(Lepidoptera: Tortricidae) With Pear Ester Plus Acetic ... - PubAg - USDA

CHEMICAL ECOLOGY

Improved Monitoring of Female Codling Moth (Lepidoptera: Tortricidae) With Pear Ester Plus Acetic Acid in Sex Pheromone-Treated Orchards ALAN KNIGHT1 Yakima Agricultural Research Laboratory, Agricultural Research Service, United States Department of Agriculture, 5230 Konnowac Pass Road, Wapato, WA 98951

Environ. Entomol. 39(4): 1283Ð1290 (2010); DOI: 10.1603/EN10034

ABSTRACT The performance of clear delta traps baited with 3.0 mg of pear ester, ethyl (E,Z)2,4-decadienoate, and 5.0 ml of acetic acid in separate lures was compared with orange delta traps baited with a single lure containing 3.0 mg of both pear ester and the sex pheromone, (E,E)-8,10dodecadien-1-ol (codlemone) for codling moth, Cydia pomonella (L.), in apple, Malus domestica (Borkhausen). Residual analyses and Þeld tests demonstrated that both the pear ester and acetic acid lures were effective for at least 8 wk. The two trap-lure combinations caught a similar number of total moths in an orchard treated with sex pheromone dispensers during short-term trials in 2008. However, the mean catch of female moths was signiÞcantly higher and male moths signiÞcantly lower in clear traps baited with pear ester and acetic acid versus orange traps baited with pear ester and codlemone. Season-long studies were conducted with these two trap-lure combinations in orchards treated with (n ⫽ 6) and without (n ⫽ 7) sex pheromone dispensers during 2009. The two trap-lure combinations caught similar numbers of moths in dispenser-treated orchards. In contrast, total catch was signiÞcantly higher (⬎2-fold) in the orange compared with the clear traps in untreated orchards. The clear caught ⬎6-fold more females than the orange trap in both types of orchards. These studies suggest that deploying clear delta traps baited with pear ester and acetic acid can be an effective monitoring tool for female codling moth and an alternative to codlemone-baited traps in sex pheromone-treated orchards. KEY WORDS apple, Cydia pomonella, traps, mating disruption, codlemone

Implementing an effective integrated management program for codling moth, Cydia pomonella (L.), that combines the use of sex pheromones for mating disruption with judicious use of insecticide sprays in pome fruits and walnuts requires the collection of reliable, season-long data on pest densities (Witzgall et al. 2008). Prediction of the phenology and estimates of population densities of codling moth based on male moth ßight data has been a widely-used and effective correlative approach (Knight and Croft 1991). Direct monitoring of females using pear ester, ethyl (E,Z)2,4-decadienoate, however, can improve both the prediction of the timing of Þrst egg hatch and the risk of fruit injury in sex pheromone-treated orchards (Knight and Light 2005a,b). Unfortunately, Þeld evaluations of pear ester to monitor codling moth generated variable results. For example, the effectiveness of pear ester varies among crops (walnut ⬎ apple ⬎ pear) and cultivars (Granny Smith ⬎ other apple cultivars) (Light et al. 2001, Thwaite et al. 2004, Knight and Light 2005c). In addition, pear ester has not performed similarly in different fruit production areas 1

Corresponding author, e-mail: [email protected].

with regard to either the relative magnitude of moth catch compared with sex pheromone-baited traps or the proportion of moth catch that are females (Ioriatti et al. 2003, Thwaite et al. 2004, IlÕõ`chev 2004, Trimble and El-Sayed 2005, Knight and Light 2005d, Kutinokova et al. 2005, Mitchell et al. 2008). Instead of using pear ester alone, many pest managers now use a Combo lure loaded with both (E,E)-8,10-dodecadien1-ol (codlemone) and pear ester because it typically outperforms standard codlemone lures in sex pheromone-treated orchards and is long lasting (Knight et al. 2005, 2010). Yet, the proportion of female moths caught with the Combo lure is low in pome fruit orchards (⬍10%), and few managers will sex moths or consider the female moth catches in formulating management decisions (Hawkins and Hilton 2008). The effectiveness of pear ester in capturing both sexes of codling moth in traps has been improved by the addition to traps of a vial containing glacial acetic acid (Landolt et al. 2007). In this study, a signiÞcant positive interaction of acetic acid and pear ester was found in three Þeld trials, each using a different type of colored trap; however, the relative attractiveness of these two attractants was not compared with a

