DOI: 10.1111/j.1570-7458.2009.00925.x Monitoring Amyelois transitella males and females with phenyl propionate traps in and

Charles S. Burks1*, Bradley S. Higbee2,L.P.S.Kuenen1 &DavidG.Brandl1 1USDA-ARS, San Joaquin Valley Agricultural Sciences Center, Parlier, CA, USA, and 2Paramount Farming Company, Bakersfield, CA, USA Accepted: 14 September 2009

Key words: navel orangeworm, California, semiochemical, female attractant, , , glass dispenser, Prunus dulcis, Pistacia vera

Abstract We examined phenyl propionate as an attractant for trapping navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae) adults, with the objective of developing a method of trapping both sexes more effectively than with meal. Two initial experiments maximized the total number of adults captured using phenyl propionate released from glass vials with cotton wicks. A third exper- iment compared the numbers of males and females captured using these glass dispensers in either bucket or sticky traps. The glass vial dispensers captured more adults than 0.1% phenyl propionate in water (as both attractant and killing agent), and far more adults were captured with glass vial phenyl propionate dispensers than with almond meal. On rare occasion, the glass vial dispensers captured as many adults as traps baited with virgin females, but usually phenyl propionate in glass vials captured fewer adults than virgin-baited traps. Glass vial phenyl propionate dispensers were equally effective in sticky traps or bucket traps. The majority of females captured were mated, and the proportion of males captured increased over time within flights (generations). We conclude that phenyl propionate released from glass vials captured A. transitella adults more effectively than currently available options, and will be useful in research projects where capturing intact adults and comparing mating status are important. Developing a cost-effective phenyl propionate-based alternative to the egg traps currently used for commercial monitoring will be more difficult.

Zalom et al., 2009). When chemical control is necessary, Introduction trapping data are used in conjunction with degree day The navel orangeworm, Amyelois transitella (Walker) models to time application targeting the overwintering (Lepidoptera: Pyralidae), is highly polyphagous and a generation (first flight, March–May) and⁄ or the succeed- primary pest of almonds, Prunus dulcis (Mill.) D.A. ing generation (second flight, June–July) (Zalom et al., Webb (Rosaceae), and pistachios, Pistacia vera L. 2009). In pistachios these data and models are used to time (Anacardiaceae) (Bentley et al., 2009; Zalom et al., 2009). treatment against the third flight (Bentley et al., 2009). It is also economically important in walnuts, Mating disruption has recently been registered for use L. (Juglandaceae) (Pickel et al., 2009), and figs, Ficus carica against A. transitella in almonds, pistachios, walnuts, and L. (Moraceae) (Burks & Brandl, 2005). In the southern San figs. High-volume timed release aerosol dispenser (Puffer Joaquin Valley (CA, USA), A. transitella is more abundant NOW; Suterra, Bend, OR, USA) is the only dispenser type in mature pistachios compared to almonds (Burks et al., available. Data to date suggest that, in established orchards, 2008), and it is multivoltine in both crops. mating disruption is more likely to provide greater benefit Management of A. transitella damage in almonds and in almonds then in pistachios (Higbee & Burks, 2008). pistachios has long emphasized cultural practices, supple- Various monitoring methods have been used in mented with insecticides, if necessary (Bentley et al., 2009; research on control of A. transitella damage, but the egg trap is currently the standard commercial tool for moni- toring and timing treatments (Rice, 1976; Rice et al., 1984; *Correspondence: Charles S. Burks, USDA-ARS, 9611 S. Riverbend Van Steenwyk & Barnett, 1985; Kuenen et al., 2008). While Avenue, Parlier, CA 93648, USA. E-mail: [email protected] attractive blends of pheromone components have been

No Claims to Original US government works Entomologia Experimentalis et Applicata 133: 283–291, 2009 Journal compilation 2009 The Netherlands Entomological Society 283 284 Burks et al. identified for A. transitella (Leal et al., 2005; Millar & Kue- listed previously are found widely in nature and can origi- nen, 2005), incorporating these components into a lure nate from plant breakdown products (Diaz et al., 1998), that is attractive for more than one or two nights has pro- but we are unaware of any study associating phenyl propi- ven difficult (LPS Kuenen, pers. obs.). Unmated females onate specifically with A. transitella host material. Phenyl are therefore still used as a pheromone source for monitor- propionate has also been demonstrated as an attractant for ing this species for experimental purposes (Burks et al., Phyllophaga