Evaluating global Vaccinium germplasm for resistance against invasive Drosophila suzukii (Diptera: Drosophilidae).

Control of spotted-wing Drosophila, Drosophila suzukii, in small fruits emphasizes biological, cultural, and chemical approaches, whereas studies of host plant resistance as a form of genetic control are just getting underway. The identification of resistance patterns among genotypes of host plants whose fruit, leaves, roots, stems, or seeds are specifically targeted by an invasive pest is the first step in the development of an effective genetic control. Therefore, a detached fruit bioassay was developed to screen for D. suzukii oviposition and larval infestation within berries from 25 representative species and hybrids of wild and cultivated Vaccinium. Ten Vaccinium species showed strong resistance; among them, two wild diploids originating from within the fly's native range: V. myrtoides and V. bracteatum. Other resistant species came from the sections Pyxothamnus and Conchophyllum. They included New World V. consanguineum and V. floribundum. Large-cluster blueberry, V. amoenum, and three Floridian genotypes of related rabbiteye blueberry, V. virgatum, were the only hexaploids expressing strong resistance against D. suzukii. Most screened blueberry genotypes from managed lowbush and cultivated highbush types were susceptible to the flies' attacks (i.e., oviposition). Tetraploid blueberries tended to host the most eggs, whereas diploids and hexaploids harbored 50%-60% fewer eggs, on average. D. suzukii cannot lay eggs or complete development in the smallest, sweetest, and firmest diploid fruits. Likewise, certain genotypes of large-fruited tetraploid and hexaploid blueberry strongly curbed D. suzukii egg-laying and larval growth, indicating the possibility of heritable resistance operating against this invasive fly species.

Sensitivity to imidacloprid insecticide varies among some social and solitary bee species of agricultural value.

Pollinator health risks from long-lasting neonicotinoid insecticides like imidacloprid has primarily focused on commercially managed, cavity-nesting bees in the genera Apis, Bombus, and Osmia. We expand these assessments to include 12 species of native and non-native crop pollinators of differing levels of body size, sociality, and floral specialization. Bees were collected throughout 2016 and 2017 from flowering blueberry, squash, pumpkin, sunflower and okra in south Mississippi, USA. Within 30-60 minutes of capture, bees were installed in bioassay cages made from transparent plastic cups and dark amber jars. Bees were fed via dental wicks saturated with 27% (1.25 M) sugar syrup containing a realistic range of sublethal concentrations of imidacloprid (0, 5, 20, or 100 ppb) that are often found in nectar. Bees displayed no visible tremors or convulsions except for a small sweat bee, Halictus ligatus, and only at 100ppb syrup. Imidacloprid shortened the captive longevities of the solitary bees. Tolerant bee species lived ~10 to 12 days in the bioassays and included two social and one solitary species: Halictus ligatus, Apis mellifera and Ptilothrix bombiformis (rose mallow bees), respectively. No other bee species tolerated imidacloprid as well as honey bees did, which exhibited no appreciable mortality and only modest paralysis across concentration. In contrast, native bees either lived shorter lives, experienced longer paralysis, or endured both. Overall, longevity decreased with concentration linearly for social bees and non-linearly for solitary species. The percentage of a bee's captive lifespan spent paralyzed increased logarithmically with concentration for all species, although bumble bees suffered longest. Of greatest concern was comparable debilitation of agriculturally valuable solitary bees at both low and high sublethal rates of imidacloprid.

Association Between Density of Foraging Bees and Fruit Set in Commercial Fields of Rabbiteye Blueberries (Ericales: Ericaceae) in Louisiana and Mississippi.

