SAMPLING
Increased Catch of Female Codling Moth (Lepidoptera: Tortricidae) in Kairomone-Baited Clear Delta Traps ALAN L. KNIGHT1 Yakima Agricultural Research Laboratory, USDAÐARS, 5230 Konnowac Pass Rd., Wapato, WA 98951
Environ. Entomol. 39(2): 583Ð590 (2010); DOI: 10.1603/EN09023
ABSTRACT The relative performance of a clear delta trap baited with individual or combination sex pheromone and kairomone lures for codling moth, Cydia pomonella L., was evaluated against three vertical clear pane and colored delta traps in Þeld trials within apple, Malus domestica (Borkhausen). The clear caught signiÞcantly more moths of each sex than an orange delta trap when baited with ethyl (E,Z)-2,4-decadienoate (pear ester) and acetic acid (PE⫹AA) and performed similarly to oil-coated pane traps. The clear caught signiÞcantly more females than the orange delta trap with pear ester alone, pear ester plus (E,E)-8,10-dodecadien-1-ol (codlemone) (PE-PH), or a combination of PE-PH and acetic acid. Male moth capture was similar in both clear and colored delta traps with all codlemone lures tested. Seasonal moth catches of female moths were higher in clear than either white (second ßight, 2008) or orange (Þrst and second ßights, 2009) traps baited with PE-PH. Total moth catch was signiÞcantly higher in clear than white traps in 2008 and did not differ between clear and orange traps in 2009. Clear traps baited with acetic acid but not with pear ester, PE-PH, or when unbaited caught signiÞcantly more nontarget moths than colored traps. These studies suggest that the use of clear traps with their higher captures of female codling moths could improve both monitoring programs and the development of lure and kill strategies. KEY WORDS apple, Cydia pomonella, lures, monitoring
Accurate and reliable monitoring of codling moth, Cydia pomonella L., is a key prerequisite to implement successful sex pheromoneÐ based mating disruption (MD) programs in pome fruit and walnuts (Witzgall et al. 2008). Traps baited with (E,E)-8,10-dodecadien1-ol (codlemone) have been widely used for ⬎30 yr to establish the start of moth ßights and action thresholds (Riedl et al. 1986, Vickers and Rothschild 1991). However, despite efforts to improve monitoring of codling moth with high-load codlemone lures (Charmillot 1990), standardized placement and maintenance of traps (Knight 2007), and use of high-density trapping protocols (Gut and Brunner 1996), the reliability of current trapping programs to predict the occurrence of fruit injury in MD orchards is inconsistent (Knight and Light 2005a). The fruit volatile, ethyl (E, Z)-2,4-decadienoate (pear ester), was identiÞed as a bisexual attractant that could improve monitoring of codling moth in MDtreated orchards (Light et al. 2001). A 3-yr study conducted in Washington State apples found that both female and total moth catches in traps baited with pear ester were more reliable than male catches in similar traps baited with codlemone in predicting fruit injury and the start of egg hatch (Knight and Light 2005a, b). However, evaluations of pear ester across several geo1
Corresponding author, e-mail:
[email protected].
graphical areas have 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 with regard to the proportion of moth catch that are females (Ioriatti et al. 2003, IlÕichev 2004, Thwaite et al. 2004, Knight and Light 2005d, Kutinokova et al. 2005, Trimble and ElSayed 2005, Mitchell et al. 2008). Pear ester lures in the western United States have not been widely adopted by pest managers to monitor MD orchards for two principal reasons: relative low moth catches compared with high-load codlemone lures and the need to sex moths. Adding acetic acid to pear ester has been shown to signiÞcantly increase the catch of both sexes compared with pear ester alone; however, this lure has not yet been compared with codlemone lures in conventional or MD orchards (Landolt et al. 2007). Instead, growers have adopted a lure loaded with both codlemone and pear ester because it outperforms standard codlemone lures in MD orchards (Knight et al. 2005). The proportion of female moths caught with this lure is low (⬍10%), and few managers sex moths or consider female moth densities in formulating management decisions (Hawkins and Hilton 2008).
