 cm; Saber et al. 2004). Six ventilation holes covered with netting were made in three of the

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walls to prevent the accumulation of insecticide fumes. Preliminary concentration-setting bioassay experiments were carried out to determine the appropriate concentration ranges needed for the bioassays. A stock solution of each formulated insecticide was prepared at a concentration that reßected twice the Þeld recommended concentration (FRC). FRC values of NeemGuard, BioNeem, and cypermethrin were 100, 22.5, and 200 ␮g a.i./ml, respectively. Subsequently, aliquots were taken from each stock solution and mixed with water to prepare six concentrations each of NeemGuard (120, 80.5, 55.1, 37.8, 25.9, and 18 ␮g a.i./ml), BioNeem (24.3, 16.1, 10.7, 7.0, 4.7, and 3.2 ␮g a.i./ml), and cypermethrin (10, 8.1, 6.7, 5.4, 4.4, and 2.8 ␮g a.i./ml) that were used to establish concentrationÐresponse curves. Tween 80 (Merck, Darmstadt, Germany) was added to all of the insecticide dilutions at a concentration of 200 ppm as a surfactant (Rosenheim and Hoy 1988). The glass surfaces (i.e., the ßoor and ceiling) of the exposure cage were sprayed with 3 ml of each concentration of insecticide using a Potter spray tower (Burkard Mfg. Co., Rickmansworth, United Kingdom). This resulted in homogenous spray coverage deposit of 4.47 ⫾ 1.6 ␮l/cm2 (mean ⫾ SE). Control glass plates were sprayed with water plus 200 ppm of Tween 80. The plates were allowed to dry completely by placing them on the laboratory bench at room temperature for 1 h. After the glass plates were completely dry, they were assembled back into the exposure cage and 15 young (⬍24 h old) female adults were placed in each cage. The wasps were anesthetized with CO2 before placing them in the cage. All anesthetized wasps were checked to conÞrm that they regained activity. They were supplied with honey placed on a small strip of paper as food. The exposure cage was placed in a growth chamber that was set to the above described conditions. The number of dead and live wasps in each cage was scored at 24 h after the wasps were placed in the cage for cypermethrin, and at 24 and 72 h for the two formulations of azadirachtin. Parasitoids that appeared to be extremely lethargic or unable to remain upright were recorded as dead. Extremely lethargic insects in both treatments mostly died when checked for possible recovery after 24 h. Each concentration was replicated three times, and 15 adult females were used in each insecticide concentration. The bioassay trials were repeated three times. The results of each trial were tested for curve Þt using PROC GENMOD procedures (SAS Institute 2002, Robertson et al. 2007). Lethal concentration (LC30, LC50, and LC90) values with associated 95% Þducial limits were determined using PROC PROBIT software (SAS Institute 2002). The selectivity ratio of each insecticide was determined by the Hazard Quotient (HQ) approach (Campbell et al. 2000). The HQ value was calculated for adults by dividing the estimated exposure value (maximum application rate [g a.i/ha]) by the toxicity value (LR50 ⫽ median lethal rate [g a.i/ha]). Toxicity value was calculated in g a.i/ha based on spray coverage deposit rate of 4.47 ␮l/cm2 (see Adult Bioassay section).

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Table 1.

Vol. 107, no. 2

Acute insecticide toxicity on the adult stage of the ectoparasitoid H. hebetor

Insecticide

na

␹2

Slope ⫾ SE

HQb

Cypermethrin Azadirachtin (Neem Guard) Azadirachtin (BioNeem)

315 315 315

43.3 44.9 42.3

3.6 ⫾ 0.6 2.2 ⫾ 0.3 2.0 ⫾ 0.3

37 2.3 2.2

Lethal concentrations (␮g a.i./ml) LC30 (95% FL)

LC50 (95% FL)

LC90 (95% FL)

3.9 (3.1Ð4.5) 25.1 (18Ð31.1) 5.5 (4.0Ð6.9)

5.4 (4.8Ð6.1) 43.5 (35.9Ð52.2) 10.2 (8.3Ð12.6)

12.3 (10.1Ð17.1) 167.6 (121Ð296) 45.1 (30.1Ð92.2)