Field-scale data on the relationship between pollinator activity and fruit set are scarce for rabbiteye blueberries (Vaccinium virgatum Aiton). We measured the densities of Apis mellifera L. (Hymenoptera: Apidae), Habropoda laboriosa F. (Hymenoptera: Apidae), Bombus Latreille (Hymenoptera: Apidae) spp., and Xylocopa virginica L. (Hymenoptera: Apidae) in 7-21 commercial fields during each of 3 yr in Louisiana and Mississippi. Foraging bees were counted on 10 'Tifblue' bushes per field on 2 d during bloom, and the density of bees per flower was calculated based on the number of flowers open during the counts. Fruit set was measured 30 d after bloom. The impact of foraging activity on fruit set was inconsistent when densities of either all foragers or foragers of individual taxa were considered. Strong associations were observed only in 2001, with fruit set increased by H. laboriosa and Bombus and with a weaker contribution by A. mellifera. Floral robbery by X. virginica had no measurable negative effects. Populations of H. laboriosa were more consistent than those of other bees across sites. Managed colonies of A. mellifera were added at two densities (12.5 or 2.5 colonies per hectare) in seven fields each in 2001. These supplemental bees did not result in greater forager densities or fruit set in stocked fields. The observations show the challenge of field-scale pollination tests but provide an initial framework for rabbiteye blueberry growers to assess the availability of foraging bees early in bloom to help decide whether to add supplemental A. mellifera to try to enhance pollination if populations of non-Apis bees are low.

Laboratory and Field Assessments of Erythritol Derivatives on the Survival, Reproductive Rate, and Control of Drosophila suzukii (Diptera: Drosophilidae).

Spotted-wing Drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is a vinegar fly introduced unintentionally into the United States. Since 2008, D. suzukii has reduced annual berry yields from 6 to 100%. Effective control of D. suzukii during harvest requires weekly applications of low-residual, broad-spectrum insecticides that are unavailable for organic farming. A novel ingestible insecticide, a 4-carbon polyol, mesoerythritol (erythritol), was found to kill 75 to 100% of larval and adult D. suzukii. However, mesoerythritol, at effective concentrations (0.5-1.0M), may be cost-prohibitive. Therefore, we conducted laboratory tests to assess the effects of lower cost derivatives of erythritol, namely the pentaerythritol series of 1,3-diols on D. suzukii pupal production, adult production, adult mortality, brood output, and reproductive increase. We then selected the two most promising compounds for a field test on fruiting rabbiteye blueberry. From 90 to 100% of adults died when fed food moistened with 1M solutions of mesoerythritol and pentaerythritol. Mesoerythritol and dipentaerythritol at a concentration of 1M were ovicidal/larvicidal, killing ≥85% of immatures. Overall, 1M mesoerythritol killed 80% or more larvae and adults, thus bringing populations to near zero. The heaviest compound of this series, tripentaerythritol, at all concentrations, was largely benign to both adults and immatures. Thus, we cannot recommend tripentaerythritol for D. suzukii control. In a blueberry field, 0.5M mesoerythritol and 0.5M pentaerythritol, each by themselves, reduced egg infestation by 64% and larval infestation by 93%; their combination (0.25M mesoerythritol and 0.25M pentaerythritol) achieved even greater egg control with 82% fewer eggs infesting blueberry fruits.

Effects of coumaphos and imidacloprid on honey bee (Hymenoptera: Apidae) lifespan and antioxidant gene regulations in laboratory experiments.

The main objective of this study was to test comparatively the effects of two common insecticides on honey bee Apis mellifera worker's lifespan, food consumption, mortality, and expression of antioxidant genes. Newly emerged worker bees were exposed to organophosphate insecticide coumaphos, a neonicotinoid imidacloprid, and their mixtures. Toxicity tests were conducted along with bee midgut immunohistological TUNEL analyses. RT-qPCR assessed the regulation of 10 bee antioxidant genes linked to pesticide toxicity. We tested coumaphos at 92,600 ppb concentration, in combination with 5 and 20 ppb imidacloprid. Coumaphos induced significantly higher bee mortality, which was associated with down regulation of catalase compared to coumaphos and imidacloprid (5/20 ppb) mixtures, whereas, both imidacloprid concentrations independently had no effect on bee mortality. Mixture of coumaphos and imidacloprid reduced daily bee consumption of a control food patty to 10 mg from a coumaphos intake of 14.3 mg and 18.4 and 13.7 mg for imidacloprid (5 and 20) ppb, respectively. While coumaphos and imidacloprid mixtures induced down-regulation of antioxidant genes with noticeable midgut tissue damage, imidacloprid induced intensive gene up-regulations with less midgut apoptosis.

Toxicity of Selected Acaricides to Honey Bees (Apis mellifera) and Varroa (Varroa destructor Anderson and Trueman) and Their Use in Controlling Varroa within Honey Bee Colonies.