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ENVIRONMENTAL ENTOMOLOGY

codlemone lure. Switching from a colored to a clear delta trap signiÞcantly increased both male and female catches in traps baited with pear ester, pear ester plus acetic acid, and the Combo lure (Knight 2010). Yet, total moth catches were still signiÞcantly lower in a clear trap baited with pear ester plus acetic acid than in an orange trap baited with the Combo lure. However, these studies were not conducted in orchards treated with sex pheromone. In this work, results are reported from studies that compared moth catches in clear delta traps baited with pear ester plus acetic acid with orange delta traps baited with pear ester plus codlemone in both sex pheromone-treated and untreated orchards. In addition, the residual content and relative attractiveness of the pear ester and acetic acid lures were evaluated. Materials and Methods Experimental Design. Delta-shaped traps were used in all Þeld tests. White plastic delta traps used in 2006 Ð 07 were supplied by Tre´ ce´ (Adair, OK), and orange plastic delta traps used in 2008 Ð 09 by Suterra LLC (Bend, OR). Delta trap dimensions (length ⫻ width ⫻ height) were 28 ⫻ 20 ⫻ 12 cm. Traps had a 20 ⫻ 20-cm base and a 3.0-cm ßap at each trap opening. The area of the trapÕs opening was ⬇65.8 cm2 at each end. A white sticky liner was inserted over the base of the white and orange traps. Clear delta traps used in 2008 were made from rolls of semirigid UV-stabilized plastic Þlm (0.25 mm thickness; W. J. Dennis, Elgin, IL), and cut and folded to the same dimensions as the commercial traps. Trap liners (18.5 ⫻ 19.5 cm) were also made from the same clear plastic and coated with ⬇10.0 g of Tangle-trap adhesive (The Tanglefoot Co., Grand Rapids, MI). An orange 7.0 ⫻ 11.0-cm plastic shield was stapled to the outside top center of the clear trap to provide shading for the lure. A 15-cm piece of 1.4-cm-wide yellow tie strapping (Postal Products Unlimited, Milwaukie, WI) was laced through slits made in both the trap and shield and attached to a U-shaped neon orange plastic clip (4.0 ⫻ 5.5 cm) that is used with hand-applied CheckMate pheromone dispensers (Suterra LLC). Clear traps used in 2009 were provided by Suterra LLC and differed somewhat from the previous clear traps: smaller orange shield, 5.3 ⫻ 8.7 cm; clear liners were coated with a proprietary dry-touch hot-melt adhesive; and traps were hung with a wire hanger. All traps were attached to a 1.3-m white PVC pipe in which an L-shaped arm was placed over a branch in the canopy and hung ⬇3 m above the ground (Knight et al. 2006). Traps were randomized and evenly spaced 15Ð30 m apart in orchards. Moths were removed from traps and sexed with the aid of a microscope in the laboratory. Traps were rotated or rerandomized on each date. Traps were baited with either one or two types of lures. Gray halobutyl elastomer septa loaded with 3.0 mg of pear ester, Pherocon CM-DA (Tre´ ce´ ), or 3.0 mg of pear ester and 3.0 mg of codlemone, Pherocon CM-DA Combo (Tre´ ce´ ), was pinned to the inside roof of traps. Acetic acid lures were added to traps baited

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with pear ester and were made by drilling 3.0-mm holes in the caps of 8.0-ml polyethylene vials (NalgNunc International, Rochester, NY). Each vial was loaded with two small cotton balls and 5.0 ml of glacial acetic acid (Sigma-Aldrich, St. Louis, MO). Vials were situated upright in the center of the sticky liner. Field Aging of Pear Ester Septa. Studies were conducted to assess both the residual content of pear ester septa and their relative attractiveness as a function of aging. Septa used for residual analysis were pinned to the inside top of white delta traps. On each sampling date (weeks 0, 1Ð 4, and 7 in 2006; weeks 0, 1Ð7, 9, and 10 in 2007), four lures were randomly collected, wrapped in aluminum foil, and stored at ⫺15⬚C. Chemical compounds in individual septa were extracted with 50 ml of dichloromethane using the methods of Brown and McDonough (1986). Extracts were analyzed with a Hewlett-Packard 5890 GC equipped with a Rtx-1 column (30 m ⫻ 0.25 mm internal diameter; Restek, Bellefonte, PA). The program used an initial setting of 80⬚C, with a ramping cycle of 10⬚C increase per minute, and Þnal temperature of 250⬚C for 10 min. A standard curve for pear ester was generated with sample concentrations from 4.0 to 64.0 ␮g/ml. Methyl myristate was included as an internal standard. Recovery rates exceeded 98% in all samples. Field trials were conducted in a 2.0-ha mixed block of Red Delicious and Golden Delicious situated near Parker, WA (46⬚61⬘N, 120⬚48⬘W), to assess moth catch in white delta traps baited with either new or Þeldaged septa. Fifteen and eight replicates of each lure type (new and aged) were tested on each date in 2006 and 2007, respectively. Before the start of each experiment, one set of traps (“aged”) with new lures and without sticky liners was placed in an adjacent block of trees to generate 1-wk-old aged lures. These traps were then taken down, randomized with another set of traps baited with new lures (“new”), and placed in an array in the experimental orchard to start each trial. Trials were conducted from 28 June to 5 September 2006 and from 25 April to 20 June 2007. All liners were removed from traps, and moths were counted and sexed each week. Lures were not replaced in aged traps during each experiment, and lures were replaced in new traps each week. All traps were rerandomized within the orchard on each sampling date. Field Aging of Acetic Acid Vials. The weight loss of plastic vials loaded with acetic acid was measured over 16 wk from 29 April to 19 August 2009. Vials with two cotton balls were Þlled with 5.0 ml of glacial acetic acid and weighed. Individual vials (n ⫽ 8) were placed in clear delta traps that were hung in the canopy of two linden trees, Tilia cordata Miller, at the Yakima Agricultural Research Laboratory (Wapato, WA). Vials were reweighed weekly. Mean daily temperatures during the trial period were obtained from Washington State UniversityÕs AgWeatherNetÕs Konnowac Pass station (http://weather.wsu.edu/awn. php), which was located 50 m from the traps. The attractiveness of aged vials was evaluated in a Þeld trial in a 4.0-ha Delicious apple orchard situated 5 km north of Toppenish, WA (46⬚23⬘N, 120⬚19⬘W).