spp. (Crocker et al., 1999). A similar phenolic 2008; Higbee & Burks, 2008). Traps containing almond compound, 2-phenylethanol, has been found in fungus- meal and almond oil (used as oviposition attractant in egg infested commodities and shown to be attractant to Ory- traps) have also been shown to capture A. transitella zaephilus surinamensis (L.) (Pierce et al., 1991) and Ecto- females, but they are not used commercially because egg myelois ceratoniae (Zeller) (Cosse´ et al., 1994), which are traps are cheaper, easier to use, and do not share the prob- also scavenger species associated with dried fruit and lem of capturing species resembling A. transitella (Rice stored products. et al., 1976). The objectives of the current study were to: (1) compare Mating disruption treatments targeted against other the effectiveness of phenyl propionate as an attractant Lepidoptera have, in some cases, resulted in reduced dam- when used either in a water trap as a 0.1% aqueous solu- age despite the presence of mated females in the treatment tion or when released from a saturated cotton wick; and plot (Rice & Kirsch, 1990; McLaughlin et al., 1994; Agnello (2) to compare, in almonds and pistachios, the number, et al., 1996; Kovanci & Walgenbach, 2005; Knight, 2006, sex, and mating status of A. transitella captured with phe- 2007). It has been therefore proposed that reduced moth nyl propionate and with almond meal. Traps baited with fecundity due to either delayed or decreased multiple mat- virgin females or with almond meal were used to provide ing, caused by mating disruption, is an important factor in estimates of relative abundance A. transitella. its efficacy in some species (Vickers, 1997; Jones & Aihara- Sasaki, 2001; Knight, 2006, 2007). For investigation of this Materials and methods effect, compounds attractive to both sexes and whose attractiveness is not completely eliminated by pheromone Two experiments were conducted to compare the number permeation have proven useful; e.g., terpinyl acetate bait of adults captured using phenyl propionate (propionic traps for Graphilita molesta (Busck) (Rice & Kirsch, 1990; acid phenyl ester, CAS 637-24-4; TCI America, Portland, Kovanci & Walgenbach, 2005) and (E,Z)-2,4-decadienoate OR, USA) dispensed using either as a 0.1% (wt ⁄ vol) solu- (pear ester) for Cydia pomonella L. (Knight, 2006, 2007). tion, as reported previously (Price et al., 1967), or using a Phenyl propionate is a possible candidate for such a role in glass vial dispenser containing neat phenyl propionate and characterizing the response of A. transitella to mating dis- a cotton wick. A third experiment compared, between ruption (Price et al., 1967). almond meal and phenyl propionate dispensed from glass In some cases mating disruption has been implemented vials, the number and sex of adults and mating status of over the entire portion of the year that the target pest is females. In each of these experiments wing traps baited active, whereas in other cases it has been targeted against with virgin females were used as an index of seasonal abun- selected generations in a multivoltine pest (Rice & Kirsch, dance. An overview of lures and trap types used in these 1990; Vickers, 1990; Trimble et al., 2001; Atanassov et al., three experiments is provided in Table 1. 2002; Pickel et al., 2002). As the number of spermato- Experiment 1 was conducted in March and April 2004 phores per A. transitella female varies over the growing in an orchard of Kerman pistachios in Madera County, season (Landolt & Curtis, 1991), examining the abundance CA, USA (3700¢N, 11957¢W). This experiment com- of mated females and the number of spermatophores per pared the effect of wick length in glass vial phenyl propio- females in the presence of mating disruption would be use- nate dispensers, and compared these dispensers with ful for assessing its effect against A. transitella at various phenyl propionate in a 0.1% (wt ⁄ vol) solution in water times of the year. which served as both attractant and a killing solution. A Phenyl propionate is one of several compounds demon- completely randomized design was used to compare six strated as attractants for A. transitella (Price et al., 1967), treatments (Table 1). Treatments were randomly assigned but its role in the chemical ecology of this species has not to trees ca. 50 m apart within one of five orchard rows ca. been established. Phenyl propionate, ethyl phenylacetate, 50 m apart. Traps were suspended from branches at and phenyl isobutyrate captured A. transitella males and 1.5–2 m above the ground, approximately midway females when placed in the field in water traps (Price et al., between the trunk and the edge of the canopy, on the north 1967). That paper, however, did not provide a rationale side of the tree. Trap liners and baits were changed weekly for materials screened. Aromatic compounds such as those between 9 March and 13 April 2004, and trap positions Trapping Amyelois transitella with phenyl propionate 285