Lethal concentrations and 95% Þducial limits (FL) were estimated using logistic regression (SAS Institute 2002). The total number of adult wasps used for bioassay. HQ was calculated by dividing the estimated exposure value. (max application rate [g a.i./ha] by the toxicity value (LR ⫽ median lethal rate [g a.i./ha]). a

b

Immature Stage Bioassay. To assess the effect of azadirachtin and cypermethrin on immature H. hebetor, the third-instar larvae of the parasitoid were exposed by dipping them into a FRC solution of NeemGuard, BioNeem, or cypermethrin for 10 s. The parasitoids were placed on the paper towel to dry and then they transferred to a growth chamber that was set to the standard conditions indicated above. Control insects were dipped in distilled water. Three replicates (each replicate consisted of a cohort of 15 randomly chosen larvae) were exposed to each insecticide. In the Þnal assessment, the total number of emerged wasps was recorded. The data were subjected to analysis of variance (ANOVA; SAS Institute 2002) and the means were compared using Fisher protected least signiÞcant differences (LSD; P ⫽ 0.05). The insecticides were classiÞed into one of four International Organization for Biological Control (IOBC) toxicity classes (Hassan 1994) on the basis of a reduction in the studied parameters in comparison with the control. The IOBC toxicity classes are: 1) harmless, 2) slightly harmful, 3) moderately harmful, and 4) harmful. Life Table Parameters Study. To determine the life table parameters of H. hebetor after sublethal insecticide exposure, newly mated young (⬍24 h posteclosion) adult females were exposed to an LC30 concentration of NeemGuard (25.1 ␮g a.i./ml), BioNeem (5.5 ␮g a.i./ml), or cypermethrin (3.9 ␮g a.i./ml) using the exposure cage system described above. Control insects were exposed to glass plates that were sprayed with distilled water. After a 72-h-long exposure to azadirachtin or 24-h-long exposure to cypermethrin, 25 randomly selected live females were transferred individually to plastic petri dishes (60 mm in diameter) and paired with a young male (⬍24 h posteclosion). These exposure time periods were used because a pilot experiment showed that the death of azadirachtin-exposed insects occurred 48 h later than for cypermethrin-treated insects. The wasps were provided with honey as food and reared as described above. Each day, seven Þfth-instar E. kuehniella were provided to each female as hosts for oviposition. Seven host larvae were used because the upper limit of host parasitization per wasp is seven larvae per day (RaÞeeDastjerdi et al. 2008). The parasitized larvae were kept under the standard rearing conditions described above. The survival and fecundity of each of the 25 female wasps were recorded daily. The total numbers

of eggs, the number of larvae emerging from these eggs, and sex of the emerged wasp at adulthood were recorded. Daily schedules of mortality and fecundity were integrated into a life table format (Carey 1993) and used to calculate net reproductive rate (R0), mean generation time (T), rm, and Þnite rate of increase (␭) values. Jackknife pseudovalues that were computed for rm, T, doubling time (DT), R0, gross reproductive rate (GRR), and ␭ for each treatment were analyzed by ANOVA (Meyer et al. 1986, Maia et al. 2000). In addition, egg hatch rate, offspring sex ratio, adult survival, longevity, and fecundity data were collected and analyzed by ANOVA, and the means were compared as described above. A square-root transformation was performed on parameters in cases that were not normally distributed. Results Adult Bioassay. LC50 values for NeemGuard, BioNeem, and cypermethrin that were generated by the adult bioassays are shown in Table 1. The adult bioassays indicated that the acute toxicity of cypermethrin toward female adult H. hebetor was higher than that of the azadirachtin formulations because 95% Þducial limits did not overlap. The HQ values for NeemGuard and BioNeem were ⬎10-fold lower than that of cypermethrin (Table 1). The cumulative percentage mortality of H. hebetor after exposure to different concentrations of the two formulations of azadirachtin and cypermethrin are shown in Fig. 1. The highest percentage mortality was observed at 120, 24.3, and 10 ␮g a.i./ml concentrations of NeemGuard, BioNeem, and cypermethrin, respectively (Fig. 1). Immature Stage Bioassay. The effects of exposure to a Þeld-recommended concentration of NeemGuard, BioNeem, or cypermethrin at a larval stage of H. hebetor on the emergence rate are shown in Table 2. A signiÞcant reduction in parasitoid emergence was found in all of the insecticide-exposed larvae in comparison with control larvae (F ⫽ 273.5; df ⫽ 3, 176; P ⬍ 0.0001). In comparison with control larvae, the emergence rate was reduced by 97.6, 39.0, and 36.6% after exposure at the larval stage to cypermethrin, NeemGuard, and BioNeem, respectively. Life Table Parameters. Sublethal effects after exposure to an LC30 concentration of NeemGuard, BioNeem, or cypermethrin on the fecundity and lon-

