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Browsing by Author "Ohlinger, Bradley D."

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    Apple orchards feed honey bees during, but even more so after, bloom
    Steele, Taylor N.; Schürch, Roger; Ohlinger, Bradley D.; Couvillon, Margaret J. (Wiley, 2022-09-01)
    Many of the fruits that add diversity and nutrition to our diet are wholly or partially dependent upon flower-visiting insects. For example, apples (Malus spp.) are self-incompatible and therefore rely on insect pollinators for fruit development and seed production. Honey bees (Apis mellifera) are often migrated into these orchards when the apples are in bloom. While previous studies have focused on the impact of honey bees to fruit orchards, fewer studies have examined the reciprocal relationship of the orchards to honey bees, particularly if the bees are in the orchard for the entire foraging season, not just during bloom. Here we investigated the foraging dynamics of honey bees in apple orchards in Virginia for two full foraging seasons (April–October, 2018–2019). We decoded, mapped, and analyzed the waggle dances (n = 3710) made by returning foragers, which communicate the distance and direction from the hive to valuable resources, usually nectar or pollen. We found that bees foraged locally at <2 km throughout the season in both 2018 and 2019, with some long-range recruitment of up to 11 km. Contrary to our expectations, apple blooms did not drive honey bee foraging. We determined in our calculations of percent (%) foraging that honey bees recruit more to the apple orchards after the bloom than during the bloom (29.4% vs. 18.6% in 2018 and 28.5% vs. 21.4% in 2019, respectively). Interestingly, honey bees recruited more to forests while the apples bloomed (36.9% and 25.7% in 2018 and 2019, respectively). Lastly, our odds ratio analysis, which includes a distance correction, indicates the honey bees were more than twice as likely to recruit to apple orchards in June, which is after the bloom, than in April or May, which is during the bloom. Our ground truthing revealed that post-bloom apple orchards provided foraging opportunities on the growing understory of red and white clover (Trifolium spp.) and plantain (Plantago spp.). These data might therefore have important implications for best management practice decisions for bees located in fruit orchards.
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    Dance-communicated distances support nectar foraging as a supply-driven system
    Ohlinger, Bradley D.; Schürch, Roger; Silliman, Mary R.; Steele, Taylor N.; Couvillon, Margaret J. (The Royal Society, 2022-08-31)
    Much like human consumers, honeybees adjust their behaviours based on resources' supply and demand. For both, interactions occur in fluctuating conditions. Honeybees weigh the cost of flight against the benefit of nectar and pollen, which are nutritionally distinct resources that serve different purposes: bees collect nectar continuously to build large honey stores for overwintering, but they collect pollen intermittently to build modest stores for brood production periods. Therefore, nectar foraging can be considered a supply-driven process, whereas pollen foraging is demand-driven. Here we compared the foraging distances, communicated by waggle dances and serving as a proxy for cost, for nectar and pollen in three ecologically distinct landscapes in Virginia. We found that honeybees foraged for nectar at distances 14% further than for pollen across all three sites (n = 6224 dances, p < 0.001). Specific temporal dynamics reveal that monthly nectar foraging occurs at greater distances compared with pollen foraging 85% of the time. Our results strongly suggest that honeybee foraging cost dynamics are consistent with nectar supply-driven and pollen demand-driven processes.
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    Honey Bees (Hymenoptera: Apidae) Decrease Foraging But Not Recruitment After Neonicotinoid Exposure
    Ohlinger, Bradley D.; Schürch, Roger; Durzi, Sharif; Kietzman, Parry M.; Silliman, Mary R.; Couvillon, Margaret J. (Oxford University Press, 2021-10-25)
    Honey bees (Linnaeus, Hymenoptera: Apidae) are widely used as commercial pollinators and commonly forage in agricultural and urban landscapes containing neonicotinoid-treated plants. Previous research has demonstrated that honey bees display adverse behavioral and cognitive effects after treatment with sublethal doses of neonicotinoids. In laboratory studies, honey bees simultaneously increase their proportional intake of neonicotinoid-treated solutions and decrease their total solution consumption to some concentrations of certain neonicotinoids. These findings suggest that neonicotinoids might elicit a suboptimal response in honey bees, in which they forage preferentially on foods containing pesticides, effectively increasing their exposure, while also decreasing their total food intake; however, behavioral responses in semifield and field conditions are less understood. Here we conducted a feeder experiment with freely flying bees to determine the effects of a sublethal, field-realistic concentration of imidacloprid (IMD) on the foraging and recruitment behaviors of honey bees visiting either a control feeder containing a sucrose solution or a treatment feeder containing the same sucrose solution with IMD. We report that IMD-treated honey bees foraged less frequently (–28%) and persistently (–66%) than control foragers. Recruitment behaviors (dance frequency and dance propensity) also decreased with IMD, but nonsignificantly. Our results suggest that neonicotinoids inhibit honey bee foraging, which could potentially decrease food intake and adversely affect colony health.