August 2010

KNIGHT: IMPROVED MONITORING WITH PEAR ESTER AND ACETIC ACID

Before the trial, 25 vials were Þlled with 5.0 ml of acetic acid and weighed on 2 June 2009. Five vials were taped shut and stored at 5⬚C. The remaining 20 vials were placed on trays in a room maintained at 25⬚C. Five vials were weighed, taped shut, and stored every 2 wk through 28 July. A Þeld trial was conducted on 12 August to compare the attractiveness of each group of laboratory-aged vials. Orange delta traps baited with a pear ester septum with and without an acetic acid vial (0, 2, 4, 6, and 8 wk old) were randomly placed in the orchard. Traps were removed 7 d later, and all moths were counted and sexed. 2008 Trial. Field studies were conducted to compare the attractiveness of clear delta traps baited with pear ester plus acetic acid versus orange traps baited with the Combo lure in a 20-yr-old 8.0-ha Delicious orchard situated 10.0 km southwest of Wapato, WA (46.24⬚N, 120.29⬚W). CheckMate CM XL1000 (Suterra LLC) hand-applied dispensers were placed at a rate of 500 dispensers ha⫺1 in a 4.0-ha area within the orchard on 26 April. Trials were conducted during four time periods: 13Ð23 June, 23 JulyÐ5 August, 9 Ð19 August, and 19- 29 August. Ten replicates of each trap-lure combination were randomly placed in the treated area on each date. New traps and lures were used in each trial, and traps were rerandomized. 2009 Trials. Thirteen apple orchards of mixed cultivars situated in the Yakima Valley near Wapato, Parker, Toppenish, Buena (46.40⬚N, 120.30⬚W), Zillah (46.24⬚N, 120.15⬚W), and Moxee (46.33⬚N, 120.23⬚W) were selected in the spring to evaluate the performance of clear delta traps baited with pear ester plus acetic acid versus orange delta traps baited with the Combo lure over the entire season. Six orchards were treated with sex pheromone dispensers (Isomate, PaciÞc Biocontrol, Vancouver, WA) applied at densities from 500 to 1,000 ha⫺1, and seven orchards were not treated with mating disruption. Seasonal use of insecticides for codling moth varied widely among orchards ranging from zero to six sprays. One of each trap-lure type was placed near the border of each orchard on 22Ð23 April 2009. Traps were checked and rotated weekly until 2 September. All lures were replaced on 17 June after 8 wk, and 6 wk later on 28 July. Liners were replaced every week. The start of second generation moth ßight was predicted to begin during weeks 9 and 10 (18 JuneÐ2 July) based on the accumulation of 455 DD (above a lower threshold of 10⬚C) from the start of sustained male catch (Knight 2007). The percentage of fruit injury by codling moth was sampled in each orchard during the week of 14 September. Thirty fruits situated in the upper half of the canopy were randomly selected and inspected from 20 trees situated between the two traps. Weekly total moth catches for each trap-lure combination in sex pheromone-treated orchards were grouped numerically from 1 to 10 and then by groups of 10 and summarized to calculate the proportion of catches within each group with ⱖ1 and ⱖ2 female moths. Statistical Analyses. A log and angular transformation were used to normalize count and proportional data before analysis, respectively (Analytical Software

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Fig. 1. Mean (SE) residual content of pear ester in Pherocon CM-DA lures aged in the Þeld during 2006 and 2007.

2003). Moth catches with new and aged pear ester lures in 2006 and 2007 were analyzed with a two-way analysis of variance (ANOVA) with lure type and week as factors in the model that included the interaction term. Linear regression analysis was used to Þt the residual content of pear ester in Þeld-aged septa to length of time. Multiple regression was used to predict the weekly weight loss of acetic acid vials as a function of mean temperature during the week and the age of the vial. The relative attractiveness of acetic acid vials was compared with a one-way ANOVA. Moth catch data from 2008 were analyzed with a factorial ANOVA using a completely randomized design with date as a replication factor. Moth catch data from 2009 were analyzed separately for sex pheromone-treated and untreated orchards with a factorial ANOVA using date as a replication factor and orchard as a blocking factor. ANOVA was used to compare the proportion of females caught in the two trap-lure combinations. A P value of 0.05 was used to establish signiÞcance in all tests. TukeyÕs method was used to detect signiÞcant pairwise comparisons within signiÞcant ANOVAs. Results Field Aging of Pear Ester Septa. The residual content of pear ester in septa (y) Þeld-aged in both 2006 and 2007 Þt a log decay curve with the numbers of days (x) lures were aged in the Þeld: ln(y) ⫽ 1.025 ⫺ 0.03x, r2 ⫽ 0.97, P ⬍ 0.0001 (Fig. 1). Total and female moth catches varied signiÞcantly over both ßight periods in 2006 and 2007 (Table 1). Mean weekly moth catches ranged from zero to nearly eight moths per trap in both trials, and females comprised ⬇40% of catch with either lure in both years. Mean total and female catches did not vary between new and aged lures in either study. The interaction of lure type and week for total and female moths was also not signiÞcant in either year. Moth catches were low after 6 wk in both trials with either lure type (Table 1). Field Aging of Acetic Acid Vials. Weekly weight loss of vials remained fairly consistent for the Þrst 13 wk in the 2009 Þeld test ranging from 290 to 550 mg (Fig. 2).