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A number of trap types have been evaluated for monitoring codling moth in North America including wing, diamond, delta, cylindrical, and bucket shapes (Riedl et al. 1986, Knodel and Agnello 1990, Vincent et al. 1990, Knight et al. 2002a). Laboratory and Þeld tests showed that a delta-shaped trap was an effective design and it has become the standard used in Washington State (Doerr et al. 2004). Color is an important quality affecting the performance of codlemonebaited delta traps. Knight and Miliczky (2003) reported higher male captures were obtained with painted glossy orange or green traps than with either painted or unpainted white traps. Seasonal captures of male codling moths were nearly twice as high in orange versus white traps in Þeld trials, and ßight tunnel tests showed that male moths were more likely to ßy directly into orange versus white traps, especially when illumination levels were slightly increased (Knight and Fisher 2006). At present, white, red, and orange delta traps are used by growers in Washington State. The colored traps are used primarily to reduce captures of honey bees, Apis mellifera L. (Clare et al. 2000, Knight and Milczky 2003). Few studies have assessed the effectiveness of traps baited with kairomones in capturing female codling moth. Three designs (yellow/white bucket, white wing-shaped, and red delta-shaped traps) baited with pear ester and acetic acid appeared to perform similarly to traps baited with pear ester or acetic acid alone in separate Þeld trials (Landolt et al. 2007). Laboratory tests have used white cylindrical and yellow triangular traps to assess female codling mothÕs response to host plant volatiles within ßight tunnels, but trap designs were not compared (Reed and Landolt 2002, Landolt et al. 2007). The importance of trap color for female codling moth has been assessed in two studies. Orange and white delta traps baited with codlemone and pear ester caught similar numbers of female moths in both laboratory and Þeld trials (Knight and Fisher 2006). Clear oil-coated pane traps baited with pear ester caught signiÞcantly more females than similar traps painted seven different colors (Knight 2010). Interestingly, clear and colored pane traps caught similar numbers of male codling moth in these tests. Oil-coated, clear plastic panes have been used effectively to monitor both male and female codling moth in a variety of research studies (Weissling and Knight 1994, 1995; Knight 1997, 2000, 2006, 2007). A single 0.11-m2 vertical pane trap baited with pear ester and replaced every 3Ð 4 d caught a similar number of female moths to a light trap over an entire season (Knight 2010). Unfortunately, the overall greater level of difÞculty and higher cost of their servicing versus the standard plastic or cardboard traps have largely precluded their use in pest management. However, combining the shown effectiveness of the clear pane with the convenience of a delta trap may create a new, user-friendly design that can enhance the adoption of female-based monitoring programs for codling moth. Herein, studies are reported that evaluated the effectiveness of clear delta traps baited with codlemone,
Vol. 39, no. 2
pear ester, acetic acid, and two- and three-component blends of these attractants. Materials and Methods Description of Traps and Lures. Two types of trap designs were evaluated in a series of Þeld experiments conducted during 2008: delta traps with sticky liners and clear vertical pane traps coated with several different adhesives. Orange, red, and white plastic delta traps (28 by 20 cm) were supplied by Suterra (Bend, OR) and Tre´ ce´ (Adair, OK). Traps had a 20.0 by 20.0-cm base and a 3.0-cm ßap at each opening of the trap. The area of the opening was ⬇65.8 cm2. All commercial traps had white sticky liners that were inserted over the base of the trap. Clear delta traps in 2008 were made in our laboratory from rolls of semirigid UV-stabilized plastic Þlm (0.25 mm thickness; W. J. Dennis Co., Elgin, IL) and were cut and folded to the same size as the commercial traps. Trap inserts (18.5 by 19.5 cm) were also made from the clear plastic and coated with ⬇10.0 g Tangle-trap adhesive (The Tanglefoot Co., Grand Rapids, MI). An orange 7.0 by 11.0-cm shield constructed from orange delta traps was stapled at the center of the top ridge of the trap to provide UV protection for the lure. A 15-cm piece of 1.4-cm yellow tie strapping (Postal Products Unlimited, Milwaukee, WI) was laced through slits made in both the trap and shield and attached to a U-shaped neon orange plastic clip (4.0 by 5.5 cm). Clear delta traps tested in 2009 were provided by Suterra and had identical