The efficacies of various acaricides in order to control a parasitic mite, the Varroa mite, Varroa destructor, of honey bees, were measured in two different settings, namely, in laboratory caged honey bees and in queen-right honey bee colonies. The Varroa infestation levels before, during, and after the acaricide treatments were determined in two ways, namely: (1) using the sugar shake protocol to count mites on bees and (2) directly counting the dead mites on the hive bottom inserts. The acaricides that were evaluated were coumaphos, tau-fluvalinate, amitraz, thymol, and natural plant compounds (hop acids), which were the active ingredients. The acaricide efficacies in the colonies were evaluated in conjunction with the final coumaphos applications. All of the tested acaricides significantly increased the overall Varroa mortality in the laboratory experiment. Their highest efficiencies were recorded at 6 h post-treatment, except for coumaphos and thymol, which exhibited longer and more consistent activity. In the honey bee colonies, a higher Varroa mortality was recorded in all of the treatments, compared with the natural Varroa mortality during the pretreatment period. The acaricide toxicity to the Varroa mites was consistent in both the caged adult honey bees and workers in the queen-right colonies, although, two of these acaricides, coumaphos at the highest doses and hop acids, were comparatively more toxic to the worker bees.

The Giant Resin Bee, Megachile sculpturalis Smith: New Distributional Records for the Mid- and Gulf-south USA.

BACKGROUND: Megachile (Callomegachile) sculpturalis Smith, the giant resin bee, is an adventive species in the United States. First established in the United States during the early 1990s, records currently exist from most states east of the Mississippi River along with Iowa and Kansas. NEW INFORMATION: New distributional records are presented for Megachile (Callomegachile) sculpturalis Smith, an introduced bee. Additional records presented here expand the known distribution southwest through Arkansas, Louisiana, Mississippi, Missouri, and Texas. An updated host plant list containing new records is also presented, expanding the number of known floral associations.

Movement of Xylosandrus germanus (Coleoptera: Curculionidae) in Ornamental Nurseries and Surrounding Habitats.

Some exotic ambrosia beetles are damaging pests in ornamental nurseries. Xylosandrus germanus (Blandford) is the most problematic ambrosia beetle in Ohio nurseries. Movement of X. germanus in nurseries has not been characterized, and knowledge is lacking on whether infestations originate from within nurseries or surrounding habitats. Flight activity of X. germanus was monitored in nurseries and adjacent wooded areas to determine the source of beetles infesting nurseries, and characterize their movement within nurseries. Ethanol-baited bottle traps were positioned within wooded areas adjacent to commercial nurseries and within nurseries at various distances from the nursery woodlot interface. Flight activity of overwintered X. germanus occurred in wooded areas adjacent to nurseries before occurrence within nurseries. There was a direct relationship between degree-days and the distance from woodlots when X. germanus were first found in traps in spring, with earlier captures closest to wooded areas and latest ones furthest away into the nursery. X. germanus appeared to move into nurseries from adjacent wooded areas, with numbers trapped within nurseries decreasing with distance away from wooded areas. Trees in the interior of nurseries would appear to be subjected to less attack pressure than trees near the nursery border. Intercepting beetles as they move into nurseries might be an effective strategy to reduce attack pressure on valuable trees.

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.

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.

Chemical composition, antifungal and insecticidal activities of Hedychium essential oils.

The antimicrobial properties of essential oils have been documented, and their use as "biocides" is gaining popularity. The aims of this study were to analyze the chemical composition and assess the biological activities of Hedychium essential oils. Oils from 19 Hedychium species and cultivars were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) techniques. The antifungal and insecticidal activities of these oils were tested against Colletotrichum acutatum, C. fragariae, and C. gloeosporioides, and three insects, the azalea lace bug (Stephanitis pyrioides), the yellow fever mosquito (Aedes aegypti), and the red imported fire ant (Solenopsis invicta). Hedychium oils were rich in monoterpenes and sesquiterpenes, especially 1,8-cineole (0.1%-42%), linalool (<0.1%-56%), a-pinene (3%-17%), b-pinene (4%-31%), and (E)-nerolidol (0.1%-20%). Hedychium oils had no antifungal effect on C. gloeosporioides, C. fragariae, and C. acutatum, but most Hedychium oils effectively killed azalea lace bugs. The oils also show promise as an adult mosquito repellent, but they would make rather poor larvicides or adulticides for mosquito control. Hedychium oils acted either as a fire ant repellent or attractant, depending on plant genotype and oil concentration.

