Conditioning Native Telenomus and Trissolcus (Hymenoptera: Scelionidae) Egg Parasitoids to Recognize the Exotic Brown Marmorated Stink Bug (Heteroptera: Pentatomidae: Halyomorpha halys).

Halyomorpha halys (Stål) (Heteroptera: Pentatomidae), the brown marmorated stink bug (BMSB), is a polyphagous fruit and vegetable pest from eastern Asia and now invasive in the United States and Europe. Earlier research revealed that the main volatile from hexane egg extracts of a western North American pentatomid, Euschistus conspersus Uhler, to which two native scelionid egg parasitoids, Telenomus podisi Ashmead and Trissolcus erugatus Johnson are highly attracted, was methyl (2E,4Z)-2,4-decadienoate, the major component of the conspecific male-produced aggregation pheromone. Conversely, extracts of BMSB eggs lacked the male-produced sesquiterpenoid H. halys pheromone components but contained C16,18,20 aldehydes (hexadecanal, octadecanal, and eicosanal); both egg-surface extracts of BMSB eggs and the C16,18,20 synthetic aldehyde blend repelled the female parasitoids. The goal of the present research was to manipulate egg-surface volatiles to induce the scelionid egg parasitoids to adopt BMSB eggs as a host. Here it was demonstrated that individual females of both parasitoids could be conditioned to H. halys egg-surface aldehydes in Y-tube olfactometer experiments, and this positive memory lasted 3-4 d. Furthermore, conditioned wasps successfully parasitized fresh H. halys eggs in no choice tests, and their offspring continued to successfully parasitize fresh H. halys eggs for 2-3 more generations. Eventually, both the individual and generational memories faded. Unconditioned female parasitoids were not attracted to H. halys egg extract or the synthetic blend of egg-surface aldehydes, nor did they parasitize BMSB eggs. Theoretical and practical implications of the research are discussed in the contexts of Hopkins' host selection principle, biological control, and instinct evolution.

Preparation of Mealybugs (Hemiptera: Pseudococcidae) for Genetic Characterization and Morphological Examination.

Mealybugs (Hemiptera: Pseudococcidae) are economically significant agricultural pests on many different crops. Because of their small size and lack of easily visible characters for identification, determination of their taxonomic status is difficult and requires technical competency to prepare a slide-mounted specimen. The standard mounting technique does not allow for analysis of the genome of the specimen. Conversely, preparatory techniques for genetic analysis of mealybugs cause either loss of the entire individual or physical damage that can make morphology-based identification difficult. This study describes a simple protocol that does not impact physical integrity of the specimen for fixation and microscopic examination yet enables simultaneous DNA extraction for DNA-based identification of four mealybug species. All species prepared yielded high quality slide mounts, identified as Planococcus citri Risso, Pseudococcus viburni Signoret, Rhizoecus kondonis Kuwana, or Rhizoecus californicus Ferris. DNA extracted in this manner had higher purity and yield in the final eluate than in samples extracted using standard methods. DNA extracted was successfully amplified by polymerase chain reaction using primers for the cytochrome oxidase I gene and subsequently sequenced for all specimens. This protocol is likely to be applicable to other Hemiptera taxa that are preserved by slide mounting, allowing for both the preparation of a high-quality voucher specimen for morphological identification and simultaneous analysis of DNA for the same specimen. The methods used are technically less challenging than current standard procedures.

Using comparative genomics to develop a molecular diagnostic for the identification of an emerging pest Drosophila suzukii.

Drosophila suzukii (Spotted Wing Drosophila) has recently become a serious invasive pest of fruit crops in the USA, Canada, and Europe, leading to substantial economic losses. D. suzukii is a direct pest, ovipositing directly into ripe or ripening fruits; in contrast, other Drosophilids utilize decaying or blemished fruits and are nuisance pests at worst. Immature stages of D. suzukii are difficult to differentiate from other Drosophilids, posing problems for research and for meeting quarantine restrictions designed to prevent the spread of this pest in fruit exports. Here we used a combined phylogenetic and bioinformatic approach to discover genetic markers suitable for a species diagnostic protocol of this agricultural pest. We describe a molecular diagnostic for rapid identification of single D. suzukii larva using multiplex polymerase chain reaction. Our molecular diagnostic was validated using nine different species of Drosophila for specificity and 19 populations of D. suzukii from different geographical regions to ensure utility within species.