measurements as their orange trap. However, traps had a 5.3 by 8.7-cm orange shield, clear liners were coated with a proprietary dry-touch hotmelt adhesive, and traps were hung with a wire hanger. Pane traps (33 by 33 cm) were constructed from the same rigid clear plastic Þlm as used for the delta traps in 2008. A 0.5 by 2.0-cm slit was cut in the top center of each trap 1.5 cm from the edge, and a piece of tie-strapping was threaded through this slit and used to attach each trap to an orange plastic clip. Pane traps were coated on both sides with one of three materials: a thin oil Þlm (STP Oil Treatment; STP, Ft. Lauderdale, FL) using a standard paint roller (smooth texture), 40.0 g of Tangle-trap spread evenly with a metal trowel, or a dry-touch hot-melt adhesive (Suterra). Before placement in the Þeld, the oil-coated traps were stored in a cardboard box and the other two pane traps were individually covered with a sheet of waxed paper. All traps were placed in the upper third of the treeÕs canopy, at ⬇3-m height. Pane traps were clipped to a small branch with the use of a 2.4-m pole, whereas delta traps were Þrst attached to a 1.3-m PVC pipe in which an L-shaped arm was hung over an upper branch (Knight et al. 2006). Traps were randomized and evenly spaced 15Ð30 m apart within an array at each orchard. All traps were placed ⬎10 m from the physical edge of orchards. Traps within each orchard were rotated one position forward in the array on each sampling date with the last trap in the array rotated
April 2010
KNIGHT: INCREASED CATCH OF FEMALE CODLING MOTH
back to the Þrst position. Liners were replaced on each sampling date, and moths were sexed with the aid of a microscope in the laboratory. Several commercial lures were used in these tests. Septa lures loaded with codlemone included red rubber septa loaded with 1.0 and 10.0 mg codlemone (Suterra) and proprietary gray halobutyl elastomer septa (low-load, Pherocon CM L2 and high-load, Pherocon CM Megalure (Tre´ ce´ ). Proprietary membrane codlemone lures supplied by Suterra were also tested (Biolure 1X and Biolure 10X). Gray septa containing pear ester were included in these tests including Pherocon CM-DA lure (PE) and the CM-DA Combo lure (Tre´ ce´ ) that includes both pear ester and codlemone (PE-PH). A 4.0-cm pin was pushed through the orange shield to retain septa lures just below the inside roof of the delta traps to avoid direct exposure to sunlight. The membrane lure was attached to the inside top of the trap beneath the orange shield using the adhesive pad provided on the back surface of the lure. Acetic acid lures (AA) were made by drilling 3.0-mm holes in the cap of 8.0-ml polyethylene vials (Nalg-Nunc International, Rochester, NY) and loading each vial with two small cotton balls and 5.0 ml of glacial acetic acid (Sigma-Aldrich, St. Louis, MO). Pane traps were outÞtted with a custom lure holder constructed of two pieces of PVC pipe hot-glued together and painted green (Hunter Green Gloss #2001; Krylon, Cleveland, OH). Septa were attached to a standard paperclip and placed inside the center of a 6.3-cm T-shaped tube (2.1 cm ID). Acetic acid saturated cotton balls (5.0 ml) were placed 2.0 cm from each end of a 12.5-cm tube (1.5 cm ID). The ends of each tube were covered with a red-painted cap with a 3.0-mm hole (Banner Red Gloss #2108; Krylon). These custom lure holders were attached to the end of the horizontal arm of the pvc hanger (Knight et al. 2006). Pane traps were attached to the pole by hooking the clip into a hole drilled at the end of the arm of the pole so that the pane hung vertically beneath the custom lure holder. Field Sites. Field studies in 2008 were conducted in three apple Malus domestica (Borkhausen), orchards. Orchard 1 was a 30-yr-old mixed block of ÔDeliciousÕ and ÔGranny SmithÕ situated 5 km north of Toppenish, WA (46⬚23⬘ N, 120⬚19⬘ W). Orchard 2 was a 20-yr-old ÔDeliciousÕ orchard situated 10.0 km southwest of Wapato, WA (46.24⬚ N, 120.29⬚ W). Orchard 2 in 2008 was split into four 2.0-ha areas and two areas were treated with sex pheromone dispensers on 26 April (CheckMate CM XL1000; Suterra) at a rate of 500 dispensers/ha. Orchard 3 was a mixed block of ÔGolden DeliciousÕ and ÔGranny Smith situated 7.0 km east of Moxee, WA (46⬚33⬘ N, 120⬚20⬘ W). Field studies during 2009 were conducted in orchards 1Ð3 and four additional apple orchards. These orchards were situated 2.0 km north of Parker, WA (46.30⬚ N, 120.27⬚ W), 10.0 km southwest of Wapato, WA (46.24⬚ N, 120.29⬚ W), 2.0 km north of Buena, WA (46.28⬚ N, 120.19⬚ W), and 6.0 km north of Zillah, WA (46.24⬚ N, 120.15⬚ W). Orchards varied in size from 0.3 to 16 ha. The mean canopy height of all orchards ranged from 3.5 to 4.2 m.