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Vol. 39, no. 4

Comparison of codling moth catches in white delta traps baited with new and ﬁeld-aged pear ester septa in 2006 and 2007 Mean (SE) moth catch, 28 JuneÐ5 Sept. 2006

Week 1 2 3 4 5 6 7 8 9 10 ANOVA Lure Date Lure ⫻ date

Total

Mean (SE) moth catch, 25 AprilÐ20 June 2007

Females

Total

Females

New

Aged

New

Aged

New

Aged

New

Aged

0.1 (0.1) 0.3 (0.2) 6.5 (1.6) 4.9 (1.2) 2.9 (0.6) 1.6 (0.5) 0.9 (0.2) 0.9 (0.2) 0.7 (0.2) 0.1 (0.1)

0.3 (0.1)D 0.6 (0.2)CD 6.4 (1.4)A 5.3 (1.4)A 2.4 (0.6)B 1.1 (0.3)C 0.9 (0.4)C 0.3 (0.2)CD 0.3 (0.2)CD 0.2 (0.1)D

0.1 (0.1) 0.3 (0.2) 4.2 (1.4) 2.5 (0.5) 1.3 (0.4) 0.7 (0.2) 0.4 (0.2) 0.3 (0.2) 0.1 (0.1) 0.1 (0.1)

0.1 (0.1)C 0.3 (0.1)C 3.9 (0.9)A 2.3 (0.5)A 1.1 (0.3)B 0.4 (0.1)BC 0.5 (0.3)BC 0.1 (0.1)C 0.1 (0.1)C 0.2 (0.1)C

4.9 (1.6) 3.4 (0.8) 5.0 (1.0) 2.5 (0.7) 3.4 (0.7) 1.3 (0.6) 0.1 (0.1) 0.0 (0.0) Ð Ð

3.8 (0.7)AB 4.4 (0.6)AB 7.6 (1.7)A 2.6 (0.6)B 4.6 (0.8)AB 0.6 (0.3)C 0.0 (0.0)C 0.1 (0.1)C Ð Ð

0.6 (0.3) 1.0 (0.4) 1.9 (0.4) 1.5 (0.5) 1.9 (0.7) 0.5 (0.3) 0.0 (0.0) 0.0 (0.0) Ð Ð

0.5 (0.4)BC 1.6 (0.3)AB 2.6 (1.2)A 1.3 (0.4)AB 2.4 (0.7)A 0.3 (0.3)BC 0.0 (0.0)C 0.0 (0.0)C Ð Ð

F1, 280 ⫽ 0.15, P ⫽ 0.69 F9, 280 ⫽ 21.16, P ⬍ 0.0001

F1, 280 ⫽ 0.37, P ⫽ 0.54 F9, 280 ⫽ 25.65, P ⬍ 0.0001

F1, 112 ⫽ 0.28, P ⫽ 0.60 F7, 112 ⫽ 29.35, P ⬍ 0.0001

F9, 280 ⫽ 0.83, P ⫽ 0.34

F9, 280 ⫽ 0.18, P ⫽ 0.99

F7, 112 ⫽ 0.60, P ⫽ 0.76

F1, 112 ⫽ 0.30, P ⫽ 0.59 F7, 112 ⫽ 10.66, P ⬍ 0.0001 F7, 112 ⫽ 0.51, P ⫽ 0.83

Column means followed by a different uppercase letter were signiÞcantly different for date, TukeyÕs test.

However, vials rapidly lost weight after week 12 and were empty by week 15. A signiÞcant multiple regression model was Þt to predict weekly weight loss of acetic acid vials (y) as a function of both the number of weeks aged, (x1) and mean daily temperature (⬚C) during the week, (x2); y ⫽ 12.59 ⫺ 41.60x1 ⫹ 32.67x2, r2 ⫽ 0.75, P ⬍ 0.0001. The mean weight loss of vials per week when aged at 25⬚C for 2Ð 8 wk varied signiÞcantly with 8-wk-old vials losing less weight than 2-wk-old vials. Weight loss of aged vials during the 1-wk Þeld trial also varied signiÞcantly with vials aged 6 and 8 wk losing significantly less weight than the 0- and 2-wk-old vials (Table 2). Orange delta traps baited with new pear ester lures and with acetic acid vials aged from 0 to 8 wk caught similar numbers of male, female, and total moths (Table 2). 2008 Trial. No signiÞcant difference was found in total moth catch between the clear traps baited with pear ester plus acetic acid and the orange traps baited with the Combo lure across the four 10- to 12-d trial periods (Table 3). However, the orange trap caught signiÞcantly more males and the clear trap caught signiÞcantly more females. The mean number and