April 2014


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gevity of female H. hebetor are shown in Table 3. The hatch rate and sex ratio of the offspring are also given in Table 3. In comparison with control insects, insecticide exposure during the adult stage signiÞcantly reduced the numbers of eggs laid by H. hebetor females (F ⫽ 14.7; df ⫽ 3, 96; P ⬍ 0.0001). Fecundity was reduced by 35.1, 35.0, and 18.8% after adult exposure to low-lethal concentrations of cypermethrin, NeemGuard, and BioNeem, respectively. The number of progeny produced per individual female on a daily basis (Mx) is shown in Fig. 2. There was a signiÞcant difference in fecundity between control and insecticide-treated insects (F ⫽ 8.5; df ⫽ 3, 96; P ⬍ 0.0001). Exposure to an LC30 concentration of cypermethrin, but not the azadirachtin insecticides, signiÞcantly reduced mean longevity in comparison with control insects (F ⫽ 9.8; df ⫽ 3, 96; P ⬍ 0.0001). The sex ratio of the offspring of H. hebetor that were exposed to an LC30 value of each insecticide was not affected (F ⫽ 0.47; df ⫽ 3, 96; P ⫽ 0.71). The effects of exposure to an LC30 concentration of NeemGuard, BioNeem, or cypermethrin on the population parameters of H. hebetor are shown in Table 4. In comparison with control insects, the GRR (F ⫽ 17.9; df ⫽ 3, 96; P ⬍ 0.0001) and the R0 (F ⫽ 13.1; df ⫽ 3, 96; P ⬍ 0.0001) showed signiÞcant differences after low-lethal exposure to NeemGuard and cypermethrin but not to BioNeem. The rm was signiÞcantly affected by insecticide treatment (F ⫽ 58.6; df ⫽ 3, 96; P ⬍ 0.0001). The higher rm in control insects (0.179 d⫺1) in comparison with insecticide-treated insects indicated harmful effects of insecticide exposure on the rm. Changes in the ␭ followed the same pattern as the changes in rm (F ⫽ 59.36; df ⫽ 3, 96; P ⬍ 0.0001). In comparison with control insects, T was signiÞcantly affected by low-lethal NeemGuard and BioNeem exposure but not by cypermethrin exposure (F ⫽ 68.1; df ⫽ 3, 96; P ⬍ 0.0001). The DT of the population showed a signiÞcant increase after low-lethal insecticide exposure (F ⫽ 48.4; df ⫽ 3.96; P ⬍ 0.0001). Survivorship curves are shown in Fig. 3. Age-speciÞc survivorship (lx) curves showed a leftward shift after sublethal exposure to NeemGuard, BioNeem, and cypermethrin (Fig. 3). Fig. 1. Cumulative percent mortality (mortality ⫾ SD) of H. hebetor after exposure to different concentrations (␮g a.i./ml) of NeemGuard (A), BioNeem (B), or cypermethrin (C).

Table 2.

Discussion An ideal insecticide for use in an IPM program is one that not only suppresses the pest insect popu-

Emergence rate of H. hebetor that were exposed as larvae with a field recommended concentration of each insecticide

Treatment

Exposure concn (␮g a.i./ml)

Mean percentage of adult parasitoid emergence (% ⫾ SE)

Mean reduction in the emergence rate (% ⫾ SE)

ClassiÞcation of the insecticide according to IOBCÐWPRS standardsa

Cypermethrin Azadirachtin (Neem Guard) azadirachtin (BioNeem) control

200 100 22.5 Ð

2.2 ⫾ 2.12c 55.6 ⫾ 2.22b 57.8 ⫾ 2.24b 91.1 ⫾ 2.22a

97.56 ⫾ 2.22 39.02 ⫾ 2.22 36.58 ⫾ 2.22 Ð

Moderately harmful Slightly harmful Slightly harmful Ð

Mean values in a column followed by different lowercase letter are signiÞcantly different on the basis of ANOVA with mean separation LSD (␣ ⬍ 0.05). a Hassan 1994.