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GrowersÕ management practices varied widely among orchard sites, but few sprays were applied for codling moth. Levels of fruit injury before harvest were ⬎50.0% in all sites. Comparison of Traps Baited With Pear Ester. The effectiveness of clear pane traps coated with three different adhesives was compared in orchard 1 with both clear and orange delta traps using two lures: PE⫹AA and PE-PH. Each lure was evaluated in separate plots that were separated by 50 m. Five replicates of each trap type were randomized within each plot. The experiment was run from 14 to 19 May. Comparison of Different Lures in Clear and Colored Delta Traps. The relative effectiveness of the clear versus an orange delta trap when baited with four types of lures was evaluated in orchard 1. Four replicates of each trap baited with PE, PE-PH, PE⫹AA, and PE-PH⫹AA were randomized and placed in the Þeld on 20 May. Traps were checked and rotated twice, and the experiment was terminated on 3 June. Six sets of experiments were conducted to compare the effectiveness of the clear versus colored delta traps when baited with different PH lures. Studies were conducted with three high-load lures in the MD portion of orchard 2 and three standard codlemone lures were evaluated in orchards 1 and 2. The 1X red rubber placed in clear and orange delta traps was evaluated from 25 to 27 June. The 10X red rubber septa was evaluated in clear and white delta traps from 3 to 7 July. The Biolure 1X lure was evaluated in orange and clear traps from 23 to 27 June. The Biolure 10X lure was evaluated in red and clear delta traps from 18 July to 1 August. The low-load gray septum was evaluated in clear and orange delta traps from 3 to 19 June. The high-load gray septum was evaluated in red and clear delta traps from 1 to 8 July. Seasonal Comparisons of the Clear Delta Trap. Moth catch in white and clear delta traps baited with PE-PH lures was evaluated in 2008 over an 8-wk period from 7 July to 1 September in orchard 1. Seven replicates of each trap type were randomly placed on 7 July and checked every 7 d. Moth catch in orange and clear delta traps baited with PE-PH lures were compared in seven commercial orchards over 17 wk during 2009. Traps were randomly placed in one of two locations separated by 30 m in each orchard on 5 May. Traps were checked and rotated each week until 2 September. Lures were replaced after 6 wk on 17 June and again on 28 July. Evaluation of Trap Selectivity. The attractiveness of the clear, orange, white, and red delta traps for various nontargets was evaluated in orchard 3 in a series of tests using different lures in 2008. Ten replicates of each trap were randomized and placed along the western edge of the orchard on 11 August 2008. Traps were left unbaited in the Þrst test and checked on 18 August. All traps were baited with PE, rotated one position, and checked on 27 August. A separate PH lure (Pherocon L2) was added to each trap, and traps were rotated and checked again on 16 September. All septa lures were removed from traps, an AA lure was placed in the center of the sticky liner, and traps were rotated and
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Vol. 39, no. 2
Table 1. Comparisons of male, female, and total moth catches of codling moth in delta and vertical pane traps baited with pear ester and either acetic acid or sex pheromone Mean (SE) moth catch per d Pear ester ⫹ acetic acida
Trap type Orange delta Clear delta Oil-coated clear pane Tangle-trap clear pane Dry adhesive clear pane One-way ANOVA
Pear ester ⫹ codlemoneb
Male
Female
Total
Male
Female
Total
1.6 (0.4)b 8.9 (1.6)a 9.9 (1.2)a 1.7 (0.3)b 1.4 (0.4)b F4, 19 ⫽ 27.81 P ⬍ 0.0001
2.1 (0.4)b 8.5 (1.5)a 13.2 (1.4)a 1.0 (0.2)b 2.0 (0.7)b F4, 19 ⫽ 35.92 P ⬍ 0.0001
3.6 (0.7)b 17.4 (2.9)a 23.1 (2.3)a 2.7 (0.4)b 3.4 (1.0)b F4, 19 ⫽ 33.71 P ⬍ 0.0001
12.5 (0.9)ab 15.2 (1.8)a 22.6 (5.4)a 6.4 (1.4)b 5.5 (0.9)b F4, 20 ⫽ 7.93 P ⬍ 0.001
0.6 (0.2)b 2.2 (0.4)ab 5.9 (1.0)a 0.8 (90.3)b 1.2 (0.2)b F4, 20 ⫽ 8.13 P ⬍ 0.001
13.1 (0.8)ab 17.4 (1.5)a 28.5 (6.3)a 7.2 (1.6)b 6.7 (1.1)b F4, 20 ⫽ 9.30 P ⬍ 0.001
Means within the same column followed by a different letter are signiÞcantly different at P ⬍ 0.05, TukeyÕs mean comparison test. a Traps were baited with a Pherocon CM-DA lure and a polyethylene vial loaded with 5.0 ml glacial acetic acid. b Traps were baited with a Pherocon CM-DA Combo lure.