Biology and efficacy of Aprostocetus (Eulophidae: Hymenoptera) as a parasitoid of the blueberry gall midge complex: Dasineura oxycoccana and Prodiplosis vaccinii (Diptera: Cecidomyiidae).

In the southeastern United States, bud-infesting larvae of two gall midge species, Dasineura oxycoccana (Johnson) and Prodiplosis vaccinii (Felt), destroy from 20 to 80% of the rabbiteye blueberry crop, Vaccinium virgatum Aiton (syn. V. ashei Reade). These midge larvae are attacked by five species of parasitoid wasps. The most effective of these is the bivoltine eulophid Aprostocetus sp. nr. marylandensis (Eulophidae), whose adults constitute one-third of the gall midge parasitoids, active in both conventional and organic blueberry fields. Broods of Aprostocetus use several reproductive strategies to keep sole possession of their larval hosts. As solitary endoparasitoids as well as facultative hyperparasitoids, precocial larvae of Aprostocetus devour hosts organs along with any younger siblings and rival parasitoid broods. Although larger hosts are preferred, any sized larvae can be parasitized, which reduces brood congestion and infanticide. An Aprostocetus female spends an hour or more in a systematic hunt for hosts, during which time 40 to 100% of midge larvae encountered are parasitized. Aprostocetus females could have located hosts more quickly had they recognized host-feeding scars as cues. Even so, high rates of larval parasitism achieved by Aprostocetus may kill as many midges as insecticides do.

Insecticidal and biting deterrent activity of rose-scented geranium (Pelargonium spp.) essential oils and individual compounds against Stephanitis pyrioides and Aedes aegypti.

BACKGROUND: Rose-scented geranium, Pelargonium spp., essential oils from the cultivars 'Bourbon', 'China', 'Egypt', 'Rober's Lemon Rose' and 'Frensham' were analyzed by GC-FID and GC-MS. A total of 136 compounds were identified from five essential oils, constituting 85.5-99.7% of the oils. Essential oils and pure compounds were evaluated for their insecticidal activity against Stephanitis pyrioides and larvicidal and biting deterrent activity against Aedes aegypti. RESULTS: All five geranium oils were toxic to S. pyrioides, and four of these five were more potent than malathion and neem. Trans-nerolidol (LD50 = 13.4 ppm) was the most toxic compound against one-day-old Ae. aegypti larvae, followed by geraniol (49.3 ppm), citronellol (49.9 ppm) and geranyl formate (58.5 ppm). Essential oil of cultivar 'Egypt' at 100 µg cm(-2) [biting deterrent index (BDI) = 0.8] showed the highest biting deterrent activity, followed by cultivars 'Frensham' (BDI = 0.76), 'China' (BDI = 0.72), 'Rober's Lemon Rose' (BDI = 0.63) and 'Bourbon' (BDI = 0.45) essential oils. Among the pure compounds, the biting deterrent activity of geranic acid (BDI = 0.99) was not significantly different from that of N,N-diethyl-m-toluamide (DEET). CONCLUSION: Essential oils and pure compounds showed insecticidal activity against S. pyrioides and Ae. aegypti. The high biting deterrent activity of geranic acid points to the need for further research.

Pollination value of male bees: the specialist bee Peponapis pruinosa (Apidae) at summer squash (Cucurbita pepo).

Male bees can be abundant at flowers, particularly floral hosts of those bee species whose females are taxonomic pollen specialists (oligolecty). Contributions of male bees to host pollination are rarely studied directly despite their prevalence in a number of pollination guilds, including those of some crop plants. In this study, males of the oligolectic bee, Peponapis pruinosa Say, were shown to be effective pollinators of summer squash, Cucurbita pepo L. Seven sequential visits from male P. pruinosa maximized squash fruit set and growth. This number of male visits accumulated during the first hour of their foraging and mate searching at flowers soon after sunrise. Pollination efficacy of male P. pruinosa and their abundances at squash flowers were sufficient to account for most summer squash production at our study sites, and by extrapolation, to two-thirds of all 87 North American farms and market gardens growing squashes that were surveyed for pollinators by collaborators in the Squash Pollinators of the Americas Survey. We posit that the substantial pollination value of male Peponapis bees is a consequence of their species' oligolecty, their mate seeking strategy, and some extreme traits of Cucurbita flowers (massive rewards, flower size, phenology).