Seasonal monitoring for Drosophila suzukii (Diptera: Drosophilidae) in California commercial raspberries.

Native to Southeast Asia, Drosophila suzukii (Matsumura) prefer to oviposit on ripe fruit and have become an important pest of California raspberries (Rubus idaeus L.) since their detection in Santa Cruz County, CA, in 2008. Preliminary management guidelines included D. suzukii monitoring recommendations, though there was little available information on seasonal occurrence and potential lures for use in raspberries. To address this issue, we trapped adult D. suzukii weekly for 2 yr (including both spring and fall harvests) in multiple raspberry varieties using apple cider vinegar and a yeast-sugar-water mixture as liquid lures, and measured fruit infestation when commercially ripe fruit were available. D. suzukii pressure as measured by larval infestation and adult trap captures was higher during the fall raspberry harvest season. The yeast lure captured significantly more D. suzukii during the fall harvest than the apple cider vinegar, and while both lures tended to capture more females than males, this varied by month of the year and was more pronounced for the yeast lure. Trap captures from each lure correlated well to one another, and often exhibited significant correlation to larval infestation. However, during all seasons and under both conventional and organic management, worrisome outliers were present (high larval infestation with low trap captures) that call into question the reliability of using the systems presented here as a basis for management decisions at this time.

Host status and fruit odor response of Drosophila suzukii (Diptera: Drosophilidae) to figs and mulberries.

Drosophila suzukii Matsumura (Diptera: Drosophilidae) is an agricultural pest with a wide host range. It is known to infest fruit that are still ripening on the plant, as well as rotting and damaged fruit. Our study sought to determine whether D. suzukii use mulberries (Morus spp.) and figs (Ficus carica (L.)) as hosts, as their host status was ambiguous. Accordingly, we collected 25 field-infested fruit and counted the numbers of D. suzukii emerging from them. We also sought to determine whether female D. suzukii would respond to olfactory cues from ripe figs and mulberries. As the host population has been known to impact host odor response, flies from mulberry, fig, and cherry origins were tested in "one-choice" olfactometry studies. Our results show that mulberries and figs can serve as hosts for D. suzukii and that female flies will respond to their odors. The host population did affect response to fruit odors, although further studies are necessary to determine habitat fidelity. This has implications for management of this pest, especially in backyard and mixed fruit orchard situations, which commonly occur in the current range of D. suzukii, and fig and mulberry may serve as a pest reservoir for other hosts and cultivated crops.

Laboratory studies of Blattisocius keegani (Fox) (Acari: Ascidae) reared on eggs of navel orangeworm: potential for biological control.

Blattisocius keegani (Fox) is a predatory mite in the family Ascidae (Acari), noted for potential biological control of Coleopteran stored product pests. Performance of B. keegani on eggs of navel orangeworm, Amyelois transitella Walker (Lepidoptera: Pyralidae), was investigated. Mites completed development from egg to adult in 9.2±0.22 days at 25°C and 50-60% relative humidity, and in 6.33±0.29 days at 32.2°C, 30% relative humidity. Mites provisioned with three or five eggs consumed a median of 1.25 to 1.5 eggs, with a maximum of three eggs consumed over 24 h. Regression analyses indicated egg-laying by B. keegani was significantly correlated with the number of A. transitella eggs consumed, and female mites laid an average of 5.82±0.44 eggs over 72 h. Blattisocius keegani, developed on fresh and frozen eggs, laid significantly more eggs when provided with fresh eggs (F3,26=6.16, P=0.0026) and were able to develop on frozen Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs as an alternative host. Mites were equally fecund when fed eggs stored at 0° or -20°C. Provisioning of adult moth bodies in addition to egg prey items increased mite fecundity, although it was demonstrated that B. keegani are phoretic on adult moths as well. The results are the first experimental evidence of B. keegani as a predator of Lepidopteran eggs, as a phoretic species, and of their potential for biological control of navel orangeworm.