rechecked on 2 October. All insects caught on sticky liners were counted on each date, and data were summarized as lepidopterans other than codling moth, including noctuids, pyralids, and tortricids; dipterans, including primarily muscoids; and hymenopterans, including both A. mellifera and vespids. The incidental capture of coccinellids, tipulids, and pentatomids occurred among trap types but was not summarized. Statistical Analyses. All trap catch data for codling moth were summarized as the number of individuals caught per trap per day, except for the two seasonal studies where data were collected weekly. A few traps in some experiments were dislodged from trees by high winds, and these data were not included in the analyses. Count data from each experiment was evaluated for their Þt of a normal distribution (ShapiroWilks normality test; Analytical Software 2003). A log transformation was used to normalize the data. If the assumption of normality was met by either the original data or transformed data, parametric tests were used to compare treatments (analysis of variance [ANOVA] and two-sample t-tests). If the transformation did not improve the normality of the data, nonparametric tests were run with the untransformed data using the Kruskal-Wallis ANOVA of mean ranks (Analytical Software 2003). 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 Comparison of Traps Baited With Pear Ester. SigniÞcant differences in the capture of male, female, and total moths were found among several delta and pane traps baited with either PE⫹AA or PE-PH (Table 1). The oil-coated pane trap caught signiÞcantly more moths than either of the adhesive-coated panes with either lure. The clear delta with the PE⫹AA lure caught signiÞcantly more males, females, and total moths than the orange delta. Trap catches were similar between delta traps when they were baited with PEPH. The oil-coated pane trap caught similar numbers of moths to the clear delta with both lures. The orange delta with the PE⫹AA lure caught signiÞcantly fewer
moths (both sexes) and signiÞcantly fewer females with the PE-PH lure than the oil-coated pane trap. Comparison of Different Lures in Clear and Colored Delta Traps. SigniÞcant trap and lure differences were found for moth catches with four lures in clear versus orange delta traps (Table 2). Trap ⫻ lure interactions were not signiÞcant in these models. Both male and total moth catches varied signiÞcantly among all lures across both trap types. Traps baited with lures containing codlemone caught signiÞcantly more males than traps with PE or PE⫹AA lures. Similarly, traps baited with PE-PH caught signiÞcantly more total moths than traps baited with PE or PE⫹AA. Traps baited with PE-PH⫹AA, however, caught an intermediate number of males, greater than traps with a PE lure, but not different from traps baited with the other two lures. No difference was found for the mean catch of females among the four lures when analyzed across trap type. However, female catch was signiÞcantly greater in clear versus orange traps across all lures (greater than Þve-fold higher; Table 2). No signiÞcant differences were found for male catch in clear versus colored delta traps in tests with six codlemone lures (Table 3). Results were similar in both untreated and MD orchards and with white, red, and orange traps. Seasonal Comparisons of the Clear Delta Trap. SigniÞcant differences were found in moth catches between the clear