Fig. 2. Mean (SE) weight loss of plastic vials with a 3.0-mm hole loaded with glacial acetic acid and the mean daily temperature over a 16-wk trial in 2009.

proportion of females were 8- and 14-fold higher in the clear than the orange trap, respectively. 2009 Trials. The relative performance of the two trap-lure combinations varied between sex pheromone-treated and untreated orchards. Total moth catch did not differ between the clear trap baited with pear ester plus acetic acid and the orange trap baited with the Combo lure in sex pheromone-treated orchards. In contrast, total moth catch was more than 2-fold higher in the orange than the clear trap in untreated orchards (Table 4). Both male and female moth catch differed signiÞcantly between the two trap-lure combinations in both orchard types. The clear trap caught 6-fold more females than the orange trap in both types of orchards. The proportions of females were ⬎0.40 and ⬍0.10 in the clear and orange trap in both types of orchards, respectively (Table 4). Moth catches in both lure-trap types showed two moth ßights of codling moth during 2009. The phenology of total and female moth catches was similar in sex pheromone-treated (Fig. 3) and untreated orchards (Fig. 4) with peaks in catches occurring during weeks 5Ð7 and 12Ð15. Consistent moth catches began the third week of the study in both orchard types (Figs. 3a and 4a). Total moth catches in sex pheromone-treated orchards during weeks 3 and 4 were signiÞcantly lower in the clear than in the orange traps, F1, 11 ⫽ 10.04, P ⬍ 0.01. Cumulative total moth catch was also somewhat lower in the clear than orange trap in sex pheromone-treated orchards during the beginning of the second moth ßight, weeks 9 Ð12, F1, 22 ⫽ 4.51, P ⬍ 0.05. The Þrst female codling moths were caught during week 3, and counts increased rapidly over the next 2 wk in both orchard types (Figs. 3b and 4b). Clear traps continued to catch female moths during every week of the season, but low female catches were recorded during weeks 9 Ð12. Orange traps baited with the Combo lure failed to catch any female moths in sex pheromone-treated orchards during weeks 1Ð3, 10 Ð12, 17, and 19; and similarly in untreated orchards during weeks 1Ð2, 7, 9, 12, and

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Table 2. Comparison of the weight loss of acetic acid from aged vials and the attractiveness of orange delta traps baited with gray septa loaded with pear ester with aged acetic acid vials for codling moth, n ⴝ 5, 2009 Vial age (wk)a 0 2 4 6 8 ANOVA

Mean (SE) weight loss (mg/wk)

Mean (SE) moth catch

Prior to test

During test

Males

Females

Total

Ñ 588.0 (24.4)a 565.9 (17.6)ab 537.9 (9.5)ab 505.0 (2.9)b F3, 16 ⫽ 5.13 P ⬍ 0.05

364.2 (39.1)a 369.1 (27.0)a 281.7 (15.0)ab 235.6 (6.3)b 244.9 (16.8)b F4, 20 ⫽ 7.33 P ⬍ 0.001

7.2 (1.7) 7.8 (1.4) 5.2 (2.6) 5.8 (1.5) 7.4 (1.3) F4, 20 ⫽ 0.84 P ⫽ 0.52

5.0 (0.6) 7.0 (2.0 8.8 (1.2) 7.6 (1.2) 11.8 (2.3) F4, 20 ⫽ 2.38 P ⫽ 0.09

12.2 (2.1) 14.8 (3.0) 14.0 (3.0) 13.4 (2.4) 19.2 (3.2) F4, 20 ⫽ 0.81 P ⫽ 0.54

Column means followed by a different lowercase letter were signiÞcantly different, P ⬍ 0.05, TukeyÕs test. All traps were baited with the Pherocon CM-DA gray septum and acetic acid vials aged from 0 to 8 wk at 25⬚C.

a

17Ð19. Levels of fruit injury from codling moth in mid-September were ⬎1.0% in all but two orchards. The mean (SE) percentages of fruit injury were 12.9 (5.2) and 20.1 (13.0) in the sex pheromone-treated and untreated orchards, respectively. The proportions of clear delta traps baited with pear ester plus acetic acid catching at least one or two female moths were high throughout the season (Fig. 5). All traps catching ⱖ6 moths caught at least one female. The proportion of traps catching at least two female moths reached a plateau of nearly 0.9 in traps with ⱖ6 moths. In contrast, the proportion of orange traps baited with the Combo lure catching 4 Ð 6 moths with one female was ⬍0.40 and increased to only 0.50 with moth catches from 30 to 50 moths per week and only 0.30 with two females. Discussion Accurate knowledge of the population dynamics of female codling moth within orchards would be a useful and direct approach to predict the seasonal periods of oviposition and the potential risk of fruit injury (Light et al. 2001). Early methods that were available to monitor female codling moth, such as bait and light traps, had serious limitations associated with their use, such as high cost, nonselectivity, and the difÞculty of servicing (Geier 1960). Not surprisingly, the development of inexpensive and effective codlemone-baited traps, although they only caught male moths, largely replaced these methods (Vickers and Rothschild 1991). A clear oil-coated vertical trap is a more recent design that has proven to be an effective tool to monitor female codling moth (Knight 2000). Yet, these traps require frequent replacement and are cumbersome to service. A clear delta trap that caught numbers of female moths that were similar in magnitude to