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Table 3.

Vol. 107, no. 2

Biological parameters of adult H. hebetor that were exposed to an LC30 concentration of each insecticide

Insecticide

Egg laid (no. ⫾ SE)

Hatch rate (% ⫾ SE)

Longevity (days ⫾ SE)

Sex ratio (male per [male ⫹ female] ⫾ SE)

Cypermethrin Azadirachtin (Neem Guard) Azadirachtin (BioNeem) Control

76.6 ⫾ 4.5c 76.6 ⫾ 5.5c 95.7 ⫾ 5.4b 117.9 ⫾ 5.1a

71.3 ⫾ 1.3b 69.5 ⫾ 2.2b 71.4 ⫾ 1.7b 79.5 ⫾ 0.5a

15.3 ⫾ 0.8b 21.4 ⫾ 1.5a 23.6 ⫾ 1.5a 26.5 ⫾ 2.1a

0.44 ⫾ 0.02a 0.46 ⫾ 0.02a 0.46 ⫾ 0.01a 0.45 ⫾ 0.01a

Mean values in a column followed by different lowercase letter are signiÞcantly different on the basis of ANOVA with mean separation LSD (␣ ⬍0.05).

lation but also shows low activity against its natural enemies. Therefore, before an insecticide is incorporated into an IPM program, it is imperative to screen for its selectivity for natural enemies and other nontargeted insects (Sarfraz and Keddie 2005, Kanzaki and Tanaka 2010). HQ is one measure of the overall safety of an insecticidal compound toward a natural enemy. The HQ values for B. hebetor adults of NeemGuard, BioNeem, and cypermethrin were determined to be 2.3, 2.2, and 37, respectively. These HQ values suggest that NeemGuard, and BioNeem pose a 17-fold lower risk to adult H. hebetor in comparison with cypermethrin. A HQ of ⬎1 indicates that the FRC is dangerous for the tested parasitoid because it kills ⬎50% of the tested specimens. Therefore, FRC of both azadirachtin-based insecticides and cypermethrin are to be considered harmful to H. hebetor. HQ values suggested that cypermethrin pose high risk to the ectoparasitoid H. hebetor. The Pesticides and BeneÞcial Organisms working group of the International Organization for Biological ControlÐWest Palaearctic Regional Section (IOBCÐWPRS) has developed a three-tier testing scheme to help determine the ecotoxicology of an insecticidal compound (Hassan 1994). Under this scheme, pesticides that are harmless in laboratory tests are considered to be most likely harmless in the Þeld, and therefore require no further testing (Amano and Haseeb 2001). From a practical point of view, only insecticides that are classiÞed as harmless or slightly harmful are suitable for use in IPM (Stara et al. 2011). In this study, the emergence rate

of H. hebetor was reduced by 97.6, 39, and 36.6% after exposure to cypermethrin, NeemGuard, and BioNeem, respectively. According to the IOBC classiÞcation of insecticide toxicity, NeemGuard and BioNeem were classiÞed as “slightly harmful”, and cypermethrin as “moderately harmful” toward a preimaginal stage of H. hebetor. Similarly, Sarode and Sonalkar (1999) have previously reported that pyrethroid and organophosphorus insecticides show toxic effects toward the parasitoid Trichogramma chilonis Ishii whereas neem seed extracts are moderately safe. There are numerous other examples in the literature (e.g., Tillman 1995, Tillman and Scott 1997) demonstrating that exposure to a FRC of cypermethrin or other pyrethroid causes acute toxic effects against a wide range of brachonids including Microptilis croceipes Cresson, Cardiochiles nigriceps Viereck, and Cotesia marginiventris (Cresson). Pesticides that are used in IPM programs can cause numerous direct (Schneider et al. 2003) and indirect (Uckan et al. 2008) effects against natural enemies. These effects can be acute and lethal or more subtle and sublethal resulting in changes in biological and physiological parameters (Sak et al. 2009). Studies of the sublethal effects of pesticides on natural enemies often aim to assess the suitability of the pesticides for use in an IPM program (Saber 2011). Our study of sublethal effects showed that most of the stable population parameters were signiÞcantly affected by the insecticides. The rm was signiÞcantly affected by insecticide treatments. The rm is the most important life table parameter for

female progeny/female/day (mx)

6 5 4

azadirachtin (Neem Guard®) azadirachtin (Bioneem®) cypermethrin control

3 2 1 0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 age (day)

Fig. 2. Daily female progeny production (mx) by adult H. hebetor that were exposed to an LC30 concentration of each insecticide.