and white delta traps in 2008 and clear and orange delta traps in 2009. The mean [SE] weekly total moth catch over the 8-wk study in 2008 was two-fold higher in clear (48.1 [3.8]) versus white (23.3 [2.6]) delta traps baited with PE-PH (Fig. 1a). However, a signiÞcant interaction was found between the week of the study and trap type (F7, 96 ⫽ 3.64, P ⬍ 0.01). Tests on simple effects, i.e., comparison of trap type separately for each week found signiÞcant differences on four dates (clear ⬎ white), primarily during the peak period of the second generation moth ßight (Fig. 1a). Mean (SE) weekly female moth catch was signiÞcantly greater in the clear (1.4 [0.3]) than white (0.6 [0.2]) delta trap over this time period, F1, 96 ⫽ 10.40, P ⬍ 0.01 (Fig. 1b). Female catch varied signiÞcantly over time (F7,96 ⫽ 13.64, P ⬍ 0.0001), but
April 2010 Table 2. lures
KNIGHT: INCREASED CATCH OF FEMALE CODLING MOTH
Comparison of the clear vs orange delta trap baited with various combinations of pear ester, acetic acid, and codlemone
Trap
Mean (SE) moths per d
Lure
Clear delta
Orange delta
Two-way ANOVA Clear delta Orange delta Both traps
Pear ester Pear ester ⫹ codlemone Pear ester ⫹ acetic acid Pear ester ⫹ codlemone ⫹ acetic acid Pear ester Pear ester ⫹ codlemone Pear ester ⫹ acetic acid Pear ester ⫹ codlemone ⫹ acetic acid Lure Trap Lure x trap All lures Pear ester Pear ester ⫹ codlemone Pear ester ⫹ acetic acid Pear ester ⫹ codlemone ⫹ acetic acid
Male
Female
Total
0.32 (0.02) 1.81 (0.79) 0.64 (0.18) 1.30 (0.26) 0.19 (0.05) 2.43 (0.51) 0.38 (0.12) 1.12 (0.25) F3,21 ⫽ 13.33, P ⬍ 0.0001 F1,21 ⫽ 0.49, P ⫽ 0.49 F3,21 ⫽ 1.27, P ⫽ 0.31 1.10 (0.27) 1.09 (0.27) 0.25 (0.04)b 2.12 (0.41)a 0.49 (0.11)b 1.21 (0.17)a
0.45 (0.05) 0.26 (0.04) 0.69 (0.16) 0.60 (0.10) 0.06 (0.03) 0.10 (0.02) 0.10 (0.06) 0.10 (0.05) F3,21 ⫽ 1.64, P ⫽ 0.21 F1,21 ⫽ 73.22, P ⬍ 0.0001 F3,21 ⫽ 2.18, P ⫽ 0.12 0.49 (0.06)a 0.09 (0.02)b 0.25 (0.09) 0.18 (0.04) 0.35 (0.14) 0.35 (0.11)
0.78 (0.07) 2.07 (0.80) 1.32 (0.34) 1.90 (0.35) 0.24 (0.02) 2.53 (0.51) 0.49 (0.17) 1.22 (0.27) F3,21 ⫽ 8.22, P ⬍ 0.001 F1,21 ⫽ 3.83, P ⫽ 0.06 F3,21 ⫽ 1.79, P ⫽ 0.18 1.58 (0.27) 1.18 (0.28) 0.51 (0.12)c 2.30 (0.45)a 0.85 (0.23)bc 1.56 (0.24)ab
the interaction of trap type and week was not significant (F7,96 ⫽ 0.81, P ⫽ 0.58). The mean (SE) weekly total moth catch in 2009 did not differ between clear (18.5 [1.7]) and orange (17.8 [1.7]) traps (F1,200 ⫽ 0.13, P ⫽ 0.72; Fig. 2a). Although the weekly total moth catch varied signiÞcantly over time (F16,200 ⫽ 3.87, P ⬍ 0.0001), the interaction of trap type and time was not signiÞcant (F16,200 ⫽ 0.94, P ⫽ 0.52). In contrast, the mean weekly catch of female moths in 2009 was signiÞcantly different between trap types (F1,200 ⫽ 10.29, P ⬍ 0.01), with the mean weekly catch two-fold higher in the clear (2.36 [0.37]) versus the orange (1.15 [0.19]) trap (Fig. 2b). The female moth catch varied signiÞcantly over time (F16,200 ⫽ 4.71, P ⬍ 0.0001), but the interaction between time and trap type was not signiÞcant (F16,200 ⫽ 0.56, P ⫽ 0.91). Evaluation of Trap Selectivity. SigniÞcant differences in the catch of several groups of nontarget insects were found among clear and colored delta traps baited with different lures (Table 4). Few nontargets were caught in any of the unbaited traps. SigniÞcant differences in the capture of nontarget moths were found among trap types baited with AA but not with PE or PE-PH. Clear traps baited with AA caught Table 3.
