Evaluating the Impact of Post-Emergence Weed Control in Honeybee Colonies Located in Different Agricultural Surroundings

Effects of plant protection products on ecosystem functions provided by terrestrial invertebrates

Plant protection products (PPP) are extensively used to protect plants against harmful organisms, but they also have unintended effects on non-target organisms, especially terrestrial invertebrates. The impact of PPP on ecosystem functions provided by these non-target invertebrates remains, however, unclear. The objectives of this article were to review PPP impacts on the ecosystem functions provided by pollinators, predators and parasitoids, and soil organisms, and to identify the factors that aggravate or mitigate PPP effects. The literature highlights that PPP alter several ecosystem functions: provision and maintenance of biodiversity, pollination, biotic interactions and habitat completeness in terrestrial ecosystems, and organic matter and soil structure dynamics. However, there are still a few studies dealing with ecosystem functions, with sometimes contradictory results, and consequences on agricultural provisioning services remain unclear. The model organisms used to assess PPP ecotoxicological effects are still limited, and should be expanded to better cover the wide functional diversity of terrestrial invertebrates. Data are lacking on PPP sublethal, transgenerational, and "cocktail" effects, and on their multitrophic consequences. In empirical assessments, studies on PPP unintended effects should consider agricultural-pedoclimatic contexts because they influence the responses of non-target organisms and associated ecosystem functions to PPP. Modeling might be a promising way to account for the complex interactions among PPP mixtures, biodiversity, and ecosystem functioning.

Relative impacts of Varroa destructor (Mesostigmata:Varroidae) infestation and pesticide exposure on honey bee colony health and survival in a high-intensity corn and soybean producing region in northern Iowa

The negative effects of Varroa and pesticides on colony health and survival are among the most important concerns to beekeepers. To compare the relative contribution of Varroa, pesticides, and interactions between them on honey bee colony performance and survival, a 2-year longitudinal study was performed in corn and soybean growing areas of Iowa. Varroa infestation and pesticide content in stored pollen were measured from 3 apiaries across a gradient of corn and soybean production areas and compared to measurements of colony health and survival. Colonies were not treated for Varroa the first year, but were treated the second year, leading to reduced Varroa infestation that was associated with larger honey bee populations, increased honey production, and higher colony survival. Pesticide detections were highest in areas with high-intensity corn and soybean production treated with conventional methods. Pesticide detections were positively associated with honey bee population size in May 2015 in the intermediate conventional (IC) and intermediate organic (IO) apiaries. Varroa populations across all apiaries in October 2015 were negatively correlated with miticide and chlorpyrifos detections. Miticide detections across all apiaries and neonicotinoid detections in the IC apiary in May 2015 were higher in colonies that survived. In July 2015, colony survival was positively associated with total pesticide detections in all apiaries and chlorpyrifos exposure in the IC and high conventional (HC) apiaries. This research suggests that Varroa are a major cause of reduced colony performance and increased colony losses, and honey bees are resilient upon low to moderate pesticide detections.

Effects of glyphosate exposure on honeybees

Honeybees show an important pollination ability and play vital roles in improving crop yields and increasing plant genetic diversity, thereby generating tremendous economic benefits for humans. However, honeybee survival is affected by a number of biological and abiotic stresses, including the effects of fungi, bacteria, viruses, parasites, and especially agrochemicals. Glyphosate, a broad-spectrum herbicide that is primarily used for weed control in agriculture, has been reported to have lethal and sublethal effects on honeybees. Here, we summarize recent advances in research on the effects of glyphosate on honeybees, including effects on their behaviors, growth and development, metabolic processes, and immune defense, providing a detailed reference for studying the mechanism of action of pesticides. Furthermore, we provide possible directions for future research on glyphosate toxicity to honeybees.