Advances in Attract-and-Kill for Agricultural Pests: Beyond Pheromones.

Attract-and-kill has considerable potential as a tactic in integrated management of pests of agricultural crops, but the use of sex pheromones as attractants is limited by male multiple mating and immigration of mated females into treated areas. Attractants for both sexes, and particularly females, would minimize these difficulties. Volatile compounds derived from plants or fermentation of plant products can attract females and have been used in traps for monitoring and control, and in sprayable attract-and-kill formulations or bait stations. Recent advances in fundamental understanding of insect responses to plant volatiles should contribute to the development of products that can help manage a wide range of pests with few impacts on nontarget organisms, but theory must be tempered with pragmatism in the selection of volatiles and toxicants and in defining their roles in formulations. Market requirements and regulatory factors must be considered in parallel with scientific constraints if successful products are to be developed.

A survey of insect assemblages responding to volatiles from a ubiquitous fungus in an agricultural landscape.

We report here a first survey of insect orientation to fungal cultures and fungal volatiles from a community ecology perspective. We tested whether volatiles from a ubiquitous yeast-like fungus (Aureobasidium pullulans) are broadly attractive to insects in an agricultural landscape. We evaluated insect attraction to fungal cultures and synthetic compounds identified in fungal headspace (2-methyl-1-butanol, 3-methyl-1-butanol, 2-phenylethanol) in a spearmint (Mentha spicata L.) plantation. Three findings emerged: (1) 1,315 insects representing seven orders and 39 species oriented to traps, but 65 % of trapped insects were Dipterans, of which 80 % were hoverflies (Diptera: Syrphidae); (2) traps baited with A. pullulans caught 481 % more insects than unbaited control traps on average, and contained more diverse (Shannon's H index) and species rich assemblages than control traps, traps baited with Penicillium expansum, or uninoculated media; and (3) insects oriented in greatest abundance to a 1:1:1 blend of A. pullulans volatiles, but mean diversity scores were highest for traps baited with only 2-phenylethanol or 2-methyl-1-butanol. Our results show that individual components of fungal headspace are not equivalent in terms of the abundance and diversity of insects that orient to them. The low abundance of insects captured with P. expansum suggests that insect assemblages do not haphazardly orient to fungal volatiles. We conclude that volatiles from a common fungal species (A. pullulans) are attractive to a variety of insect taxa in an agricultural system, and that insect orientation to fungal volatiles may be a common ecological phenomenon.

Volatile emissions from an epiphytic fungus are semiochemicals for eusocial wasps.

Microbes are ubiquitous on plant surfaces. However, interactions between epiphytic microbes and arthropods are rarely considered as a factor that affects arthropod behaviors. Here, volatile emissions from an epiphytic fungus were investigated as semiochemical attractants for two eusocial wasps. The fungus Aureobasidium pullulans was isolated from apples, and the volatile compounds emitted by fungal colonies were quantified. The attractiveness of fungal colonies and fungal volatiles to social wasps (Vespula spp.) were experimentally tested in the field. Three important findings emerged: (1) traps baited with A. pullulans caught 2750 % more wasps on average than unbaited control traps; (2) the major headspace volatiles emitted by A. pullulans were 2-methyl-1-butanol, 3-methyl-1-butanol, and 2-phenylethyl alcohol; and (3) a synthetic blend of fungal volatiles attracted 4,933 % more wasps on average than unbaited controls. Wasps were most attracted to 2-methyl-1-butanol. The primary wasp species attracted to fungal volatiles were the western yellowjacket (Vespula pensylvanica) and the German yellowjacket (V. germanica), and both species externally vectored A. pullulans. This is the first study to link microbial volatile emissions with eusocial wasp behaviors, and these experiments indicate that volatile compounds emitted by an epiphytic fungus can be responsible for wasp attraction. This work implicates epiphytic microbes as important components in the community ecology of some eusocial hymenopterans, and fungal emissions may signal suitable nutrient sources to foraging wasps. Our experiments are suggestive of a potential symbiosis, but additional studies are needed to determine if eusocial wasp-fungal associations are widespread, and whether these associations are incidental, facultative, or obligate.

Body size phenotypes are heritable and mediate fecundity but not fitness in the lepidopteran frugivore Cydia pomonella.

