Blair J. Sampson

A four-component synthetic attractant for Drosophila suzukii (Diptera: Drosophilidae) isolated from fermented bait headspace

BACKGROUND A mixture of wine and vinegar is more attractive than wine or vinegar to spotted wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), and ethanol and acetic acid are considered key to that attractiveness. In addition to ethanol and acetic acid, 13 other wine and vinegar volatiles are antennally active to D. suzukii and might be involved in food finding. RESULTS Out of the 13 antennally active chemicals, acetoin, ethyl lactate and methionol increased fly response to a mixture of acetic acid and ethanol in field trapping experiments. A five-component blend of acetic acid, ethanol, acetoin, ethyl lactate and methionol was as attractive as the starting mixture of wine and vinegar in field tests conducted in the states of Oregon and Mississippi. Subtracting ethyl lactate from the five-component blend did not reduce the captures of flies in the trap. However, subtracting any other compound from the blend significantly reduced the numbers of flies captured. CONCLUSION These results indicate that acetic acid, ethanol, acetoin and methionol are key olfactory cues for D. suzukii when attracted to wine and vinegar, which may be food-finding behavior leading flies to fermenting fruit in nature. It is anticipated that this four-component blend can be used as a highly attractive chemical lure for detection and management of D. suzukii. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Pollination efficiencies of three bee (Hymenoptera: Apoidea) species visiting rabbiteye blueberry

Abstract Inadequate bee pollination limits rabbiteye blueberry,Vaccinium ashei Reade, production in the some areas of thesoutheastern United States. Honey bees, Apis mellifera L.,are currently the only manageable pollinators available for pollinatingV. ashei. However, a new adaptable pollinator for rabbiteyeblueberry, Osmia ribifloris Cockerell, was successfullyreared and flown in captivity. The bee nested successfully in woodenshelters and conferred superior fruit set to 2-yr-old potted, rabbiteyeblueberry bushes. Pollination efficiency or the percentage of blueberryflowers to set fruit after being visited once by a female O.ribifloris was comparable to that of the female blueberry beeHabropoda laboriosa (F.) and worker honey bees.Interestingly, honey bees once thought to be inefficient pollinators ofrabbiteye blueberry were found to be very efficient, especially for‘Climax’ and ‘Premier’ flowers.

Nectar Robbery by Bees Xylocopa virginica and Apis mellifera Contributes to the Pollination of Rabbiteye Blueberry

Abstract Honey bees, Apis mellifera L., probe for nectar from robbery slits previously made by male carpenter bees, Xylocopa virginica (L.), at the flowers of rabbiteye blueberry, Vaccinium ashei Reade. This relationship between primary nectar robbers (carpenter bees) and secondary nectar thieves (honey bees) is poorly understood but seemingly unfavorable for V. ashei pollination. We designed two studies to measure the impact of nectar robbers on V. ashei pollination. First, counting the amount of pollen on stigmas (stigmatic pollen loading) showed that nectar robbers delivered fewer blueberry tetrads per stigma after single floral visits than did our benchmark pollinator, the southeastern blueberry bee, Habropoda laboriosa (F.), a recognized effective pollinator of blueberries. Increasing numbers of floral visits by carpenter bee and honey bee robbers yielded larger stigmatic loads. As few as three robbery visits were equivalent to one legitimate visit by a pollen-collecting H. laboriosa female. More than three robbery visits per flower slightly depressed stigmatic pollen loads. In our second study, a survey of 10 commercial blueberry farms demonstrated that corolla slitting by carpenter bees (i.e., robbery) has no appreciable affect on overall V. ashei fruit set. Our observations demonstrate male carpenter bees are benign or even potentially beneficial floral visitors of V. ashei. Their robbery of blueberry flowers in the southeast may attract more honey bee pollinators to the crop.

Biology of Parasitoids (Hymenoptera) Attacking Dasineura oxycoccana and Prodiplosis vaccinii (Diptera: Cecidomyiidae) in Cultivated Blueberries

Abstract The blueberry gall midge, Dasineura oxycoccana (Johnson), and blueberry tip midge, Prodiplosis vaccinii (Felt) (Diptera: Cecidomyiidae), are recurring cecidomyiid pests of cultivated blueberries in the southern United States and Mediterranean Europe. Insecticides can give short-term control, but overlap in parasitoid phenologies indicates the potential for natural control of midge populations. Using a combination of laboratory rearing and mitochondrial DNA analysis of field samples, we identified five species of solitary endoparasitoids that killed 30–40% of midges. These species include at least three undescribed platygastrids in the genera Synopeas, Platygaster, and Inostemma. An undescribed prepupal idiobiont, Aprostocetus sp. (Eulophidae: Tetrastichinae) was the only midge parasitoid that was consistently active when rabbiteye blueberries, Vaccinium ashei Reade, were in flower. Six percent of midge prepupae, half of which already contained platygastrid larvae, were parasitized by Aprostocetus.