numbers caught on the vertical pane traps was an important discovery that allows populations to be more easily monitored (Knight 2010). Data reported in this work show that clear delta traps baited with pear ester and acetic acid lures may allow female moth-based management programs for codling moth to be more fully implemented in sex pheromonetreated orchards. However, further studies are needed to deÞne the optimal emission rates of both acetic acid and pear ester to construct an effective long-lasting combined lure. Effective monitoring of adult codling moth in sex pheromone-treated orchards is critical because of the important role of moth density in the success of this approach and the potential for undetected moth immigration into treated orchards (Carde´ and Minks 1995). The apple industry has little acceptance for fruit injury by codling moth, and this pest is typically managed at low densities. Thus, growers need sensitive traps and reliable thresholds that can minimize the occurrence of false negatives (i.e., fruit injury in the absence of moth catch). The use of pear ester alone or in combination with codlemone has been more closely correlated with local levels of fruit injury (Knight and Light 2005a, Alston and Murray 2009). In addition, the Combo lure has been widely adopted by growers because of its ability to catch more moths than standard codlemone lures (Knight et al. 2005). Action thresholds based on male, female, and total moth catches in codlemone- pear ester-, and codlemone plus pear ester-baited traps have been suggested for sex pheromone-treated orchards (Gut and Brunner 1996, Knight and Light 2005a, Alston and Murray 2009). Yet, growersÕ practices in monitoring codling moth vary widely in Washington State, i.e., white, red, and orange delta traps as well as other trap types and the use of several lures. Not unexpectedly, growers use

Table 3. Comparison of moth catches in clear delta traps baited with a pear ester lure plus an acetic acid vial vs an orange delta trap baited with a lure loaded with both pear ester and codlemone during four trials in a sex pheromone-treated orchard in 2008, N ⴝ 10 Trap

Lure

Clear delta Orange delta

Pear ester ⫹ acetic acid Pear ester ⫹ codlemone ANOVA

Mean (SE) catch per trap Males

Females

Total

Mean (SE) proportion of females per trap

5.8 (1.5) 12.7 (2.5) F1, 75 ⫽ 46.05 P ⬍ 0.0001

12.8 (3.0) 1.5 (0.5) F1, 75 ⫽ 88.62 P ⬍ 0.0001

18.6 (4.4) 14.2 (2.9) F1, 75 ⫽ 0.02 P ⫽ 0.89

0.71 (0.04) 0.05 (0.01) F1, 75 ⫽ 203.65 P ⬍ 0.0001

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Table 4. Comparison of weekly catches of codling moth in clear traps baited with pear ester plus acetic acid lures vs orange traps baited with pear ester and codlemone in sex pheromone-treated and untreated orchards, 2009 Trap Sex pheromone-treated orchards, n ⫽ 6 Clear delta Orange delta Untreated orchards, n⫽7 Clear delta Orange delta

Mean (SE) catch per trap per week Males

Females

Total

Mean (SE) proportion of females per trap


5.3 (0.9) 9.1 (1.4) F1, 112 ⫽ 11.14 P ⬍ 0.01

4.3 (0.6) 0.7 (0.2) F1, 112 ⫽ 84.91 P ⬍ 0.0001

9.6 (1.4) 9.8 (1.4) F1, 112 ⫽ 0.00 P ⫽ 0.94

0.51 (0.03) 0.09 (0.02) F1, 168 ⫽ 114.85 P ⬍ 0.0001


4.0 (0.6) 15.5 (1.5) F1, 132 ⫽ 136.24 P ⬍ 0.0001

3.2 (0.5) 0.5 (0.1) F1, 132 ⫽ 80.26 P ⬍ 0.0001

7.2 (1.0) 16.0 (1.5) F1, 132 ⫽ 76.63 P ⬍ 0.0001

0.43 (0.03) 0.02 (0.01) F1, 196 ⫽ 225.28 P ⬍ 0.0001

Lure

a broad range of action thresholds based on weekly and/or cumulative moth catches in sex pheromonebaited traps to trigger insecticide treatments. Ultimately, growerÕs adoption of the clear delta trap baited with pear ester and acetic acid will depend on establishing whether this approach is more reliable than their current monitoring program. Switching to the clear delta trap baited with pear ester plus acetic acid lures will likely affect the mon-

itoring approach used by growers to manage codling moth. Data collected from sex pheromone-treated orchards suggest that action thresholds developed for total moth catch previously adopted by growers using the Combo lure may not have to be changed. However, the clear trap baited with pear ester plus acetic acid lures is much more sensitive for female moths (6-fold), and the previous action thresholds (one to

Fig. 3. Comparison of mean (SE) weekly total (A) and female (B) codling moths caught in clear delta traps baited with pear ester plus acetic acid lures versus orange delta traps baited with a Combo lure loaded with pear ester plus codlemone in six apple orchards treated with sex pheromone dispensers from 22 April to 2 September 2009.