The inheritance and functional roles of quantitative traits are central concerns of evolutionary ecology. We report two sets of experiments that investigated the heritability and reproductive consequences of body size phenotypes in a globally distributed lepidopteran frugivore, Cydia pomonella (L.). In our first set of experiments, we tested the hypotheses that (1) body size is heritable and (2) parental body size mediates egg production and offspring survival. Midparent-offspring regression analyses revealed that body mass is highly heritable for females and moderately heritable for males. The contribution of fathers to estimates of additive genetic variance was slightly greater than for mothers. Egg production increased with mean parental size, but offspring survival rates were equivalent. Based on this result, we tested two additional hypotheses in a second set of experiments: (3) male size moderates female egg production and egg fertility and (4) egg production, egg fertility, and offspring survival rate are influenced by female mating opportunities. Females paired with large males produced more eggs and a higher proportion of fertile eggs than females paired with small males. Females with multiple mating opportunities produced more fertile eggs than females paired with a single male. However, egg production and offspring survival rates were unaffected by the number of mating opportunities. Our experiments demonstrate that body mass is heritable in C. pomonella and that size phenotypes may mediate fecundity but not fitness. We conclude that male size can influence egg production and fertility, but female mate choice also plays a role in determining egg fertility.

Identification and field evaluation of fermentation volatiles from wine and vinegar that mediate attraction of spotted wing Drosophila, Drosophila suzukii.

Previous studies suggest that olfactory cues from damaged and fermented fruits play important roles in resource recognition of polyphagous spotted wing Drosophila flies (SWD), Drosophila suzukii (Matsumura) (Diptera: Drosophilidae). They are attracted to fermented sweet materials, such as decomposing fruits but also wines and vinegars, and to ubiquitous fermentation volatiles, such as acetic acid and ethanol. Gas chromatography coupled with electroantennographic detection (GC-EAD), gas chromatography-mass spectrometry (GC-MS), two-choice laboratory bioassays, and field trapping experiments were used to identify volatile compounds from wine and vinegar that are involved in SWD attraction. In addition to acetic acid and ethanol, consistent EAD responses were obtained for 13 volatile wine compounds and seven volatile vinegar compounds, with all of the vinegar EAD-active compounds also present in wine. In a field trapping experiment, the 9-component vinegar blend and 15-component wine blend were similarly attractive when compared to an acetic acid plus ethanol mixture, but were not as attractive as the wine plus vinegar mixture. In two-choice laboratory bioassays, 7 EAD-active compounds (ethyl acetate, ethyl butyrate, ethyl lactate, 1-hexanol, isoamyl acetate, 2-methylbutyl acetate, and ethyl sorbate), when added singly to the mixture at the same concentrations tested in the field, decreased the attraction of SWD to the mixture of acetic acid and ethanol. The blends composed of the remaining EAD-active chemicals, an 8-component wine blend [acetic acid + ethanol + acetoin + grape butyrate + methionol + isoamyl lactate + 2-phenylethanol + diethyl succinate] and a 5-component vinegar blend [acetic acid + ethanol + acetoin + grape butyrate + 2-phenylethanol] were more attractive than the acetic acid plus ethanol mixture, and as attractive as the wine plus vinegar mixture in both laboratory assays and the field trapping experiment. These results indicate that these volatiles in wine and vinegar are crucial for SWD attraction to fermented materials on which they feed as adults.

Apple and sugar feeding in adult codling moths, Cydia pomonella: effects on longevity, fecundity, and egg fertility.

Attraction of adult codling moths, Cydia pomonella (L.) (Lepidoptera: Tortricidae), to sweet baits has been well documented. However, beneficial effects of sugar feeding on moth fitness have not been demonstrated. Longevity, fecundity, and egg fertility were examined for female/male pairs of moths maintained with the following food regimens: water, sucrose water, honey water, apple juice, apple flesh, or starved, i.e., no food or water provided. Longevity and total fecundity were enhanced in all treatments relative to the starved treatment moths. Sucrose water, honey water, and apple juice treatments yielded the highest longevity, but total fecundity was highest for moths maintained on honey water or apple juice. Total egg fertility did not differ among treatments. However, egg fertility declined more gradually over the female lifespan for the three aqueous solution diets of sucrose water, honey water, and apple juice. Similarly, fecundity per day declined more gradually over time for honey water and apple juice treatments. Performance of moths maintained with apple flesh was generally intermediate between that of moths with water and the three aqueous solution treatments. This suggests that moths benefit from feeding on ripe apple flesh, although apple may be more difficult to ingest or its nutrients less concentrated compared to aqueous solutions. The results presented here may explain attraction of adult moths to sweet baits as well as to odors from ripe fruit, which may be a natural source of food in the fall.