Table 1 Traps and lures used in experiments optimizing Amyelois (Kuenen et al., 2005). The 0.1% phenyl propionate solu- transitella adults captured with phenyl propionate (PP), and tion was tested using 473 ml plastic containers (76 mm comparing PP with other lures high, 89 mm diameter at the base, and 111 mm diameter at the mouth) (PK16S-C; Fabrical, Kalamazoo, MI, USA) Experiment Treatment Trap description suspended under modified Pherocon 1c trap tops (hereaf- 1 1 Cup under wing trap top ter ‘cup traps’), as described by Curtis & Clark (1984). Cup containing 0.1% PP in water traps contained 0.1% (vol⁄ vol) tween-20 emulsifier in 2 Vial inside wing trap with 250 ml water. The total number of A. transitella adults was technical PP and 5-mm wick counted on the wing trap liners, and moths were strained 3 Vial inside wing trap with from cup traps, cleared by immersion in 10% (wt ⁄ vol) technical PP and 10-mm wick potassium hydroxide for 12 h, and then stored in 70% 4 Vial inside wing trap with ethanol pending identification of species and determina- technical PP and 15-mm wick 5 Empty vial inside wing tion of sex and mating status of females. Because the objec- trap (negative control) tive of experiment 1 was to optimize the number of A. 6 Virgin females inside wing trap transitella adults captured, sex and mating status were 2 1 Cup under wing trap top determined for the phenyl propionate cup traps only. containing 0.1% PP in water Experiment 2 was conducted from May to October 2 Cup under wing trap with water, 2004 at the same location as experiment 1. Treatments for female-baited this experiment are described in Table 1. As in experiment 3 Vial inside wing trap containing 1, treatments were re-randomized between positions technical PP (clear) (trees) every 2 weeks. Based on the previous experiments, 4 Vial inside wing trap containing 10 mm cotton wicks were used with vials containing phe- technical PP (amber) nyl propionate. To improve convenience, clear amber vials 5 Virgin females inside wing trap 6 Unbaited wing traps covered with aluminum foil (used in experiment 1) were 7 Cup under wing trap top with compared with uncovered amber vials. Cup traps without water only phenyl propionate were used with virgin females because 3 1 Wing trap baited with virgin females previous experience indicated that saturation was an issue 2 Delta trap baited with almond meal with wing traps using sticky liners. A cup trap containing 3 Delta trap baited with vial only 0.1% tween-20 was tested to determine whether water containing technical PP itself was attractive to adults, and an unbaited wing trap 4 Bucket trap baited with was tested to determine the number of adults captured almond meal without any attractant. Spacing between treatments (traps) 5 Bucket trap baited with vial was as described above. Attractants, liners of wing traps, containing technical PP and water in cup traps were changed every week. Experiment 3 compared the number of A. transistella males and females and the mating status of females within blocks were re-randomized every 2 weeks. Three between almond meal (Liberty Vegetable Oil Company, ml of phenyl propionate was placed in clear 15 · 45 mm City of Commerce, CA, USA) and phenyl propionate in cylindrical glass vials (Kimble Chase, Vineland, NJ, USA). amber glass vial dispensers with 10-mm wicks. This experi- One end of a 9 · 100 mm cotton dental wick (Richmond ment was conducted from March to November 2007 in Dental, Charlotte, NC, USA) was inserted all the way into and almond orchards in Kern County, CA, USA the vial, and cut such that the cotton extended over top of (3535¢N, 11909¢W) using treatments described in the vial by 5, 10, or 15 mm, and the vials were covered with Table 1. The almond meal and phenyl propionate treat- aluminum foil. Traps with virgin females as a pheromone ments were compared between orange delta traps (Suterra, source used 1–2-day-old moths from a laboratory colony Bend, OR, USA) and white, yellow, and green bucket traps established in 1966, as described by Burks & Brandl (multi-colored Unitraps; Great Lakes IPM, Vestaburg, MI, (2004). Phenyl propionate vials and plastic mesh bags con- USA), because if the delta traps were more effective, there taining three virgin A. transitella females were suspended was potentially a trade-off between greater numbers of inside white Pherocon 1c wing traps that were slightly adults from a sticky traps vs. adults in better condition for modified for ease of maintenance, using bending of the dissection from a bucket trap. In this experiment, virgin wire frame rather than the provided plastic spacer tubes to females were suspended inside orange wing traps (Suterra maintain the space between the trap top and bottom LLC). Almond meal (Liberty Vegetable Oil Company) 286 Burks et al.