Analysis of olive fly invasion in California based on microsatellite markers.

The olive fruit fly, Bactrocera oleae, is the main pest of the olive fruit and its expansion is exclusively restricted to the cultivation zone of the olive tree. Even though olive production has a century-old history in California, the olive fly was first detected in the Los Angeles area in 1998. Within 5 years of the first observation, the insect was reported from all olive cultivation areas of the state. Field-collected flies from five locations in California and another from Israel were analyzed on the basis of microsatellite polymorphisms in 10 microsatellite loci. These results were integrated with those of a previous study of olive fly populations around the European part of the Mediterranean basin. The analysis pointed to the eastern part of the Mediterranean as the putative source of the observed invasion. Moreover, samples from California were quite different from Mediterranean samples implying the participation of phenomena such as genetic drift during the invasion and expansion of the olive fly in California.

Unusual pheromone chemistry in the navel orangeworm: novel sex attractants and a behavioral antagonist.

Using molecular- and sensory physiology-based approaches, three novel natural products, a simple ester, and a behavioral antagonist have been identified from the pheromone gland of the navel orangeworm, Amyelois transitella Walker (Lepidoptera: Pyralidae). In addition to the previously identified (Z,Z)-11,13-hexadecadienal, the pheromone blend is composed of (Z,Z,Z,Z,Z)-3,6,9,12,15-tricosapentaene, (Z,Z,Z,Z,Z)-3,6,9,12,15-pentacosapentaene, ethyl palmitate, ethyl-(Z,Z)-11,13-hexadecadienoate, and (Z,Z)-11,13-hexadecadien-1-yl acetate. The C(23) and C(25) pentaenes are not only novel sex pheromones, but also new natural products. In field tests, catches of A. transitella males in traps baited with the full mixture of pheromones were as high as those in traps with virgin females, whereas control and traps baited only with the previously known constituent did not capture any moths at all. The navel orangeworm sex pheromone is also an attractant for the meal moth, Pyralis farinalis L. (Pyralidae), but (Z,Z)-11,13-hexadecadien-1-yl acetate is a behavioral antagonist. The new pheromone blend may be highly effective in mating disruption and monitoring programs.

Sex attractant pheromone of the red-shouldered stink bug Thyanta pallidovirens: a pheromone blend with multiple redundant components.

The male-produced sex pheromone of the red-shouldered stink bug, Thyanta pallidovirens (Stål) (Hemiptera: Pentatomidae) consists of a blend of methyl (E2,Z4,Z6)-decatrienoate (E2,Z4,Z6-10:COOMe), and the sesquiterpenes (+)-alpha-curcumene, (-)-zingiberene, and (-)-beta-sesquiphellandrene. In laboratory bioassays, sexually mature males attracted sexually mature females but not males, and females did not attract either sex. Extracts of volatiles collected from sexually mature males contained compounds not present in extracts from females or sexually immature males, and male-produced extract was attractive to females. Biological activity was lost when the extract was fractionated, indicating that the pheromone consisted of at least two components having different chemical properties. Individually, pheromone components were not attractive to females, but E2,Z4,Z6-10:COOMe in combination with at least one of the three male-produced sesquiterpenes was attractive. The presence of more than one sesquiterpene in the blend did not increase attraction, indicating redundancy in the pheromone signal. Male extract was as attractive as a blend reconstructed from synthesized compounds, indicating all biologically active components had been identified. In bioassays conducted at dusk in a 1- x 1- x 1-m screen field cage, females were attracted to synthetic pheromone lures. In field trials, adult female T pallidovirens were attracted to pheromone-baited traps in relatively low numbers. The profile of volatiles released by sexually mature males of a congeneric species, Thyanta accerra custator McAtee, was remarkably similar to that of male T. pallidovirens, with the exception that the former species produced (E)-2-decenal, a compound that was not found in T. pallidovirens extracts.