Limoniic Acid and Its Analog as Trap Lures for Pest Limonius Species (Coleoptera: Elateridae) in North America.

Four species of Limonius wireworms (Coleoptera: Elateridae), L. californicus, L. canus, L. infuscatus and L. agonus, are serious crop pests in North America. Limoniic acid, (E)-4-ethyloct-4-enoic acid, has been reported as a sex pheromone component of female L. californicus and L. canus, and a sex attractant for male L. infuscatus. In the same study, both limoniic acid and the analog (E)-5-ethyloct-4-enoic acid were highly attractive in field experiments. Moreover, six carboxylic acids in headspace volatiles of Limonius females elicited responses from male antennae but were not tested for behavioral activity. Here, we report trap catch data of Limonius spp. obtained in field experiments at 27 sites across North America. All four Limonius species were attracted to limoniic acid and to the analog but not to the carboxylic acids. Adding these carboxylic acids to limoniic acid, or to the analog, reduced its attractiveness. In dose-response studies, trap lures containing 0.4 mg or 4 mg of limoniic acid afforded large captures of L. californicus and L. infuscatus. Neither limoniic acid nor the analog were deterrent to other elaterid pest species. The broad attractiveness of limoniic acid to Limonius spp., and its non-deterrent effect on heterogeners, may facilitate the development of generic pheromone-based monitoring and management tools for multiple click beetle species.

The Venom Compound N-(3-methylbutyl)acetamide Attracts Several Polistes (Fuscopolistes) Species (Hymenoptera: Vespidae).

Polistes paper wasps in the Fuscopolistes subgenus (Hymenoptera: Vespidae) can be serious pests when they swarm at tall man-made structures. Chemical attractants may be useful to trap such paper wasps when they achieve pest status. Polistes venom has been shown to elicit a variety of behavioral responses in congeneric wasps, making it a source for potential chemical attractants. The compound N-(3-methylbutyl)acetamide is a principal volatile component in the venom of many female vespid wasps, including numerous Polistes species. We report the presence of N-(3-methylbutyl)acetamide in autumn gynes of Polistes metricus Say, Polistes bellicosus Cresson, and Polistes dorsalis (F.), as well as workers of Polistes aurifer (Saussure), P. bellicosus, P. metricus, and P. dorsalis. In field tests conducted in Florida, Georgia, South Carolina, and Washington, N-(3-methylbutyl)acetamide attracted male and female P. aurifer and P. metricus, as well as male P. dorsalis and P. bellicosus. Thus, N-(3-methylbutyl)acetamide may be a useful lure for trapping these paper wasps in pest situations.

Identification of a sex attractant pheromone for male winterform pear psylla, Cacopsylla pyricola.

Pear psylla, Cacopsylla pyricola (Förster) (Hemiptera: Psyllidae), a major economic pest of pears, uses a female-produced sex attractant pheromone. We compared the chemical profiles obtained from cuticular extracts of diapausing and post-diapause winterform males and females to isolate and identify the pheromone. Post-diapause females produced significantly more of the cuticular hydrocarbon, 13-methylheptacosane, than post-diapause males and diapausing females. In olfactometer assays, conspecific males were attracted to synthetic racemic 13-methylheptacosane, whereas females were not, indicating that the behavioral response to this chemical is sex-specific. Furthermore, 13-methylheptacosane was as attractive to males as a cuticular extract of females, suggesting that this chemical was largely responsible for the female attractiveness. A field study showed that males but not females were attracted to 13-methylheptacosane, confirming the olfactometer results. This study provides evidence that 13-methylheptacosane is a sex attractant pheromone for C. pyricola winterform males. This is the first identification of a sex pheromone in the Psylloidea. Our results open the path to developing monitoring tools and possibly new strategies for integrated pest management of this insect.

Attraction of Cacopsylla pyricola (Hemiptera: Psyllidae) to female psylla in pear orchards.

The pear psylla, Cacopsylla pyricola (Förster), is a major economic pest of pears in North America and Europe. Laboratory studies have shown that males of both the summerform and winterform morphotypes in this species are attracted to volatiles given off by females. This study tested whether attraction by males to females can be shown in the field. We showed that males had a clear preference for sticky traps that had been baited with live females compared with traps baited with live males or traps that were left unbaited. Female C. pyricola did not exhibit a preference among the three types of trap treatments. These results were obtained for both morphotypes. Trap catch was also monitored at 2-h intervals to assess whether capture of males on female-baited traps varied with time of day. Summerform male C. pyricola were caught in highest numbers between 1,445 and 1,645 hours, whereas winterform males were most often captured between 1,300 and 1,700 hours on traps baited with females. In both trials, there was again a significant preference by males for the female-baited traps compared with unbaited traps. Long-term practical benefits of the methods developed here provide a platform for the development of more effective monitoring tools, use in mating disruption, or development of lure and kill technologies.