Fig. 4. Comparison of mean (SE) weekly total (A) and female (B) codling moth caught in clear delta traps baited with pear ester plus acetic acid lures versus orange delta traps baited with a Combo lure loaded with pear ester plus codlemone in seven conventional apple orchards from 22 April to 2 September 2009.

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conducting laboratory analyses. Tom Larsen (Suterra LLC) and Bill Lingren (Tre´ ce´ ) generously provided traps and lures. Drs. Eduardo Fuentes-Contreras (University of Talca, Talca, Chile), Doug Light (Agricultural Research Service, United States Department of Agriculture, Albany, CA), David Epstein (Michigan State University, East Lansing, MI), and Peter Witzgall (Swedish University of Agricultural Sciences, Alnarp, Sweden) provided useful reviews of an earlier version of this manuscript.

References Cited Fig. 5. The proportion of traps baited with pear ester plus acetic acid lures catching 1Ð10 moths per week that also caught ⱖ1 or ⱖ2 female codling moths.

two females) developed for the Combo lure may have to be adjusted (Knight and Light 2005a). Nevertheless, further assessment of this trap and lure combination is needed in orchards with lower pest densities (⬍1.0% fruit injury) and clean orchards that are at risk from female moth immigration from surrounding unmanaged sources. One of the major difÞculties encountered while promoting the adoption of the pear ester lure was growersÕ reluctance to sex moths. For growers using the Combo lure, this was understandable, as often traps with ⬎20 moths did not have a single female. In contrast, all clear traps in sex pheromone-treated orchards baited with pear ester plus acetic acid lures with six or more moths caught at least one female, and a high proportion caught two females (Fig. 5). Thus, moths would only have to be sexed in traps that caught ⬍6 moths to check whether the female threshold had actually been reached (Knight and Light 2005a). Adoption of clear traps baited with pear ester plus acetic acid lures may also beneÞt the prediction of codling mothÕs egg hatch and timing of insecticide sprays. The concept of using the start of male moth catch in codlemone-baited traps as a biological reference point (BioÞx) to predict the start of egg hatch has been widely adopted in tree fruit pest management (Riedl et al. 1976). However, abandonment of this approach because of concerns about the variable methods and difÞculties in deÞning BioÞx in Maryland orchards has occurred (Jones et al. 2008). Timing the start of egg hatch based on the sustained start of female moth catches in pear ester-baited traps reduced the variability inherent in initiating the model with male catches (Knight and Light 2005b). However, this approach was not widely adopted as a result of the typical low catch of female moths in most commercial orchards. The much higher female moth catches in clear traps baited with pear ester plus acetic acid lures could enhance the use of this approach. Acknowledgments I thank Chey Temple and Duane Larson, United States Department of Agriculture, Agricultural Research Service (Wapato, WA), for their help in setting up the Þeld trials and

Alston, D., and M. Murray. 2009. Codling moth monitoring in mating disrupted apple orchards: development of trap thresholds and prediction of fruit injury in Utah. Proceedings, 83rd Western Orchard Pest and Disease Management Conference, 14 Ð16 January 2009, Portland, OR, Washington State University Wenatchee, WA. Analytical Software. 2003. User manual. Statistix 8, Tallahassee, FL. Brown, D. F., and L. M. McDonough. 1986. Insect sex pheromones; formulations to increase the stability of conjugated dienes. J. Econ. Entomol. 79: 922Ð927. Carde´, R. T., and A. K. Minks. 1995. Control of codling moth pests by mating disruption: successes and constraints. Annu. Rev. Entomol. 40: 559 Ð585. Geier, R. W. 1960. Physiological age of codling moth females (Cydia pomonella [L.]) caught in bait and light traps. Nature 185: 709. Gut, L. J., and J. F. Brunner. 1996. Implementing codling moth mating disruption in Washington pome fruit orchards: Tree Fruit Research Extension Center Information Series, No. 1. Washington State University, Wenatchee, WA. Hawkins, L., and R. Hilton. 2008. Commercial trials and implementation of codling moth mating disruption puffer program. Proceedings, 82nd Western Orchard Pest and Disease Management Conference, 9 Ð11 January 2008, Portland, OR. Washington State University, Wenatchee, WA. Il’ı`chev, A. L. 2004. First Australian trials of ethyl (2E, 4Z)2,4-decadienoate for monitoring of female and male codling moth Cydia pomonella (L.) (Lepidoptera: Tortricidae) in pome fruit orchards. Gen. Appl. Entomol. 33: 15Ð20. Ioriatti, C., F. Molinari, E. Pasqualini, A. De Cristofaro, S. Schmidt, and I. Espinha. 2003. The plant volatile attractant (E,Z)-2,4-ethyl-decadienoate (DA2313) for codling moth monitoring. Bolletino di Zoologia agraria di Bachicoltura 35: 127Ð137. Jones, V., M. Doerr, and J. F. Brunner. 2008. Is BioÞx necessary for predicting codling moth emergence in Washington State apple orchards? J. Econ. Entomol. 101: 1651Ð 1657. Knight, A. L. 2000. Monitoring codling moth (Lepidoptera: Tortricidae) with passive interception traps in sex pheromone-treated apple orchards. J. Econ. Entomol. 93: 1744 Ð1751. Knight, A. L. 2007. Adjusting the phenology model of codling moth (Lepidoptera: Tortricidae) in Washington State apple orchards. Environ. Entomol. 36: 1485Ð1493. Knight, A. L. 2010. Increased catch of female codling moth (Lepidoptera: Tortricidae) in kairomone-baited clear delta traps. Environ. Entomol. 39: 583Ð590. Knight, A. L., and B. A. Croft. 1991. Modeling and prediction technology, pp. 301Ð312. In L.P.S. Van der Geest and H. H. Evenhuis (eds.), Tortricid pests. Elsevier, Amsterdam, The Netherlands.

