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Analysis of trapped honey bee pollen for pesticide residues is the most widely used method of monitoring the amount of pesticide entering colonies and its change over time. In this study, we collected and analyzed pollen from 70 sites across four bee-pollinated crops over two years to characterize the variation in pesticide detection across sites, crops and at different periods during bloom. Hazard Quotient, HQ, is the most common way that pesticide residues are aggregated into a single pesticide hazard value in the current literature. Therefore, change in pesticide hazard (HQ) was quantified in composite pollen samples collected from pollen traps and in pollen color subsamples separated into pollen from the target crop being pollinated and pollen from other plant species. We used our estimates of the variation in HQ to calculate the number of sample location sites needed to detect a 5% annual change in HQ across all crops or within specific crops over a 5-year period. The number of sites required to be sampled varied by crop and year and ranged between 139 and 7194 sites, costing an estimated $129,548 and $3.35 million, respectively. The HQ values detectable for this cost would be 575 and 154. We identified additional factors that complicate the interpretation of the results as a way to evaluate changes in pest management practices at a state level. First, in all but one crop (meadowfoam), the pollen collected from outside the crop honey bee colonies were pollinating comprised a major percentage of the total pollen catch. Moreover, we found that when the overall quantity of pollen from different pollen sources was taken into account, differences in HQ among crops widened. We also found that while HQ estimates remain consistent across the bloom period for some crops, such as cherry, we observed large differences in other crops, notably meadowfoam. Overall, our results suggest the current practice of interpreting pesticides levels in pollen may come with limitations for agencies charged with improving pesticide stewardship due to the high variation associated with HQ values over time and across crops. Despite the limitations of HQ for detecting change in pesticide hazard, there remains a potential for HQ to provide feedback to regulators and scientists on field-realistic pesticide hazard within a landscape. [ABSTRACT FROM AUTHOR]

Novel grazing management practices for livestock and bee health are becoming increasingly crucial in pasture-based farming systems. The effect of pasture type and spring closing dates on lamb liveweight gain, pasture production, botanical composition, bloom density and bee visitation was monitored over 2 years. Total annual dry matter yield (DMY) of diverse pastures in 2020/2021 was 8.8 t DM ha−1. This yield was greater than the DMY obtained from both simple (7.6 t DM ha−1) and legume pastures (6.6 t DM ha−1). In 2021/2022, the total annual DMY of simple (8.6 t DM ha−1) and diverse pastures (9.0 t DM ha−1) was similar. However, the legume pastures produced 27–30% less than simple and diverse pastures. In successive years, lambs grew faster in legume pastures (287, 215 g per head d−1) than diverse (207, 151 g per head d−1) and simple pastures (204, 132 g per head d−1). However, spring liveweight production (kg ha−1 day−1) from pastures did not differ due to the lower stocking density of legume pastures as compared to the other two pasture mixtures. Bloom density (flower/m2) and bee visitation (bees/min−1 m2) were 16 and 40 times greater with legume rather than simple pastures. Bloom density for diverse pastures was also relatively lower than for the legume pastures. Our findings indicated that the diversification of pastures greatly increased pasture productivity, while legume pastures provided the highest bee benefit without penalizing lamb liveweight production in spring. [ABSTRACT FROM AUTHOR]