Use of shaking treatments and preharvest sprays of pyrethroid insecticides to reduce risk of yellowjackets and other insects on Christmas trees imported into Hawaii.

Insects are commonly found by Hawaii's quarantine inspectors on Christmas trees imported from the Pacific Northwest. To reduce the risk of importing yellowjacket (Vespula spp.) queens and other insects, an inspection and tree shaking certification program was begun in 1990. From 1993 to 2006, the annual percentage of shipped containers rated by Hawaii quarantine inspectors as moderately or highly infested with insects was significantly higher for manually shaken trees than for mechanically shaken trees. Between 1993 and 2001, 343 insect species in total were recovered from Christmas trees. Live western yellowjacket [Vespula pensylvanica (Saussure)] queens were intercepted both from containers certified as manually shaken and from containers certified as mechanically shaken. The standard manual shaking protocol removed about one-half of the queens from Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] trees that were naturally infested with western yellowjacket queens. We investigated the use of preharvest sprays of permethrin as a complement to shaking procedures used to control yellowjackets and other insects. Western yellowjacket queens and honey bees (surrogates for wasp pests) were exposed to Noble fir foliage that had been sprayed in the field with permethrin > 6 wk before harvest. Pesticide residues provided complete control (moribundity or mortality) in both species. The sprays did not affect needle retention or quality of Noble fir foliage. We conclude that preharvest sprays of pyrethroid insecticides could be used in combination with mechanical shaking to greatly reduce the quarantine risk of yellowjacket queens and other insects in exported Christmas trees.

Field and laboratory responses of male leaf roller moths, Choristoneura rosaceana and Pandemis pyrusana, to pheromone concentrations in an attracticide paste formulation.

Male leafroller moths, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae) and Pandemis pyrusana (Kearfott), were evaluated for responses to a paste formulation loaded with a range of concentrations of the two species' pheromone blends and evaluated in a laboratory wind tunnel and in the field. Response criteria were flight, flight towards the pheromone source, and contact with the pheromone source for the wind tunnel assays, and capture of moths in traps for the field tests. In the wind tunnel and field, responses of males of both species to the paste generally increased as the pheromone concentration in the paste was increased. There was little response by either species to paste with less than 0.16% pheromone. The relationship between pheromone concentration and response for P. pyrusana was linear and for C. rosaceana was sinusoidal over the range of pheromone concentrations tested. These patterns were seen both in the wind tunnel and in the field. Initial release rates from the paste of (Z)-11-tetradecenyl acetate, the main component of the pheromone blends of both species was 3.6-3.8 ng/h. Inhibitory thresholds for responses were not reached for either species, using pheromone concentrations as high as 16%, in either the wind tunnel or the field. For both species, response of males to rubber septa with one mg pheromone loads was similar to the response to the paste with pheromone at concentrations greater than 3-4%. For C. rosaceana, rates of contact with the paste in the wind tunnel were statistically similar to rates of contact in response to conspecific females, with paste pheromone concentrations above 1.6%. Response rates for males of P. pyrusana were significantly lower to the paste than to conspecific females at all paste pheromone concentrations tested. Overall, the optimum pheromone concentration in the paste for moth attraction to contact was 3.2 % for C. rosaceana and 8% for P. pyrusana.

A Codling Moth (Lepidoptera: Tortricidae) Kairomonal Lure Is Marginally Effective at Decreasing Fruit Damage in Apple Trees Outside of Orchard Settings.

Codling moth, Cydia pomonella (L.), is a significant pest of pome fruits and walnuts worldwide. Recently, a three-chemical kairomonal lure, comprised of pear ester, acetic acid, and n-butyl sulfide, was successfully used as an attractant in a mass-trapping scheme to reduce fruit damage in commercial apple orchards. In this study, we tested whether this same attractant could be used outside of an orchard setting to decrease fruit damage in isolated, unmanaged apple (Malus spp.) (Rosales: Rosaceae) trees. Traps containing the lures were placed in trees before the first codling moth flight and maintained throughout the summer. We found that while the traps statistically reduced the percent of apples damaged near the trap, the effect was smaller than expected and limited to areas near the trap. It is currently unclear, but site-specific effects (e.g., host type, apple density, codling moth source) may be important factors in the efficacy of management tools in these systems. While kairomone-based trapping could be a practical and feasible management tool in individual trees outside of orchards, more work needs to be done to understand the limitations of this method.