(25 g) was placed in a heat-sealed organdy bag traps containing phenyl propionate (treatments 3 and 5, (3.8 · 6.4 cm internal dimensions) suspended inside delta Table 1). In this analysis the response variable was the and bucket traps. The almond orchard contained the vari- number of adults per trap and the predictor variables were eties Nonpareil and Monterey planted in interspersed treatment, week, and their interaction. A second GLM rows, and the pistachio orchard was planted entirely with analysis with a binomial distribution was used to examine the Kerman variety. The treatments were arranged in four the sex ratio of adults captured over this period, in this case replicated blocks, ‡800 m apart. Within each block, a wing the response variable was ‘females ⁄ total adults’ and the trap baited with virgin females was placed in the central predictors were treatment, week, and their interaction. position. One each of the four possible combinations of Non-parametric procedures were also used with experi- bucket trap or delta trap baited with almond meal or phe- ments 1 and 3. In experiment 1, contingency table analysis nyl propionate was assigned to positions 30 m from the with Pearson’s v2 was used to compare sex ratio of adults center trap in each of the cardinal directions. Attractants from phenyl propionate cup traps between the second and and liners were changed and data collected at weekly inter- third 2-week randomization periods, and in experiment 2 vals from 14 February to 1 October 2007, with the excep- the Kruskal–Wallis ANOVA was used to compare almond tion of 23 August 2007. Sex and mating status of females meal and phenyl propionate treatments (treatments 2–5; were determined for all A. transitella on wing trap liners Table 1) in experiment 3. A critical value of a =0.05was and from bucket traps. Traps were hung in the lower can- used for all tests of significance, and the Tukey, Bonferoni, opy 1.5–2 m from the ground. and Nemenyi adjustments for multiple comparisons were used with ANOVA, GLM, and Kruskal–Wallis, respec- Statistical analysis tively (Zar, 1999). Means and standard errors presented in Data were analyzed using the SAS System (Cary, NC, figures and tables are of untransformed data. USA). Treatments were excluded from statistical analysis for control and other treatments in which the majority of Results observations were counts of 0 (Reeve & Strom, 2004). Experiment 1 was analyzed with ANOVA (Proc GLM). In experiment 1, wing traps baited with an empty vial The response variable was a (x + 0.5) transformation of (treatment 5; Table 1) had 0.1 adults per trap per 2-week moths per trap per 2-week period, and predictor variables randomization, and were not included in the analysis. The were treatment (Table 1), randomization period, and their ANOVA model was significant (F14,74 = 104, P<0.001), as interaction. Empty vials (treatment 5, Table 1) were were effects of treatment (F4,74 = 171, P<0.001), 2-week excluded from analysis because most counts were 0. Gen- randomization period (F2,74 = 349, P<0.001), and their eralized linear models (GLM) (Proc GENMOND) (Agres- interaction (F8,74 = 11, P<0.001). Over the entire experi- ti, 2007) were used with experiments 2 and 3 because ment, wing traps with phenyl propionate released from transformations were not sufficient to stabilize variance glass vials captured significantly more moths than cup for those data. For experiment 2 a GLM analysis with nega- traps with 0.1% phenyl propionate, but significantly fewer tive binomial distribution was used to compare the num- moths than wing traps baited with virgin females ber of moths captured by the treatments over the entire (Table 2). Wick length in vial dispensers for phenyl propi- experiment. In this analysis, the response factor was moths onate had no effect on the number of adults captured. per trap per 2-week randomization period, and the predic- tors were treatment (Table 1), randomization period, and Table 2 Amyelois transitella adults (mean ± SE) captured their interaction. Empty wing traps, water only cup traps, between 9 March and 20 April 2004, in traps baited with phenyl and cup traps with 0.1% phenyl propionate (treatments 1, propionate (PP) or virgin females 5, and 7; Table 1) were excluded from analysis because most counts were 0. After this analysis found no significant No. adults per difference between adults captured in phenyl propionate trap per 2-week Trap type Bait randomization dispensed from clear and amber vials, these treatments were pooled and another GLM with negative binomial dis- Cup PP (0.1% in water) 10.5 ± 2.4a tribution was used to examine differences in moths per Wing Vial with PP, 5-mm wick 66.9 ± 12.7b trap between 2-week randomization periods (i.e., moths Vial with PP, 10-mm wick 64.8 ± 13.6b per trap as response variable and randomization period as Vial with PP, 20-mm wick 73.4 ± 13.2b Virgin females 143.2 ± 14.7c the single predictor variable). For experiment 3, a GLM analysis with a negative binomial distribution was used to Means followed by a different letter are significantly different examine differences in adults per trap between weeks in (ANOVA: P<0.05). Trapping Amyelois transitella with phenyl propionate 287

Adults per trap for the pooled phenyl propionate vial captured <0.2 adults per trap per week over the entire traps for the 6 weeks comprising the three randomization experiment. There were significant effects due to treatment periods in experiment 1 are plotted in Figure 1, along with (v2 = 635.92, d.f. = 3, P<0.001), 2-week randomization weekly adults per trap for the cup traps containing 0.1% period (v2 = 268.12, d.f. = 10, P<0.01), and their interac- phenyl propionate and the traps baited with virgin females. tion (v2 = 131.98, d.f. = 30, P<0.001). Wing traps baited Although at times phenyl propionate released from glass with amber and clear vials captured 3.6 ± 0.44 vials captured very few adults, similar to the cup traps, for (mean ± SE) and 3.2 ± 0.44 adults per 2-week randomi- 1 week the number of moths captured in the phenyl propi- zation period, respectively, while wing trap baited with vir- onate vial traps are similar to the number captured in traps gin females captured 109 ± 6.6 adults per randomization baited with virgin females. This variability in week-to- period, and water-filled cup traps baited with virgin week number of adults captured between trap types is females captured 182 ± 21 adults per randomization per- consistent with the highly significant interaction of treat- iod. The difference between moths captured in traps baited ment*randomization. with amber or clear vials was not significant (P>0.05), The sex ratio of adults captured in 0.1% phenyl propio- whereas all other differences were highly significant nate cup traps also changed over the course of experiment (P<0.001). 1, from 0.6 males per female in the second period to 1.7 Over the course of experiment 2, the number of adults males per female in the third period (Table 3). These ratios captured in traps baited with glass vials containing phenyl were significantly different (v2 = 9.51, d.f. = 1, P<0.01). propionate and with virgin females fluctuated (Figure 2). Of the females, 98% were mated. Prior to August the virgin-baited cup traps captured simi- In contrast to experiment 1, very few adults were cap- lar numbers of adults compared to virgin-baited wing tured in cups containing 0.1% phenyl propionate in exper- traps, which are more susceptible to saturation. In August iment 2. That treatment and negative control treatments and September; however, far more adults were captured in containing water only or empty vials only (treatments 1, 5 virgin-baited cup traps than in virgin-baited wing traps and 6; Table 1) were excluded from analysis because each (Figure 2A). A second GLM examining adults per trap in the pooled phenyl propionate vial treatments (treatments 3 and 4; Table 1) as a function of 2-week period was significant (v2 = 107, d.f. = 10, P<0.001). Peak numbers of adults in the phenyl propionate traps on 15 June, 3 August, and 20 September were each significantly greater

Figure 1 Amyelois transitella adults (mean ± SE) captured weekly in March and April, 2004, in cup traps baited with 0.1% phenyl propionate (PP) in solution (black triangles), wing traps baited with glass vial PP dispensers (white circles), and wing traps baited with virgin females (black circles).

