Honey bee colony behavior and ontogeny are adversely affected when exposed to a pesticide-contaminated environment.

Honey bees exhibit age polyethism and thus have a predictable sequence of behaviors they express through developmental time. Numerous laboratory studies show exposure to pesticides may impair critical honey bee behaviors (brood care, foraging, egg-laying, etc.) that adversely affect colony productivity and survival. There are fewer studies that examine the impacts of pesticides in natural field settings, especially given the challenges of implementing treatment groups and controlling variables. This study helps address the need for impact studies on pollinators under field conditions to assess the consequences of chemical overuse and dependency in agricultural and urban landscapes. To assess the impact of systemic pesticides in a natural field setting on worker bee behavioral development, observation hives were established to monitor changes in behaviors of similarly aged workers and sister queens within 2 experimental groups: (i) colonies located near point-source systemic pesticide pollution (pesticide contaminated treatment), and (ii) colonies embedded within a typical Midwestern US agricultural environment (control). In this study, worker bees in the contaminated environment exhibited important and biologically significant behavioral differences and accelerated onset of hive tasks (i.e., precocious behavioral development) compared to similarly aged bees at the control site. Queen locomotion was largely unaffected; however, the egg-laying rate was reduced in queens at the contaminated (treated) site. These results show that environmental pesticide exposure can disrupt colony function and adversely affect worker bee behavioral maturation, leading to reduced worker longevity and decreased colony efficiency.

Re-using food resources from failed honey bee (Apis mellifera L.) colonies and their impact on colony queen rearing capacity.

For over a decade, beekeepers have experienced high losses of honey bee (Apis mellifera L.) colonies due to a variety of stressors including pesticide exposure. Some of these chemical stressors may residually remain in the colony comb and food resources (pollen and nectar) of failed colonies and be later re-used by beekeepers when splitting and building back new colonies. The practice of re-using comb from previously perished colonies (termed "deadout") is common in beekeeping practice, but its role in affecting colony health is not well understood. Here, we evaluate the impact of reused, pesticide-contaminated "deadout" combs on colony function during the process of replacing a queen bee. Queenless microcolonies were established to monitor queen rearing capacity in two treatment groups: (1) colonies given frames containing food resources from deadout colonies in control "clean" apiaries and, (2) colonies given frames containing "contaminated" resources from deadout colonies originating from apiaries experiencing chronic pesticide exposure from widespread systemic pesticide pollution (including neonicotinoid insecticides: clothianidin and thiamethoxam). Results indicate that colonies given pesticide-contaminated resources produced fewer queen cells per colony and had a lower proportion of colonies successfully raising a functional, diploid egg-laying queen. This research highlights the deleterious effects of re-using deadout combs from colonies previously lost due to pesticide contamination.

Patch utilization and flower visitations by wild bees in a honey bee-dominated, grassland landscape.

Understanding habitat needs and patch utilization of wild and managed bees has been identified as a national research priority in the United States. We used occupancy models to investigate patterns of bee use across 1030 transects spanning a gradient of floral resource abundance and richness and distance from apiaries in the Prairie Pothole Region (PPR) of the United States. Estimates of transect use by honey bees were nearly 1.0 during our 3.5-month sampling period, suggesting honey bees were nearly ubiquitous across transects. Wild bees more frequently used transects with higher flower richness and more abundant flowers; however, the effect size of the native flower abundance covariate ( ß ^ native  = 3.90 ± 0.65 [1SE]) was four times greater than the non-native flower covariate ( ß ^ n o n - n a t i v e  = 0.99 ± 0.17). We found some evidence that wild bee use was lower at transects near commercial apiaries, but the effect size was imprecise ( ß ^ distance  = 1.4 ± 0.81). Honey bees were more frequently detected during sampling events with more non-native flowers and higher species richness but showed an uncertain relationship with native flower abundance. Of the 4039 honey bee and flower interactions, 85% occurred on non-native flowers, while only 43% of the 738 wild bee observations occurred on non-native flowers. Our study suggests wild bees and honey bees routinely use the same resource patches in the PPR but often visit different flowering plants. The greatest potential for resource overlap between honey bees and wild bees appears to be for non-native flowers in the PPR. Our results are valuable to natural resource managers tasked with supporting habitat for managed and wild pollinators in agroecosystems.

An updated genetic marker for detection of Lake Sinai Virus and metagenetic applications.

BACKGROUND: Lake Sinai Viruses (LSV) are common RNA viruses of honey bees (Apis mellifera) that frequently reach high abundance but are not linked to overt disease. LSVs are genetically heterogeneous and collectively widespread, but despite frequent detection in surveys, the ecological and geographic factors structuring their distribution in A. mellifera are not understood. Even less is known about their distribution in other species. Better understanding of LSV prevalence and ecology have been hampered by high sequence diversity within the LSV clade. METHODS: Here we report a new polymerase chain reaction (PCR) assay that is compatible with currently known lineages with minimal primer degeneracy, producing an expected 365 bp amplicon suitable for end-point PCR and metagenetic sequencing. Using the Illumina MiSeq platform, we performed pilot metagenetic assessments of three sample sets, each representing a distinct variable that might structure LSV diversity (geography, tissue, and species). RESULTS: The first sample set in our pilot assessment compared cDNA pools from managed A. mellifera hives in California (n = 8) and Maryland (n = 6) that had previously been evaluated for LSV2, confirming that the primers co-amplify divergent lineages in real-world samples. The second sample set included cDNA pools derived from different tissues (thorax vs. abdomen, n = 24 paired samples), collected from managed A. mellifera hives in North Dakota. End-point detection of LSV frequently differed between the two tissue types; LSV metagenetic composition was similar in one pair of sequenced samples but divergent in a second pair. Overall, LSV1 and intermediate lineages were common in these samples whereas variants clustering with LSV2 were rare. The third sample set included cDNA from individual pollinator specimens collected from diverse landscapes in the vicinity of Lincoln, Nebraska. We detected LSV in the bee Halictus ligatus (four of 63 specimens tested, 6.3%) at a similar rate as A. mellifera (nine of 115 specimens, 7.8%), but only one H. ligatus sequencing library yielded sufficient data for compositional analysis. Sequenced samples often contained multiple divergent LSV lineages, including individual specimens. While these studies were exploratory rather than statistically powerful tests of hypotheses, they illustrate the utility of high-throughput sequencing for understanding LSV transmission within and among species.