Field Experiment of a Three-Chemical Controlled-Release Dispensers to Attract Codling Moth (Cydia pomonella) (Lepidoptera: Tortricidae).

Male and female codling moths, Cydia pomonella (Lepidoptera: Tortricidae), were shown to be attracted to a three-chemical kairomonal lure consisting of pear ester, acetic acid, and n-butyl sulfide. A controlled-release device based on sachets was developed in the laboratory and field tested to optimize the attractiveness of C. pomonella to this combination of attractants, and to decrease material costs associated with the controlled-release of these chemicals. The lure was most effective when pear ester was released from a separate dispenser than when combined acetic acid and n-butyl sulfide. We found that acetic acid and n-butyl sulfide can be combined into one device without decreasing C. pomonella trap catches and that there is minimal pear release rate before trap catch is negatively affected. A sachet-based controlled-release system of pear ester, acetic acid, n-butyl sulfide is a cost-effective alternative to a vial and septa controlled-release system and allows for easier quantification of ideal release rates. A reduction in material costs associated with management are important in promoting the adoption of attract-and-kill and mass-trapping paradigms for C. pomonella management. These findings also have important consequences in interpreting studies that use different loads of pear ester, and emphasize the need to better understand the release rates of attractants.

Associative Learning of Food Odors by the European Paper Wasp, Polistes dominula Christ (Hymenoptera: Vespidae).

We investigated associative learning of food odors by the European paper wasp Polistes dominula Christ (Hymenoptera: Vespidae) because of consistent low rates of attraction to food materials in laboratory assays. We hypothesized that wasps in nature exhibit nonspecific food-finding behavior until locating a suitable food, and then respond more strongly and specifically to odors associated with that food reward. Female P. dominula workers exhibited higher rates of attraction in a flight tunnel to piped odors of fermented fruit purees following previous experience with that puree, compared to wasps with no prior experience with the fermented fruits. Attraction behavior included upwind-oriented flight and casting within the odor plume, indicative of chemoanemotaxis. Synthetic chemicals representative of volatiles P. dominula may encounter in nature while foraging was also tested. Similar increases in attraction responses occurred following feeding experience with a sugar solution that included either 3-methyl-1-butanol or pear ester, but not eugenol. These experimental results support the hypothesis of associative learning of food odors in P. dominula. We discuss the ecological relevance of our results and suggest an alternative approach to trap paper wasps in pest situations utilizing learned chemical attractants.

Mass-Trapping Codling Moth, Cydia pomonella (Lepidopteran: Torticidae), Using a Kairomone Lure Reduces Fruit Damage in Commercial Apple Orchards.

Codling moth Cydia pomonella L. (Lepidoptera: Tortricidae) is a major pest of pome fruits worldwide. Fruit is damaged by larval feeding, and numbers of larvae are directly related to the numbers of females in the preceding generation. In Pacific Northwest, apple orchards, C. pomonella are generally managed with insecticides and mating disruption. However, additional control methods are needed when these treatments fail or are undesirable. Using a three-component kairomone lure that attracts both sexes, we mass-trapped C. pomonella in 4-acre plots located within commercial apple orchards. In all cases, there were smaller increases in fruit infestation in the mass-trapped plots than in the corresponding control plots. This relative decrease in fruit infestation in the mass-trapped plots corresponded with the removal of more male and female C. pomonella. Mass-trapping using this lure has potential to be a novel and promising addition to integrated pest management of C. pomonella.

A Multiple-Choice Bioassay Approach for Rapid Screening of Key Attractant Volatiles.