April 2014 Table 4.


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The effects of low-lethal insecticide exposure (LC30 concentration) on population parameters of adult H. hebetor

Treatment

Gross reproductive rate (GRR ⫾ SE)

Net reproductive rate (R0 ⫾ SE)

Intrinsic rate of increase (rm ⫾ SE)

Finite rate of increase (␭ ⫾ SE)

Generation time (T) (days ⫾ SE)

Doubling time (DT) (days ⫾ SE)

Cypermethrin Azadirachtin (Neem Guard) Azadirachtin (BioNeem) Control

41.6 ⫾ 3.7b 49.6 ⫾ 2.0b 59.3 ⫾ 1.5a 62.9 ⫾ 1.0a

32.4 ⫾ 2.1b 35.3 ⫾ 2.8b 45.9 ⫾ 2.9a 52.8 ⫾ 2.5a

0.16 ⫾ 0.003b 0.14 ⫾ 0.002c 0.15 ⫾ 0.002c 0.18 ⫾ 0.001a

1.17 ⫾ 0.003b 1.15 ⫾ 0.003c 1.16 ⫾ 0.002c 1.2 ⫾ 0.002a

21.8 ⫾ 0.16b 24.9 ⫾ 0.31a 25.7 ⫾ 0.24a 22.2 ⫾ 0.21b

4.3 ⫾ 0.07b 4.8 ⫾ 0.08a 4.7 ⫾ 0.06a 3.9 ⫾ 0.03c

Mean values in a column followed by different lowercase letter are signiÞcantly different on the basis of ANOVA with LSD test (␣ ⬍ 0.05).

evaluating population growth because rm includes the effects of age, survival rate (lx), and the number of female offspring (mx) in its calculation (Carey 1993). The lower rm value that was found after exposure to cypermethrin as well as NeemGuard and BioNeem when compared with the untreated control wasps indicated that exposure to any of these insecticides will have adverse effects on the parasitoid population. Cypermethrin showed lower effects on rm compared with the azadirachtin formulations. Exposing to the lower lethal concentration of cypermethrin may lead to lower effects on important population parameters (e.g., rm) compared with azadirachin. Our Þndings were consistent with previous studies that show that exposure to a sublethal concentration of cypermethrin induces various deleterious effects on the parasitoids Trichogramma exiguum Pinto & Platner (Suh et al. 2000), Apanteles galleriae Wilkinson (Ergin et al. 2007), and Pimpla turionellae L. (Sak et al. 2009). Similarly, the sublethal effects of the azadirachtin formulations were severe. Although, in this study, no adverse effects were observed on the longevity of H. hebetor regardless of whether the insects were directly exposed to the neem formulations by dipping or indirectly by contact with insecticide residue. In agreement with these Þndings, the mean longevity, survival rate, and foraging behavior of Diadegma mollipla Holmgren a parasitoid of the diamondback moth are not affected after exposure to two formulations of azadirachtin (Akol et al. 2002). Similarly, Stark et al. (1992) found that the survival, longevity, and reproduction of two braconid parasitoids of the tephritid fruit

age-specific survivorship (Lx)

1

ßies, Diachasmimorpha longicaudata Ashmead and D. tryoni Cameron, are not signiÞcantly affected after exposure to azadirachtin. In the same study, however, Stark et al. (1992) found that the parasitoid Psytallia incise Silvestri is negatively affected by azadirachtin exposure. Ruiu et al. (2008) also found that azadirachtin exposure signiÞcantly affects the mean longevity of the parasitoid Muscidifurax raptor Girault & Sanders. In another study by Vinuela et al. (2000), exposure to a sublethal dose of azadirachtin reduces the parasitization behavior of the braconid Opius concolor Szeplwas. At the other end of the spectrum, Schneider et al. (2003) found that azadirachtin is very toxic toward all the life parameters of Hyposoter didymator Thunberg. The mixed results of these studies indicate that there are intricate, species-speciÞc, developmental stage-speciÞc, dose-speciÞc, and timing of application effects that affect the biological outcome of azadiracthin exposure. Biorational insecticides generally have favorable ecotoxicological proÞles such as short environmental persistence that make them a good choice for use in IPM programs in vegetable crops (Garcia et al. 2006). The results in this study showed that all of insecticides have adverse effects on the population parameters of H. hebetor. Our laboratory study suggests that according to short-time effects of these insecticides, the use of neem insecticides may be compatible with the concurrent use of H. hebetor in an effective IPM program. We propose semiÞeld and Þeld studies to assess the Þeld efÞcacy of the combined use of neem insecticides and H. hebetor for effective crop protection. azadirachtin (Neem Guard®) azadirachtin (BioNeem®)