Polistes spp. (Hymenoptera: Vespidae) orientation to wine and vinegar

Abstract Attractants are sought for trapping of Polistes spp. paper wasps when they are pestiferous. The serendipitous capture of Polistes metricus Say and Polistes bellicosus Cresson in traps baited with a wine/vinegar mixture for spotted wing drosophila, Drosophila suzukii (Matsumura) prompted experiments to determine the nature of the wasp response. Both wasp species were captured in subsequent field tests in traps baited with the same mixture of wine plus vinegar, and not in unbaited traps. Polistes bellicosus responses to wine, vinegar, ethanol (as a major volatile of wine), and acetic acid (as a major volatile of vinegar) were evaluated using a Y-tube olfactometer. In the olfactometer, P. bellicosus wasps were attracted to wine and not to vinegar. They also preferred wine alone to wine with vinegar, and were attracted to ethanol. Female wasps were deterred by acetic acid. In field tests comparing traps baited with wine, vinegar and a combination of the 2 materials, P. bellicosus and Polistes fuscatus (Fab.) were captured in traps baited with wine, but were not trapped with vinegar. The inclusion of vinegar with wine did not improve bait attractiveness in the field. We conclude that the paper wasp response to the D. suzukii bait of wine plus vinegar was largely the result of the wasp response to wine. This work constitutes the first demonstration of an attractive bait that can be used to trap P. bellicosus and P. metricus in situations where they are pestiferous, and suggests a potential source of a chemical attractant based on wine volatiles.

Effects of Kaolin Clay Application on Flower Bud Development, Fruit Quality and Yield, and Flower Thrips [Frankliniella spp. (Thysanoptera: Thripidae)] Populations of Blueberry Plants

Abstract Three separate studies were conducted to report the effects of kaolin applications (Surround WP) on southern highbush blueberries (Vaccinium corymbosum L.) and rabbiteye (V. ashei Reade) blueberries. When applied to mature blueberry plants, kaolin clay emulsion dried to form a white reflective film that affected bud development, fruit set and development, plant growth, and fruit yield, but had no effect on fruit quality parameters. When kaolin was applied before fruit set, yield was increased with no significant residue left on the fruit. Surround WP consistently reduced the number of flower thrips (Frankliniella spp.) within the canopy of rabbiteye blueberry plants by approximately 50%. Kaolin applications were not phytotoxic to blueberry buds, flowers, leaves, or fruit and were harmless to foraging bees.

Ingestible insecticides for spotted wing Drosophila control: a polyol, Erythritol, and an insect growth regulator, Lufenuron

Bioassays tested insecticidal activity of Erythritol from the nutritive sweetener, Truvia, and an insect growth regulator, Lufenuron, against life stages (eggs, larvae, pupae, adults) of Drosophila melanogaster (Meigen) and Drosophila suzukii (Matsumura), the spotted wing Drosophila (SWD). These compounds were chosen for their demonstrated acute toxicity to adult and larval Drosophila and potential use on organic fruit farms. D. melanogaster fed on standard Drosophila diet media moistened with water containing known concentrations of Erythritol. Likewise, SWD consumed standard diet media as well as thawed host fruit (blackberries and blueberries) treated with solutions of Erythritol, Lufenuron or both. During the first bioassay, Erythritol at lower concentrations between 0 and 500 mm (~61 000 ppm) in water and mixed with instant diet media increased adult survival from ~80% to 97% for D. melanogaster and SWD. However, from aqueous concentrations ranging from 1750 (~414 000 ppm) to 2000 mm (~244 000 ppm), Erythritol killed 100% of adult Drosophila in culture vials. One hundred per cent mortality for SWD and D. melanogaster occurred at ≥0.5 m (~61 000 ppm) Erythritol added to diet media or topically applied to host fruit. In a second bioassay, 0.013–1.000 ppm of aqueous Lufenuron, a chitin synthase inhibitor, when added to dry diet media prevented 90–99% of SWD from reaching the pupal stage. In another assay, ~67% of SWD eggs or neonates (early first instars) died inside blackberries pre‐treated with (dipped in) a soapy solution of 10 ppm Lufenuron. Pre‐treating blackberry fruit with an Erythritol–Lufenuron mixture reduced SWD brood survival by 99%. Likewise, during our last fruit‐based bioassay, 98% of eggs and neonates died inside blueberries similarly pre‐treated. During the last experiment, Lufenuron in diet media also rendered adult females sterile. Sterility, however, dissipated over 7 days once females began feeding on a Lufenuron‐free diet media.