Fermentation volatiles attract a wide variety of insects and are used for integrated pest management. However, identification of the key behavior modifying chemicals has often been challenging due to the time consuming nature of thorough behavioral tests and unexpected discrepancies between laboratory and field results. Thus we report on a multiple-choice bioassay approach that may expedite the process of identifying field-worthy attractants in the laboratory. We revisited the four-component key chemical blend (acetic acid, ethanol, acetoin, and methionol) identified from 12 antennally active wine and vinegar chemicals for Drosophila suzukii (Matsumura) (Diptera: Drosophilidae). The identification of this blend took 2 yr of continuous laboratory two-choice assays and then similarly designed field trials. This delay was mainly due to a discrepancy between laboratory and field results that laboratory two-choice assay failed to identify methionol as an attractant component. Using a multiple-choice approach, we compared the co-attractiveness of the 12 potential attractants to an acetic acid plus ethanol mixture, known as the basal attractant for D. suzukii, and found similar results as the previous field trials. Only two compounds, acetoin and, importantly, methionol, increased attraction to a mixture of acetic acid and ethanol, suggesting the identification of the four-component blend could have been expedited. Interestingly, the co-attractiveness of some of the 12 individual compounds, including a key attractant, methionol, appears to change when they were tested under different background odor environments, suggesting that background odor can influence detection of potential attractants. Our findings provide a potentially useful approach to efficiently identify behaviorally bioactive fermentation chemicals.

A kairomone based attract-and-kill system effective against alfalfa looper (Lepidoptera: Noctuidae).

A chemical lure derived from flowers that are visited by moths attracts male and female alfalfa loopers, Autographa californica (Speyer) (Lepidoptera: Noctuidae). This feeding attractant is dispensed from polypropylene bottles that provide controlled release for several weeks. A killing station was tested in the laboratory, in a screenhouse, and in the field in combination with this lure as an "attract-and-kill" system. Starved alfalfa looper adults (moths) were strongly attracted to the attract-and-kill station in a flight tunnel, and 90.9% of female moths and 87.6% of male moths that contacted the station died. In commercial fields of alfalfa hay, female moths captured in monitoring traps were reduced by 80-93% in plots receiving 125 attract-and-kill stations per hectare. In screenhouse trials using two attract-and-kill stations per screenhouse, oviposition on potted lettuce plants by starved female alfalfa looper moths was reduced by 98.5%. Moths were less likely to be attracted to lures when provided sugar before flight tunnel assays, and oviposition by fed moths was much less affected by attract-and-kill stations in screenhouse trials, compared with starved moths. This method has potential as a means to manage alfalfa looper populations in vegetable and other agricultural crops. However, consideration must be given to competing food and odor sources in the field.

Effect of Chemical Ratios of a Microbial-Based Feeding Attractant on Trap Catch of Drosophila suzukii (Diptera: Drosophilidae).

Drosophila suzukii Matsumura, spotted wing drosophila, can be trapped with a feeding attractant based on wine and vinegar volatiles and consisting of acetic acid, ethanol, acetoin, and methionol. Using that four-component blend, we found that the catch of spotted wing drosophila increased with increases in the release rate of acetoin (from 0.5 mg/d to 34 mg/d) from polyethylene sachet dispensers, and with increases in the concentrations of acetic acid (from 0.25% to 4%) or ethanol (from 0.08% to 2%) when dispensed in the trap drowning solution. However, we saw no increase in spotted wing drosophila trapped with increase of the methionol release rate from 0.4 mg/d to 4.9 mg/d or from 0.19 mg/d to 0.8 mg/d, from sachets. A new formulation based on optimized amounts of these four chemicals yielded a doubling of spotted wing drosophila trapped compared to a previously reported formulation. Further field testing confirmed that the simultaneous increases in the release rate of acetoin from a dispenser and the amount of acetic acid in the trap drowning solution provided the increased spotted wing drosophila trap response to the new formulation. These findings provide a practical means to improve the power of this lure to detect and monitor D. suzukii.

Aggregation of Thaumatomyia glabra (Diptera: Chloropidae) Males on Iris spp. Flowers Releasing Methyl Anthranilate.

Aggregations of Thaumatomyia glabra (Diptera: Chloropidae) were observed on flowers of Iris pallida Lamarck (Asparagales: Iridaceae), whereas no T. glabra (Meigen) were observed on nearby Iris germanica L. flowers. Sampling of T. glabra on I. pallida flowers revealed the presence of males only. In a previous study, T. glabra males were attracted to methyl anthranilate. We found methyl anthranilate in extracts of I. pallida flowers on which T. glabra aggregated, but not in extracts of I. germanica flowers. Applying methyl anthranilate to I. germanica flowers elicited attraction of T. glabra to the flowers. This study suggests that I. pallida flowers may attract T. glabra males to aggregate because they release the known attractant, methyl anthranilate, whereas I. germanica flowers may not be attractive because they do not release methyl anthranilate.