0.8

cypermethrin control

0.6 0.4 0.2 0 1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 age (day)

Fig. 3. Survivorship of adult H. hebetor after exposure to an LC30 concentration of each insecticide.

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JOURNAL OF ECONOMIC ENTOMOLOGY Acknowledgments

The work received Þnancial support from Postgraduate Education Bureau of the University of Maragheh, Iran, which is greatly appreciated.

References Cited Adan, A., E. Vinuela, P. Bengochea, F. Budia, D. P. Estal, P. Aguado, and P. Medina. 2011. Lethal and sublehal toxicity of Þpronil and imidacloprid on Psyttalia concolor (Hymenoptera: Braconidae). J. Econ. Entomol. 104: 1541Ð1549. Akol, A. M., S. Sithanantham, P.G.N. Njagi, A. Varela, and J. M. Mueke. 2002. Relative safety of sprays of two neem insecticides to Diadegma mollipla (Holmgren), a parasitoid of the diamondback moth: effects on adult longevity and foraging behavior. Crop Prot. 21: 853Ð 859. Amano, H., and M. Haseeb. 2001. Recently proposed methods and concepts of testing the effects of pesticides on the beneÞcial mite and insect species: study limitations and implications in IPM. Appl. Entomol. Zool. 36: 1Ð11. Campbell, P. J., K. C. Brown, E. G. Harrison, F. Bakker, K. L. Barrett, M. R. Candolfi, V. Canez, A. Dinter, G. Lewis, M. Mead-Briggs, et al. 2000. A Hazard Quotient approach for assessing the risk to non-target arthropods from plant protection products under 91/414/EEC: hazard quotient trigger value proposal and validation. J. Pest Sci. 73: 117Ð 124. Carey, J. R. 1993. Applied demography for biologists with special emphasis on insects. Oxford University Press, New York, NY. Croft, B. A. 1990. Arthroptera biological control agents and pesticides. Wiley, New York, NY. Desneux, N., R. Denoyelle, and L. Kaiser. 2006. A multi-step bioassay to assess the effect of the deltamethrin on the parasitic wasps, Aphidius ervi. Chemosphere 62: 1697Ð 1706. Ergin, E., A. Er, F. Uckan, and D. B. Rivers. 2007. Effect of cypermethrin exposed hosts on egg-adult development time, number offspring, sex ratio, longevity, and size Apanteles galleriae (Hymenoptera: Braconidae). Belg. J. Zool. 137: 27Ð31. Galvan, T. L., R. L. Koch, and W. D. Hutchison. 2005. Effects of spinosad and indoxacarb on survival, development, and reproduction of the multicolored Asian lady beetle (Coleoptera: Coccinellidae). Biol. Control 34: 108 Ð114. Garcia, J. F., E. Grisoto, J. D. Vendramim, and B.P.S. Machado. 2006. Bioactivity of neem, Azadirachta indica, against spittlebug Mahanarva fimbriolata (Hemiptera: Cercopidae) on sugarcane. J. Econ. Entomol. 99: 2010 Ð 2014. Haseeb, M., H. Amano, and T. X. Liu. 2005. Effects of selected insecticides on Diadegma semiclausum (Hymenoptera: Ichneumonidae) and Oomyzus sokolowskii (Hymenoptera: Eulophidae), parasitoids of Plutella xylostella (Lepidoptera: Plutellidae). Insect Sci. 12: 163Ð170. Hassan, S. A. 1994. Activities of the IOBC/WPRS working group pesticides and beneÞcial organisms. IOBC/WPRS Bull. 17: 1Ð5. Heimpel, G. E., M. F. Antolin, R. A. Franqu, and M. R. Strand. 1997. Reproductive isolation and genetic variation between two ÔstrainsÕ of Bracon hebetor (Hymenoptera: Braconidae). Biol. Control 9: 149 Ð156. Hill, T. A., and R. E. Foster. 2000. Effect on insecticides on the diamondback moth (Lepidoptera: Plutellidae) and its