Eupatorium capillifolium essential oil: chemical composition, antifungal activity, and insecticidal activity.

Natural plant extracts often contain compounds that are useful in pest management applications. The essential oil of Eupatorium capillifolium (dog-fennel) was investigated for antifungal and insecticidal activities. Essential oil obtained by hydrodistillation of aerial parts was analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC/MS). The major components were determined to be thymol methyl ether (=methyl thymol) (36.3%), 2,5-dimethoxy-p-cymene (20.8%) and myrcene (15.7%). Antifungal activity of the essential oil was weak against the plant pathogens Colletotrichum acutatum, C. fragariae, and C. gloeosporioides in direct bioautography assay. The E. capillifolium oil showed promising repellent activity against the yellow fever mosquito Aedes aegypti, whereas the oil exhibited moderate activity against the mosquito's first instar larvae in a high throughput bioassay. Topical applications of the oil showed no activity against the blood-feeding female adults of A. aegypti. Eupatorium capillifolium essential oil showed a linear dose response between adult lace bug (Stephanitis pyrioides) mortality and increasing oil concentration in an adulticidal activity bioassay. The dog-fennel oil was more potent than the conventional insecticide malathion. In conclusion, these combined results showed Eupatorium capillifolium oil is a promising novel source of a biological insecticide with multiple modes of action.

Antifungal and insecticidal activity of two Juniperus essential oils.

Essential oils of two Tibetan Junipers Juniperus saltuaria and J. squamata var. fargesii (Cupressaceae) were obtained by distilling dried leaves and branches using a Clevenger apparatus. Sixty-seven compounds from J. saltuaria and 58 from J. squamata var. fargesii were identified by gas chromatography-mass spectrometry (GC-MS). Both essential oils contained similar ratios of four abundant monoterpenoids: 44 and 35% sabinene, 13 and 9% elemol, 8 and 7% terpinen-4-ol, and 4 and 17% alpha-pinene, respectively. These oils had antifungal activity based on a direct bioautography assay of Colletotrichum acutatum, C. fragariae, and C. gloeosporioides, and insecticidal activity based on serial-time mortality bioassay of azalea lace bugs, Stephanitis pyrioides. Antifungal activity of Juniperus oils was weak when compared with commercial fungicides such as benomyl and captan. Whole Juniperus oils at quarter the dosage used against Colletotrichum species were more insecticidal than 10 mg/mL malathion, killing > or =70-90% adult lace bugs after 4 hours of exposure. Rf values of 0.18 for J. saltuaria oil and 0.19 for J. squamata oil indicated lipophilic monoterpenes which were the putative sources of biological activity.

Insecticidal activity of 23 essential oils and their major compounds against adult Lipaphis pseudobrassicae (Davis) (Aphididae: Homoptera).

Essential oils from 23 species of plants comprising 14 genera and 4 plant families were obtained by Clevenger-type water distillation. The major compounds in these essential oils were identified with GC-MS and their insecticidal activity against adult turnip aphids, Lipaphis pseudobrassicae (Davis), tested with dosage-mortality bioassays. We examined mortality only for viviparous adults because sizeable aphid populations on crucifer (Brassicaceae) hosts are largely produced by these wingless, parthenogenic females. Twenty-two of the oils were directly applied to aphid females in randomized blocks at concentrations of 0.0, 1.0, 2.5, 5.0 and 10.0 mg ml(-1). Essential oils mixed with a non-toxic emulsifying agent, dimethyl sulfoxide (DMSO), more easily penetrated the waxy insect cuticle. Probit analysis and LC(50) at three different exposures showed aphids were quickly incapacitated and killed by aliphatic aldehydes, phenols and monocyclic terpenes contained in Bifora and Satureja oils and at applied concentrations as low as 0.3 to 1.0 mg ml(-1). Only enough Pimpinella isaurica oil and its three phenylpropanoid fractions were available for testing at a single concentration of 10 mg ml(-1). We could not spare any additional P. isaurica oil for testing at other concentrations. Phenylpropanoids isolated from P. isaurica oil when recombined or left naturally blended in the oil were highly bioactive against L. pseudobrassicae at 10 mg ml(-1).

Nectar robbery by bees Xylocopa virginica and Apis mellifera contributes to the pollination of rabbiteye blueberry.

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.