Forage systems can be designed to produce high quality feed for ruminant livestock while providing habitat for insect pollinators. We compared forage productivity, nutritive value, and selenium uptake as well as late summer nectar production of perennial forage species; alfalfa (Medicago sativa), birdsfoot trefoil (Lotus corniculatus), red clover (Trifolium pratense), sainfoin (Onobrychis viciifolia), and chicory (Cichorium intybus) as monocultures and intercropped with either subterranean clover (Trifolium subterraneum) or balansa clover (Trifolium michelianum) for two successive years in Oregon. Red clover intercropped with balansa clover out‐performed other stands, producing over 11 t DM ha−1 in 2019 and 9.4 t DM ha−1 in 2020. Birdsfoot trefoil and sainfoin mixtures were dominated by subterranean clover, negatively affecting total forage yield and flower abundance. Chicory intercropped with subterranean clover formed a more balanced mixture with improved DM yield and nutritive value relative to chicory monocultures. Chicory was most responsive to Se‐fertilisation in both years, having a higher concentration of Se relative to the other perennial species. Chicory also had high levels of condensed tannins (18.1–43.3 mg/g DM) relative to the other forages (1.8–17.5 mg/g DM). Red clover had the most consistent bloom in 2019, with 170 inflorescences per square meter at peak bloom and yielded an estimated total of 16.9 kg ha−1 sucrose. Birdsfoot trefoil produced the most inflorescences during peak bloom in 2020 at 279 inflorescences per square meter. However, alfalfa had a higher estimated sucrose yield in 2020 at 241 kg ha−1. [ABSTRACT FROM AUTHOR]

Abstract Background There is a major paradox in our understanding of honey bee immunity: the high population density in a bee colony implies a high rate of disease transmission among individuals, yet bees are predicted to express only two-thirds as many immunity genes as solitary insects, e.g., mosquito or fruit fly. This suggests that the immune response in bees is subdued in favor of social immunity, yet some specific immune factors are up-regulated in response to infection. To explore the response to infection more broadly, we employ mass spectrometry-based proteomics in a quantitative analysis of honey bee larvae infected with the bacterium Paenibacillus larvae. Newly-eclosed bee larvae, in the second stage of their life cycle, are susceptible to this infection, but become progressively more resistant with age. We used this host-pathogen system to probe not only the role of the immune system in responding to a highly evolved infection, but also what other mechanisms might be employed in response to infection. Results Using quantitative proteomics, we compared the hemolymph (insect blood) of five-day old healthy and infected honey bee larvae and found a strong up-regulation of some metabolic enzymes and chaperones, while royal jelly (food) and energy storage proteins were down-regulated. We also observed increased levels of the immune factors prophenoloxidase (proPO), lysozyme and the antimicrobial peptide hymenoptaecin. Furthermore, mass spectrometry evidence suggests that healthy larvae have significant levels of catalytically inactive proPO in the hemolymph that is proteolytically activated upon infection. Phenoloxidase (PO) enzyme activity was undetectable in one or two-day-old larvae and increased dramatically thereafter, paralleling very closely the age-related ability of larvae to resist infection. Conclusion We propose a model for the host response to infection where energy stores and metabolic enzymes are regulated in concert with direct defensive measures, such as the massive enhancement of PO activity.

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]

BACKGROUND: Teaching pesticide applicators how to determine a product's toxicity to honey bees (Apis mellifera L.) by understanding the label is a way to reduce honey bee exposure to pesticides. Applicators are currently taught how to interpret labels that follow the United States Environmental Protection Agency's (USEPA's) recommendations for how this toxicity should be communicated. To effectively educate applicators, it must be determined if labels follow USEPA recommendations in how they communicate toxicity to honey bees, and if they do not, what patterns exist in these deviations from the recommendations (hereafter, deviations). RESULTS: As a case study, we analyzed the USEPA master labels of insecticides used in 16 situations where there is concern over Oregon honey bee colony exposure to pesticides. Of the 232 labels analyzed, 31.5% deviated from USEPA recommendations in at least one way. Labels of both commercial and garden products deviated from USEPA recommendations. Products with labels that deviated from USEPA recommendations were found across application situation and active ingredient subgroup. The percentage of products per application situation and per chemical subgroup whose label deviated from USEPA recommendations varied. The most common deviation represented a direct contradiction between the statement used and the toxicity class of the product's active ingredient. CONCLUSION: Applicators will be underprepared to interpret the pesticide labels they see in the field if they are exclusively taught how to interpret labels that follow USEPA recommendations. Applicators should be taught how to interpret a product label that uses non‐USEPA‐recommended statements to communicate toxicity to honey bees. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]