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parasitoid Diadegma insulare (Hymenoptera: Ichneumonidae). J. Econ. Entomol. 93: 763Ð768. Kanzaki, S., and T. Tanaka. 2010. Different responses of a solitary (Meteorus pulchricornis) and a gregarious (Cotesia kariyai) endoparasitoid to four insecticides in the host Pseudaletia separata. J. Pestic. Sci. 35: 1Ð9. Liu, M. Y., D. L. Bull, and F.W.J. R. Plapp. 1998. Effects of exposure to cypermethrin on saxitoxin binding in susceptible and pyrethroid resistant houseßies. Arch. Insect Biochem. Physiol. 37: 73Ð79. Magro, S. R., and J.R.P. Parra. 2001. Biology of ectoparasitoid Bracon hebetor Say (Hymenoptera: Braconidae) on seven lepidopteran species. Sci. Agric. 58: 693Ð 698. Maia, A.H.N., J.B.L. Alferdo, and C. Campanhola. 2000. Statistical inference on associated fecundity life table parameters using jackknife technique: computational aspects. J. Econ. Entomol. 93: 511Ð518. Meyer, J. S., C. G. Igersoll, L. L. Mac Donald, and M. S. Boyce. 1986. Estimating uncertainty in population growth: jackknife vs. bootstrap techniques. Ecology 67: 1156 Ð1166. Pedigo, L. P. 1999. Entomology and pest management. Prentice Hall, Englewood Cliffs, NJ. Rafiee-Dastjerdi, H., M. J. Hejazi, G. Nouri-Ghanbalani, and M. Saber. 2008. Toxicity of some biorational and conventional insecticides to cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae) and its ectoparasitoid, Habrobracon hebetor (Hymenoptera: Braconidae). J. Entomol. Soc. Iran 28: 27Ð37. Robertson, J. L., R. M. Russell, H. K. Preisler, and N. E. Savin. 2007. Bioassay with arthropods. CRC, London, United Kingdom. Rosenheim, J. A., and M. A. Hoy. 1988. Sublethal effects of pesticides on the parasitoid Aphytis melinus (Hymenoptera: Aphelinidae). J. Econ. Entomol. 81: 476 Ð 483. Ruiu, L., A. Satta, and I. Floris. 2008. Effect of azadirachtinbased formulation on the non-target muscoid ßy parasitoid Muscidifurax raptor (Hymenoptera: Pteromalidae). Biol. Control 47: 66 Ð70. Saber, M. 2011. Acute and population level toxicity of imidacloprid and fenpyroximate on an important egg parasitoid, Trichogramma cacoeciae (Hymenoptera: Trichogrammatidae). Ecotoxicology 20: 1476 Ð1484. Saber, M., M. J. Hejazi, and S. A. Hassan. 2004. Effects of Azadirachtin/Neemazal on different stages and adult life table parameters of Trichogramma cacoeciae (Hymenoptera: Trichogrammatidae). J. Econ. Entomol. 97: 905Ð910. ¨ nu¨ l, and F. Uckan. 2009. Effects of Sak, O., E. E. Gu¨ lgO cypermethrin exposed to host on the developmental biology of Pimpla turionellae (Hymenoptera: Ichneumonidae). Ann. Entomol. Soc. Am. 102: 288 Ð294. Sarfraz, M., and B. A. Keddie. 2005. Conserving the efÞcacy of insecticides against Plutella xylostella (L.) (Lep., Plutellidae). J. Appl. Entomol. 129: 149 Ð157. Sarode, S. V., and V. U. Sonalkar. 1999. Inßuence of different insecticides on parasitization of Corcyra cephalonica by Trichogramma chilonis Ishii. Pestic. Res. J. 11: 99 Ð101. SAS Institute. 2002. The SAS system for Windows. SAS Institute, Cary, NC. Schmutterer, H. 1990. Properties and potential of natural pesticides from the neem tree, Azadirachta indica. Annu. Rev. Entomol. 35: 271Ð297. Schneider, M. A., G. Smagghe, A. Gobbi, and E. Vinuela. 2003. Toxicity and pharmacokinetics of insect growth regulators and other novel insecticides on pupae of Hyposoter didymator (Hymenoptera:Ichneumonidae), a parasitoid of early larval instars of lepidopteran pests. J. Econ. Entomol. 96: 1054 Ð1065.