Table 3 Amyelois transitella adults captured in cup traps between 9 March and 20 April 2004, in traps baited with phenyl propio- nate

Two-week period starting Figure 2 Effect of attractant and trap type on the number of Sex, mating status 9 March 23 March 6 April Amyelois transitella adults (mean ± SE) per trap per 14 days between May and October 2004. (A) Adults in cup traps (black Male 0 37 34 circles) and wing traps (white circles), both baited with virgin Female, mated 3 61 20 females. (B) Adults in wing trap baited with glass vial phenyl Female, unmated 0 2 0 propionate dispensers. For weeks indicated by asterisks, the There is a significant difference in the sex ratio between the sec- number of adults captured was significantly different from the ond and the third period (Pearson v2: P<0.01). preceding week (generalized linear model: P<0.05). 288 Burks et al. than the numbers of adults captured the preceding 2-week periods (P<0.005) (Figure 2B). Flights in the study locations in 2007 were assigned based on weekly fluctuations in males captured in virgin-baited wing traps (data not shown). Fewer A. transitella were captured in almonds compared to pistachios, and very few moths were captured in either crop with traps baited with almond meal Figure 3 Mean (±SE) Amyelois transitella males and females (Table 4). Unlike experiment 1, few adults were cap- captured weekly between July and September 2007 in traps baited tured with phenyl propionate in pistachios in flight 1, with glass vial phenyl propionate dispensers. and the number of adults captured with phenyl pro- pionate never approached the number captured in female) was significantly different from the preceding week traps baited with virgin females. A non-parametric in the 2nd, 3rd, and last week, i.e., on 26 July, 26 August, analysis was used to compare the number of adults and 2 September. There was also a significant effect on the captured with almond meal and phenyl propionate sex ratio due to week (v2 = 21.55, d.f. = 6, P<0.01), but because this was of greater interest than the compari- not trap type (v2 = 0.48, d.f. = 1, P = 0.49) or the week* son of adults captured with phenyl propionate and trap interaction (v2 = 3.85, d.f. = 6, P = 0.70). There virgin females. In all cases in which there were were significantly more males than females in the samples significant differences between these two attractants, in August, but not before or after. significantly more adults were captured in traps baited A total of 19 females were recovered from all lures in with phenyl propionate than in traps baited with almonds. Of these, 15 were from phenyl propopionate, almond meal (Table 4). and two were unmated. Of the 250 females recovered from As the majority of adults captured with phenyl propio- phenyl propionate traps in pistachios and dissected, 2% nate in 2007 were captured in pistachios during the third were unmated, 86% had one spermatophore, and 12% flight, weekly changes in sex ratio were examined in greater had two spermatophores; hence, on average we found 1.1 detail in this period. There were significant effects on the spermatophore per female. weekly number of adults per trap due to time (week) (v2 = 43.43, d.f. = 6, P<0.001), but not trap type Discussion (v2 = 3.36, d.f. = 1, P = 0.07) or the week*trap interac- tion (v2 = 2.63, d.f. = 6, P = 0.85). Because the effect of The effectiveness of pure phenyl propionate in a glass trap was not significant, the number of males and females vial ⁄ cotton wick dispenser was compared in experiments 1 captured in the combined phenyl propionate trap types and 2 with the 0.1% phenyl propionate water trap used in (bucket and delta) in flight 3 and the adjacent weeks is a previous study (Price et al., 1967). These glass vial plotted in Figure 3. The total number of adults (male and dispensers clearly captured far more adults than phenyl

Table 4 Amyelois transitella adults Flight (mean ± SE) per trap per week captured Crop Lure Trap 1234in 2007 in almond meal (AM) or phenyl propionate (PP), or virgin female-baited Almond AM Delta 0.03 ± 0.019a 0.00 ± 0.00 0.00 ± 0.00 0.10 ± 0.06 traps in almonds and pistachios Bucket 0.02 ± 0.017a 0.00 ± 0.00 0.05 ± 0.05 0.00 ± 0.00 PP Delta 0.45 ± 0.17b 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00 Bucket 0.27 ± 0.15b 0.08 ± 0.05 0.05 ± 0.05 0.00 ± 0.00 Female Wing 16 ± 4.6 0.13 ± 0.08 0.65 ± 0.65 3.1 ± 0.50 Pistachio AM Delta 0.17 ± 0.019a 0.13 ± 0.08a 0.00 ± 0.00a 0.06 ± 0.06a Bucket 0.05 ± 0.032a 0.00 ± 0.00a 0.05 ± 0.05a 0.44 ± 0.12a PP Delta 0.45 ± 0.042b 1.3 ± 0.64b 27 ± 13.5b 0.81 ± 0.28b Bucket 0.47 ± 0.119b 1.1 ± 0.60b 21 ± 5.9b 1.13 ± 0.63b Female Wing 60 ± 3.8 73 ± 3.5 121 ± 2.7 68 ± 6.3