Molecular and Phytochemical Investigation of Angelica dahurica and Angelica pubescentis Essential Oils and Their Biological Activity against Aedes aegypti, Stephanitis pyrioides, and Colletotrichum Species

In this study, Angelica dahurica and Angelica pubescentis root essential oils were investigated as pest management perspectives, and root samples were also analyzed genetically using the nuclear ribosomal internal transcribed spacer (ITS) region as a DNA barcode marker. A. pubescentis root essential oil demonstrated weak antifungal activity against Colletotrichum acutatum, Colletotrichum fragariae, and Colletotrichum gloeosporioides, whereas A. dahurica root essential oil did not show antifungal activity. Conversely, A. dahurica root essential oil demonstrated better biting deterrent and insecticidal activity against yellow fever mosquito, Aedes aegypti, and azalea lace bugs, Stephanitis pyrioides, than A. pubescentis root oil. The major compounds in the A. dahurica oil were found as α-pinene (46.3%), sabinene (9.3%), myrcene (5.5%), 1-dodecanol (5.2%), and terpinen-4-ol (4.9%). α-Pinene (37.6%), p-cymene (11.6%), limonene (8.7%), and cryptone (6.7%) were the major compounds found in the A. pubescentis oil. In mosquito bioassays, 1-dodecanol and 1-tridecanol showed antibiting deterrent activity similar to the positive control DEET (N,N-diethyl-3-methylbenzamide) at 25 nmol/cm(2) against Ae. aegypti, whereas only 1-tridecanol showed repellent activity in human-based cloth patch bioassay with minimum effective dosages (MED) of 0.086 ± 0.089 mg/cm(2) (DEET = 0.007 ± 0.003 mg/cm(2)). In larval bioassays, 1-tridecanol was more toxic with an LC50 value of 2.1 ppm than 1-dodecanol having an LC50 value of 5.2 ppm against 1-day-old Ae. aegypti larvae. 1-Dodecanol and 1-tridecanol could be useful for the natural mosquito control agents.

Erythritol and Lufenuron Detrimentally Alter Age Structure of Wild Drosophila suzukii (Diptera: Drosophilidae) Populations in Blueberry and Blackberry

Abstract We report on the efficacy of 0.5 M (61,000 ppm) erythritol (E) in Truvia Baking Blend, 10 ppm lufenuron (L), and their combination (LE) to reduce egg and larval densities of wild populations of Drosophila suzukii (Matsumura) infesting fields of rabbiteye blueberries (Vaccinium virgatum) and blackberries (Rubus sp.). Formulations included the active ingredients (lufenuron, erythritol, or both), sugar (in control and erythritol treatments), and Dawn hand-soap applied to plants with pressurized 3-gallon garden spray tanks. The three chemical treatments (E, L, and LE) had no effect on D. suzukii ovipositing in blackberry and blueberry fruit, but they did reduce larval infestation by 75%, particularly densities of first and second instars. Erythritol and lufenuron were equally efficacious compounds as a D. suzukii ovicide and larvicide, but they did not display additive or synergistic activity. Extremely high larval mortality in control fruits show an age structure heavily skewed toward egg output.

Seasonal and spatial dispersal patterns of select ambrosia beetles (Coleoptera: Curculionidae) from forest habitats into production nurseries

Abstract Exotic ambrosia beetles (Coleoptera: Curculionidae) are important pests of ornamental tree nurseries. Although these beetles reportedly disperse in early spring from peripheral forested areas into nurseries, few studies have determined how far they fly to infest new host trees, or whether a masstrapping strategy can adequately protect a nursery crop. Field monitoring with ethanol baits in South Carolina (2011–2012), Mississippi (2013–2014), and Louisiana (2013–2014), USA, determined the timing of peak ambrosia beetle flights, dispersal distance, and optimal trap location. In addition to the well-documented spring flight peak, southeastern nursery managers may need to be aware of a second, late-summer flight. Captures from traps placed in a nursery at various distances (−25 to 200 m) from the forest—nursery interface showed a significant linear and quadratic trend in decreasing numbers of beetles captured with increasing distance from the forest in South Carolina, whereas significant linear, quadratic, and cubic trends were detected in Louisiana and Mississippi. Although captures at the nursery edge were lower than within the forest, traps placed at the nursery edge may still represent the optimal tool for both monitoring and mass-trapping programs because of easier access for personnel. Susceptible tree cultivars may gain added protection when placed deeper within nursery interiors and when baited traps line adjacent nursery edges.