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Cold winter temperatures govern the distribution and abundance of many insect species, but refugia that provide microclimates can moderate temperature-driven mortality. Winter temperatures have been implicated in limiting the survival and range of Piezodorus guildinii (Westwood) (Hemiptera: Pentatomidae; redbanded stink bug), an economically damaging invasive pest in the southeastern United States, but the role of refugia in overwintering survival of this pest is poorly understood. We conducted 2 studies in successive years to evaluate how leaf litter from hardwoods, pines, and soybeans modulate overwintering site selection and survival of P. guildinii. In the second-year study, we also quantified the buffering effect of the 3 leaf litter types compared to ambient conditions and assessed diapause. In the first-year study, we found that stink bugs preferentially dispersed into leaf litter compared with remaining unsheltered on bare soil; no clear preference among leaf litter types was found. In the second year, however, no clear differences were found among leaf litter types and bare soil. Means of daily minimum temperatures under leaf litter were at least 3.0 ± 0.9 °C (SE) warmer and generally less variable than ambient conditions. While high mortality in both studies illustrates that more work must be done to fully understand overwintering survival, limited survival through potentially lethal conditions in the first-year study nonetheless emphasizes the possibility of populations persisting and rebounding in the following spring. Furthermore, our study highlights the potential for stink bugs to persist in areas with lethal ambient temperatures by dispersing into widely available substrates. [ABSTRACT FROM AUTHOR]

Pesticide exposures can have detrimental impacts on bee pollinators, ranging from immediate mortality to sub-lethal impacts. Flupyradifurone is the active ingredient in Sivanto™ and sulfoxaflor is the active ingredient in Transform®. They are both relatively new insecticides developed with an intent to reduce negative effects on bees, when applied to bee-attractive crops. With the growing concern regarding pollinator health and pollinator declines, it is important to have a better understanding of any potential negative impacts, especially sub-lethal, of these pesticides on bees. This study reports novel findings regarding physiological stress experienced by bees exposed to field application rates of these two insecticides via a Potter Tower sprayer. Two contact exposure experiments were conducted—a shorter 6-hour study and a longer 10-day study. Honey bee mortality, sugar syrup and water consumption, and physiological responses (oxidative stress and apoptotic protein assays) were assessed in bees exposed to Sivanto™ and Transform®, and compared to bees in control group. For the longer, 10-day contact exposure experiment, only the Sivanto™ group was compared to the control group, as high mortality recorded in the sulfoxaflor treatment group during the shorter contact exposure experiment, made the latter group unfeasible to test in the longer 10-days experiment. In both the studies, sugar syrup and water consumptions were significantly different between treatment groups and controls. The highest mortality was observed in Transform® exposed bees, followed by the Sivanto™ exposed bees. Estimates of reactive oxygen/nitrogen species indicated significantly elevated oxidative stress in both pesticide treatment groups, when compared to controls. Caspase-3 protein assays, an indicator of onset of apoptosis, was also significantly higher in the pesticide treatment groups. These differences were largely driven by post exposure duration, indicating sub-lethal impacts. Further, our findings also emphasize the need to revisit contact exposure impacts of Sivanto™, given the sub-lethal impacts and mortality observed in our long-term (10-day) contact exposure experiment. [ABSTRACT FROM AUTHOR]

Although poor nutrition is cited as one of the crucial factors in global pollinator decline, the requirements and role of several important nutrients (especially micronutrients) in honey bees are not well understood. Micronutrients, viz. phytosterols, play a physiologically vital role in insects as precursors of important molting hormones and building blocks of cellular membranes. There is a gap in comprehensive understanding of the impacts of dietary sterols on honey bee physiology. In the present study, we investigated the role of 24-methylenecholesterol—a key phytosterol—in honey bee nutritional physiology. Artificial diets with varying concentrations of 24-methylenecholesterol (0%, 0.1%. 0.25%, 0.5%, 0.75%, and 1% dry diet weight) were formulated and fed to honey bees in a laboratory cage experiment. Survival, diet consumption, head protein content, and abdominal lipid contents were significantly higher in dietary sterol-supplemented bees. Our findings provide additional insights regarding the role of this important sterol in honey bee nutritional physiology. The insights gleaned from this study could also advance the understanding of sterol metabolism and regulation in other bee species that are dependent on pollen for sterols, and assist in formulation of a more complete artificial diet for honey bees (Apis mellifera Linnaeus, 1758) (Hymenoptera: Apidae). [ABSTRACT FROM AUTHOR]

28-13C]-24-Methylenecholesterol, a labelled form of a phytosterol found in pollen that is a critical micronutrient for honey bees (Apis mellifera, L.), was prepared in six steps and 20% overall yield from 3'-hydroxy-5-cholenoic acid. The acid was converted to the corresponding isopropyl ketone via its TBS ether protected Weinreb amide derivative and the carbonyl group was subsequently methylenated (in 51% yield) by a Julia-Kocienski olefination using 1-tert-butyl-1H-tetrazol-5-yl [13C]-methyl sulfone to introduce the 13C-labelled methylene carbon-atom. [ABSTRACT FROM AUTHOR]