587
greater than four-fold more nontarget moths than other traps (Table 4). No signiÞcant differences in the capture of nontarget dipterans were found among traps in any of the four tests. White traps caught signiÞcantly more nontarget hymenopterans (primarily A. mellifera) than other traps when baited with PE (Table 4). Discussion Establishing effective monitoring programs for female codling moth instead of males would be a more direct approach to predict the seasonal periods of oviposition and the potential risk of fruit injury within orchards. This was clearly shown by the signiÞcantly improved prediction of the start of egg hatch and correlation of moth catch with levels of fruit injury in two previous studies using white delta traps baited with pear ester (Knight and Light 2005c, d). However, pear ester has not been widely adopted, and similar studies with the PE-PH lure in white or orange delta traps have not yet been conducted. Although switching to a clear delta trap baited with the PE-PH lure would double the number of female moths caught, their relative proportion of the total moths in the trap
Comparison of male codling moth catches in clear and orange delta traps baited with sex pheromone
Lure typea
Orchard typeb
Red septa Red septa Grey septa Grey septa Membrane Membrane
Untreated Pheromone-treated Untreated Pheromone-treated Untreated Pheromone-treated
Mean (SE) moth catch per d Colored deltac
Clear delta
2.2 (0.7) 0.26 (0.14) 8.1 (1.1) 0.17 (0.05) 3.1 (0.5) 5.8 (0.9)
1.8 (0.5) 0.41 (0.14) 8.9 (1.4) 0.21 (0.05) 3.6 (0.8) 6.9 (1.2)
t-test t18 ⫽ 0.39, P ⫽ 0.70 t18 ⫽ 0.80, P ⫽ 0.43 t28 ⫽ 0.16, P ⫽ 0.87 t18 ⫽ 0.76, P ⫽ 0.46 t17 ⫽ 0.59, P ⫽ 0.57 t18 ⫽ 0.51, P ⫽ 0.62
a Lures tested in sex pheromone-treated orchards were the red septa, Pherocon CM 10X (Tre´ ce´ ); gray septa, Pherocon Megalure (Tre´ ce´ ); and membrane, Biolure 10X (Suterra). Lures tested in untreated orchards were the red septa, Pherocon CM 1X (Tre´ ce´ ); gray septa, Pherocon L2 (Tre´ ce´ ); and membrane, Biolure 1X (Suterra). b Pheromone-treated orchard was treated with CheckMate CM XL1000 at a rate of 500 dispensers/ha. c All lures in untreated orchards were tested in orange traps. Grey septa and membrane lures were tested in red traps and red septa were tested in white traps in pheromone-treated orchards, respectively.
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ENVIRONMENTAL ENTOMOLOGY
Fig. 1. Comparison of weekly mean (SE) total (A) and female (B) codling moths caught in clear and white delta traps (n ⫽ 7) during an 8-wk test conducted in an unsprayed apple orchard from 7 July to 1 September 2008. *Statistical signiÞcance on that date, P ⬍ 0.05.
would still remain low, and pest managers might remain unwilling to sex moths (Hawkins and Hilton 2008). Alternative methods to monitor female codling moth population densities, such as the use of bait and light traps have serious constraints which have limited their use (cost, nonselectivity, and ease of servicing). The oil-coated clear panes baited with pear ester are low-cost traps; but they require frequent replacement and are cumbersome to service in the Þeld (Knight 2010). The comparable performance of a clear delta trap baited with PE⫹AA to oil-coated pane traps creates a new opportunity to develop monitoring of female moth density for codling moth management. One beneÞt is that these traps catch nearly equal numbers of males and females so moth sexing might not be needed. However, the nonselectivity of acetic acid lures for large nontarget moths in some orchards may require more frequent replacement of sticky liners. Further studies to assess and compare this trap-lure combination with the current use of white or orange traps baited with PE-PH, especially in MD orchards is warranted. Meanwhile, studies should strive to further improve the efÞciency of traps. Color seems to be an important factor affecting the performance of traps for both male and female codling moth. Traps that have minimum reßectance at wavelengths ⬍560 nm catch signiÞ-
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Fig. 2. Comparison of weekly mean (SE) total (A) and female (B) codling moths caught in clear and orange delta traps placed in seven apple orchards during a 17-wk test from 5 May to 2 September 2009.
cantly more male moths than white traps (Knight and Milczky 2003, Knight and Fisher 2006). However, the importance of trap color is not similar for male and female codling moth (Knight and Fisher 2006, Knight 2010). This difference may be caused by temporal differences in the activity of each sex during the crepuscular period (Knight and Light 2005c) or differences in the orientation behaviors of males to sex pheromone versus females to host plant or food volatile lures. Moth catch on pane traps is hypothesized to be caused by a passive interception of moths ßying within the canopy (Weissling and Knight 1994). Moth capture with delta-shaped traps requires that moths either ßy into or land on and walk inside a deÞned space (Knight et al. 2002a). Unfortunately, female codling mothÕs orientation response to pear ester has not been well studied. Females have not exhibited close orientation to point sources in ßight tunnel tests (Ansebo et al. 2004, Yang et al. 2005, Sauphanor et al. 2007). Instead, studies have recorded female moth catch in baited traps only after extended, unsupervised time periods (Reed and Landolt 2002, Knight and Fisher 2006, Landolt et al. 2007). Further improvements in the design of traps baited with host volatiles or food lures will likely require more complete understanding of female orientation and response to these traps. The attractiveness of pear ester for female codling moth has fueled studies to develop lure and kill systems (Knight and Light 2001). Preliminary studies
April 2010
KNIGHT: INCREASED CATCH OF FEMALE CODLING MOTH
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Table 4. Comparison of non-target captures in delta traps of different colors unbaited or baited with pear ester, pear ester ⴙ codlemone, or acetic acid Nontargetsa
Lure, test date Unbaited, 11Ð18 Aug. Pear ester, 18Ð27 Aug. Pear ester ⫹ codlemone, 1Ð16 Sept. Acetic acid, 20Ð30 Sept.