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Knight, A. L., and D. M. Light. 2005a. Timing of egg hatch by early-season codling moth (Lepidoptera: Tortricidae) predicted by moth catch in pear ester- and codlemonebaited traps. Can. Entomol. 137: 728 Ð738. Knight, A. L., and D. M. Light. 2005b. Developing action thresholds for codling moth (Lepidoptera: Tortricidae) with pear ester- and codlemone-baited traps in apple orchards treated with sex pheromone mating disruption. Can. Entomol. 137: 739 Ð747. Knight, A. L., and D. M. Light. 2005c. Factors affecting the differential capture of male and female codling moth (Lepidoptera: Tortricidae) in traps baited with ethyl (E,Z)-2,4-decadienoate. Environ. Entomol. 34: 1161Ð1169. Knight, A. L., and D. M. Light. 2005d. Dose-response of codling moth (Lepidoptera: Tortricidae) to ethyl (E, Z)2,4-decadienoate in apple orchards treated with sex pheromone dispensers. Environ. Entomol. 34: 604 Ð 609. Knight, A. L., and D. M. Light. 2005d. Seasonal ßight patterns of codling moth (Lepidoptera: Tortricidae) monitored with pear ester and codlemone-baited traps in sex pheromone-treated apple orchards. Environ. Entomol. 34: 1028 Ð1035. Knight, A. L., R. Hilton, and D. M. Light. 2005. Monitoring codling moth (Lepidoptera: Tortricidae) in apple with blends of ethyl (E, Z)-2, 4-decadienoate and codlemone. Environ. Entomol. 34: 598 Ð 603. Knight, A. L., R. Hilton, P. VanBuskirk, and D. Light. 2006. Using pear ester to monitor codling moth in sex pheromone-treated orchards. Oregon State University Press, Corvallis, OR. Knight, A., J. Haworth, B. Lingren, and V. Hebert. 2010. Combining pear ester with codlemone improves management of codling moth. IOBC/wprs Bull. (in press). Kutinokova, H., M. Subchev, D. M. Light, and B. Lingren. 2005. Interactive effects of ethyl (2E, 4Z)-2, 4-decadienoate and sex pheromone lures to codling moth: apple orchard investigations in Bulgaria. J. Plant Prot. Res. 45: 49 Ð53.

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Landolt, P. J., D. M. Suckling, and G.J.R. Judd. 2007. Positive interaction of a feeding attractant and a host kairomone for trapping the codling moth, Cydia pomonella. J. Chem. Ecol. 33: 2236 Ð2244. Light, D. M., A. L. Knight, C. A. Henrick, D. Rajapaska, B. Lingren, J. C. Dickens, K. M. Reynolds, R. G. Buttery, G. Merrill, J. Roitman, and B. C. Campbell. 2001. A pearderived kairomone with pheromonal potency that attracts male and female codling moth, Cydia pomonella (L.). Naturwissenschaften 88: 333Ð338. Mitchell, V. J., L. A. Manning, L. Cole, D. M. Suckling, and A. M. El-Sayed. 2008. EfÞcacy of the pear ester as a monitoring tool for codling moth Cydia pomonella (Lepidoptera: Tortricidae) in New Zealand apple orchards. Pest Manag. Sci. 64: 209 Ð214. Riedl, H., B. A. Croft, and A. J. Howitt. 1976. Forecasting codling moth phenology based on pheromone trap catches and physiological time models. Can. Entomol. 108: 449 Ð 460. Thwaite, W. G., A. M. Mooney, M. A. Eslick, and H. I. Nicol. 2004. Evaluating pear-derived kairomone lures for monitoring Cydia pomonella (L.) (Lepidoptera: Tortricidae) in Granny Smith apples under mating disruption. Gen. Appl. Entomol. 33: 55Ð 60. Trimble, R. M., and A. M. El-Sayed. 2005. Potential of ethyl (2E, 4Z)-2, 4-decadienoate for monitoring activity of codling moth (Lepidoptera: Tortricidae) in eastern North American apple orchards. Can. Entomol. 137: 110 Ð116. Vickers, R. A., and G.H.L. Rothschild. 1991. Use of sex pheromone for control of codling moth, pp. 339 Ð354. In L.P.S. Van der Geest and H. H. Evenhuis (eds.), Tortricid pests. Elsevier, Amsterdam, The Netherlands. Witzgall, P., L. Stelinski, L. Gut, and D. Thomson. 2008. Codling moth management and chemical ecology. Annu. Rev. Entomol. 53: 503Ð522. Received 5 February 2010; accepted 29 March 2010.