Means within the same crop and flight followed by a different letter are significantly differ- ent (Kruskal–Wallis ANOVA with Nemenyi test for multiple comparisons: P<0.05). Vir- gin-baited female traps not included in analysis. Trapping Amyelois transitella with phenyl propionate 289 propionate in solution in these tests. In contrast, Price phenyl propionate glass vial dispensers captured the same et al. (1967) captured the equivalent of 170 adults per trap high number of adults as our traps baited with virgin per week in a 3-day test in almonds in early September. females. Peak activity over fewer weeks is also seen often Tests of wick length in experiment 1 and of vial type in when comparing data from virgin female-baited wing experiment 2 were attempts to optimize the glass vial dis- traps and egg traps (CS Burks and BS Higbee, unpubl.). pensers. As these factors proved to make no difference, High activity was seen in first flight and not in third flight these treatments were pooled for examination of seasonal in experiments 1 and 2, and vice versa in experiment 3. changes in trap activity. Traps with virgin females as a Greater trapping intensity is likely why we found defined pheromone source were used as an index of population peaks in experiment 2 despite low activity, but not in abundance in all three experiments. The difference experiment 3 other than flight 3. We hypothesize that the between the virgin-baited wing traps and cup traps in inconsistency between periods of high activity between are August and September in period 2 suggests that abundance first two and third experiments, and between the experi- was higher during this period, but that it was not apparent ments reported here and that of Price et al. (1967) is due in virgin-baited wing traps due to saturation. Water by to phenyl propionate being highly attractive over a small itself has been used as an attractant for trapping other phy- active space relative to pheromone traps. Further research citine moths (Ryne et al., 2002; Nansen et al., 2008). The is, however, required to test this hypothesis. If this idea that low number of adults captured in traps containing only phenyl propionate traps are highly active over a small water and surfactant show that water is not, by itself, active space is correct, then this would suggest within-tree attractive to A. transitella under field conditions. placement has even greater impact on phenyl propionate Phenyl propionate released from glass vial dispensers traps than on pheromone traps (Riedl et al., 1979), and was compared with almond meal in experiment 3 because could be a factor in differences seen between timing and this is the only other attractant that currently permits numbers of adult captured in glass vial phenyl propionate large-scale trapping for A. transitella adults of both sexes traps in 2004 and 2007. or in the presence of mating disruption. This experiment We found a different sex ratio in A. transitella recov- was conducted in both almonds and pistachios, but com- ered from cup traps with 0.1% phenyl propionate in parison data from virgin-baited traps between the almond experiment 1 and adults captured in traps baited with and pistachio sites indicate that abundance was far greater glass vial phenyl propionate dispensers in experiment 3. at the pistachio site than at the almond site. Although a However, in both experiments the ratio of males to tendency to greater abundance of A. transitella in pista- females increased during the flight: in experiment 1 the chios compared to almonds has previously been docu- ratio went from 1:2 in the second 14-day period to 2:1 mented for the Kern County area where experiment 3 was in the third period, whereas in experiment 3 the sex conducted (Burks et al., 2008), we were surprised by the ratio was 1:1 in the first week of flight 3, and then 4:1 in particularly low abundance found in this almond site in subsequent weeks. Despite the lack of attraction of 2007. Despite this low abundance in the almond site, the A. transitella adults to water vapor by itself, as observed flight 1 data from almonds and the data from all flights in in experiment 1, it is possible that the difference in sex pistachios demonstrate that phenyl propionate in vial dis- ratio observed here between phenyl propionate in solu- pensers consistently captured adults far more effectively tion vs. released from dry dispensers has to do with dif- than almond meal. We anticipated the possibility of a ference between the sexes in interactive effects of phenyl trade-off between higher numbers of adults