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Spollen, K. M., and M. B. Isman. 1996. Acute and sublethal effects of a neem insecticide on the commercial biological control agents Phytoseilus persimilis and Amblyseius cucumeris (Acari: Phytoseiidae) and Aphidoletes aphidimyza (Diptera: Cecidomyiidae). J. Econ. Entomol. 89: 1379 Ð1386. Stara, J., J. Ourednicjova, and F. Kocourek. 2011. Laboratory evaluation of the side effects of insecticides on Aphidius colemani (Hymenoptera: Aphidiidae), Aphidoletes aphidimyza (Diptera: Cecidomyiidae), and Neoseiulus cucumeris (Acari: Phytoseidae). J. Pestic. Sci. 84: 25Ð 31. Stark, J. D., and J. E. Banks. 2003. Population-level effects of pesticides and other toxicant on arthropods. Annu. Rev. Entomol. 48: 505Ð519. Stark, J. D., T.T.Y. Wong, R. I. Vargas, and R. K. Thalman. 1992. Survival, longevity, and reproduction of tephritid fruit ßy parasitoids (Hymenoptera: Braconidae) reared from fruit ßies exposed to azadirachtin. J. Econ. Entomol. 85: 1125Ð1129. Suh, C.P.C., D. B. Orr, and J. W. Van Duyn. 2000. Effect of insecticides on Trichogramma exiguum (Hymenoptera; Trichogrammatidae) preimaginal development and adult survival. J. Econ. Entomol. 93: 577Ð583. Talebi-Jahromi, K. 2007. Pesticide toxicology, p. 492. University of Tehran Publication, Tehran, Iran. Tillman, P. G. 1995. Susceptibility of Microplitis croceipes and Cardiochiles nigriceps (Hymenoptera: Braconidae) to Þeld rates of selected cotton insecticides. J. Entomol. Sci. 30: 390 Ð396. Tillman, P. G., and W. Scott. 1997. Susceptibility of Cotesia marginiventris (Hymenoptera: Braconidae) to Þeld rates

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of selected cotton insecticides. J. Entomol. Sci. 32: 303Ð 310. Uckan, F., A. Tuven, A. Er, and E. Ergin. 2008. Effects of gibberellic acid on biological parameters of the larval endoparasitoid Apanteles galleriae (Hymenoptera: Braconidae). Ann. Entomol. Soc. Am. 101: 593Ð597. Urbaneja, A., P. Chueca, H. Monto, S. Pascual-Ruiz, O., Dembilio, P., Vanaclocha, R. Abad-Moyano, T. Pina, and P. Castan era. 2009. Chemical alternatives to Malathion for controlling Ceratitis capitata (Diptera: Tephritidae), and their side effects on natural enemies in Spanish citrus orchards. J. Econ. Entomol. 102: 144 Ð151. Usmani, K. A., and C. O. Knowles. 2001. Toxicity of pyrethroids and effect of synergists to larval and adult Helicoverpa zea, Spodoptera frugiperda, and Agrotis ipsilon (Lepidoptera: Noctuidae). J. Econ. Entomol. 94: 868 Ð 873. Vinuela, E., A. Adan, G. Smagghe, M. Gonzalez, M. P. Medina, F. Budia, H. Vogt, and P. Del Estal. 2000. Laboratory effects of ingestion of azadirachtin by two pests (Ceratitis capitata and Spodoptera exigua) and three natural enemies Chrysoperla carnea, Opius concolor and Podisus maculiventris. Biocontrol Sci. Technol. 10: 165Ð177. Wang, H. Y., Y. Yang, J. Y. Su, J. L. Shen, C. F. Gao, and Y. Ch. Zhu. 2008. Assessment of the impact of insecticides on Anagrus nilaparvatae (Pang et Wang) (Hymenoptera: Mymanidae), an egg parasitoid of the rice planthopper, Nilaparvata lugens (Hemiptera: Delphacidae). Crop Prot. 27: 514 Ð522. Received 15 May 2013; accepted 25 January 2014.