Lepidopteran Dipteran Hymenopteran Lepidopteran Dipteran Hymenopteran Lepidopteran Dipteran Hymenopteran Lepidopteran Dipteran Hymenopteran
Mean (SE) catch per trap Clear
Orange
White
Red
Kruskal-Wallis ANOVA of ranks
0.1 (0.1) 0.0 (0.0) 0.0 (0.0) 0.0 (0.0) 0.2 (0.1) 0.4 (0.2)ab 1.2 (0.4) 1.0 (0.4) 0.2 (0.2) 3.3 (0.9)a 1.1 (0.4) 0.3 (0.2)
0.0 (0.0) 0.2 (0.1) 0.1 (0.1) 0.0 (0.0) 0.7 (0.5) 0.1 (0.1)b 0.3 (0.2) 1.1 (0.5) 0.1 (0.1) 0.7 (0.3)b 1.6 (0.6) 0.3 (0.2)
0.0 (0.0) 0.2 (0.1) 0.2 (0.1) 0.2 (0.1) 0.6 (0.2) 1.2 (0.4)a 0.3 (0.2) 0.9 (0.4) 0.8 (0.6) 0.7 (0.3)b 1.0 (0.4) 0.4 (0.3)
0.3 (0.2) 0.2 (0.1) 0.0 (0.0) 0.0 (0.0) 0.4 (0.3) 0.0 (0.0)b 0.2 (0.1) 0.6 (0.2) 0.0 (0.0) 0.4 (0.2)b 0.8 (0.4) 0.2 (0.1)
F3,36 ⫽ 2.40, P ⫽ 0.08 F3,36 ⫽ 0.75, P ⫽ 0.53 F3,36 ⫽ 1.32, P ⫽ 0.28 F3,36 ⫽ 2.25, P ⫽ 0.10 F3,36 ⫽ 1.33, P ⫽ 0.28 F3,36 ⫽ 5.04, P ⬍ 0.01 F3,36 ⫽ 1.99, P ⫽ 0.13 F3,36 ⫽ 0.12, P ⫽ 0.94 F3,36 ⫽ 0.76, P ⫽ 0.52 F3,36 ⫽ 7.59, P ⬍ 0.001 F3,36 ⫽ 0.22, P ⫽ 0.88 F3,36 ⫽ 0.09, P ⫽ 0.97
Row means followed by a different letter were signiÞcantly different, P ⬍ 0.05. a Data were summarized by insect order. Lepidopterans included mostly noctuids, pyralids, and tortricids. Dipterans included mostly muscids. Hymenopterans were primarily vespids and the honeybee, Apis melliferac L.
showed that the use of insecticide-treated killing stations baited with pear ester could be effective in reducing fruit injury during the Þrst moth ßight (Knight et al. 2002b), but later in the season, few females contacted traps (Knight 2005). Similarly, mass trapping studies have not been effective because too few female moths were captured using several standard white paper or plastic trap designs (Light et al. 2003). Further development of a clear trap baited with lures more attractive for females, such as PE⫹AA, may lead us closer to the goal of developing effective low-cost and low maintenance designs for mass trapping and lure and kill strategies for codling moth. Acknowledgments I thank C. Temple and D. Larson, USDAÐARS, Wapato, WA, for help in setting up the Þeld trials, and T. Larsen (Suterra, Bend, OR) and B. Lingren (Tre´ ce´ , Adair, OK) for providing traps and lures. Helpful reviews of the manuscript were provided by C. Myers, USDAÐARS, Kearneysville, WV; E. Fuentes-Contreras, Universidad de Talca, Talca, Chile; O. Kovanci, Uludag University, Turkey; and G. Loeb, Cornell University, Geneva, NY.
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