captured in a propionate and water vapor on response. sticky-type (delta) trap vs. recovery of adults more amena- Phenyl propionate, like almond meal, captured few ble for dissection from bucket traps, but there was not a unmated females. Unlike phenyl propionate, almond meal large difference in the number or sex of adults captured captures very few males. We found 2% unmated females between the two trap types. in females captured in pistachios with phenyl propionate. The results presented indicate that experiment 1 The few adults we captured with almond meal do not occurred over most of the first flight, whereas the peaks of allow a useful comparison, but Rice et al. (1976) reported female activity detected with phenyl propionate traps in 93% females collected with almond meal in sticky traps, all experiment 2 represented second, third, and fourth flights mated. In other studies we have ca. 2% males and ca. 2% at that location in 2004. The overall average of adults cap- unmated females in traps baited with almond meal (BS tured in phenyl propionate released from glass vial dis- Higbee & CS Burks, unpubl.). Landolt & Curtis (1991) pensers in experiment 1 was intermediate between that of found >93% mating among 3 552 A. transitella females phenyl propionate from cup traps and traps baited with collected from black-light traps over 3 years, with the virgin females as a pheromone source, but, for 1 week, the number of spermatophores per female <1.0 during June 290 Burks et al. and ‡1.0 before and after. The number of spermatophores Natural Resources, Oakland, CA, USA. Available at: http:// per female in females recovered from phenyl propionate www.ipm.ucdavis.edu/PDF/PMG/pmgpistachio.pdf. traps in experiment 3 is thus similar to that observed in Burks CS & Brandl DG (2004) Seasonal abundance of navel females captured with almond meal and black-light traps orangeworm (Lepidoptera: Pyralidae) in figs and effect of in other studies. peripheral aerosol dispensers on sexual communication. Jour- nal of Science 4: 1–8. In summary, the glass vial phenyl propionate dispensers Burks CS & Brandl DG (2005) Quantitative assessment of insect here are a more practical option compared to black-light pest damage to figs. Online. Crop Management. Available at: traps, almond meal, or phenyl propionate in solution for http://www.plantmanagementnetwork.org/pub/cm/research/ projects in which it is desirable to monitor or examine 2005/figs/. A. transitella adults, and particularly females. Despite cap- Burks CS, Higbee BS, Brandl DG & Mackey BE (2008) Sampling turing more males than females much of the time, glass and pheromone trapping for comparison of abundance of vial phenyl propionate dispensers captured more females Amyelois transitella in almonds and pistachios. Entomologia than almond meal or phenyl propionate in solution. Pro- Experimentalis et Applicata 129: 66–76. cessing samples with traps baited with glass vial dispensers Cosse´ AA, Endris JJ, Millar JG & Baker TC (1994) Identifi- was far simpler than with liquid-based traps. Although we cation of volatile compounds from fungus-infected date did capture non-target with these glass vial dispens- fruit that stimulate upwind flight in female Ectomyelois ceratoniae. Entomologia Experimentalis et Applicata 72: ers, the majority were sarcophagid flies and noctuid moths 233–238. that were easily distinguished from A. transitella.Thisand Crocker RL, Klein MG, Xikui W & Nailon WT Jr (1999) Attrac- the lack of need for a power supply are advantages of trap- tion of Phyllophaga congrua, Phyllophaga crassissima, Phylloph- ping with phenyl propionate over black-light trapping. aga crinita,andCyclocephala lurida (Coleoptera: Scarabaeidae) The primary disadvantage of monitoring with phenyl pro- adults to selected volatile compounds. Southwestern Entomol- pionate released from dry dispensers is the expense and ogist 24: 315–319. volatility of this chemical. These factors, along with the Curtis CE & Clark JD (1984) Pheromone application and low price and large base of experience for almond meal- monitoring equipment used in field studies of the navel baited egg traps as a monitoring tool, will make commer- orangeworm (Lepidoptera: Pyralidae). Journal of Economic cial adaptation of monitoring with phenyl propionate a Entomology 77: 1057–1061. more formidable challenge. Diaz E, Ferrandez A & Garcia JL (1998) Characterization of the hca cluster encoding the dioxygenolytic pathway for initial catabolism of 3-phenylpropionic acid in Escherichia coli K-12. Acknowledgements Journal of Bacteriology 180: 2915–2923. 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