Location: Southern Horticultural Research
Project Number: 6062-21430-003-29-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2018
End Date: Dec 31, 2019
Non-Apis bees are important pollinators of numerous wild and cultivated crops. In commercial crop production systems, they are often exposed to various agricultural chemicals that pose serious threats to their survival, and over a period of time, such regular exposure may subsequently affect biodiversity and abundance of these bees. In other settings (such as backyard gardens and urban landscapes) bees are also regularly exposed to numerous toxic pesticides, and impact of such exposure often goes unnoticed. So far, majority of studies examining general bee health in these settings have primarily been focused on honey bees. Considering the ecosystem services of non-Apis bees, it is important to conduct lab and field studies to assess ecotoxicology and risk of various pesticides and their mixtures (used in the aforementioned settings) to non-Apis bees. The main objectives of this project are: 1) to examine environmental threats to non-Apis bees in different ecosystems in Midsouthern region, 2) to develop baseline toxicity information of various pesticides used in agricultural and non-agricultural systems to non-Apis bees, 3) to conduct ecotoxicological risk assessment of various pesticides for major species of non-Apis bees, and 4) to develop strategies to mitigate ecotoxicological risk associated with pesticide applications to non-Apis bees.
Obj. 1: A multi-year field study will be conducted utilizing different sampling methods, such as trap-nests, and passive collection traps (vane and pan traps). Samples will be collected from different locations and ecosystems in the Midsouthern region. Samples of bees from passive traps, and samples of pollen mass, nest substrate and bees (developing stages) from trap-nests will be categorized and processed in lab, and will be outsourced for pesticide and pathogen analysis. Obj. 2: Various lab studies will be conducted to develop baseline information of pesticide toxicity to three non-Apis bee species (viz. blue orchard bee/mason bee, leafcutter bee, and bumblebee). Common formulated pesticides (and their mixtures) that are currently used in agricultural and non-agricultural systems (for pest management) will be assessed via multiple and replicated contact and ingestion bioassays. In regard to each species, relative LD50 and LC50 values of each treatment will be determined. Obj. 3: Lab and field studies will be conducted to assess ecotoxicological risk of various pesticides for three major species of non-Apis bees. Various field-realistic pesticide exposure scenarios will be simulated in lab and semi-field environment, and toxicity from such exposures will be assessed for each bee species. Toxicity responses of male and female orchard bees and leafcutter bees will also be assessed. Observations will be recorded for an extended period of time (96 hours) after exposure. Based on the results of Obj. 2 and Obj. 3, hazard quotient will be determined for all pesticide treatments. In addition, sub-lethal effects of pesticide treatments will be examined whenever possible. Obj. 4: Based on the findings from Objectives 1-3, an integrated strategy utilizing modified bee habitat will be developed to mitigate field-realistic risk of pesticide applications to non-Apis bees. Different locations in farmscape (where pesticides are sprayed) will be selected for this multi-year field study. Native flowering habitats will be established in half of the locations. Nest-boxes containing orchard bees and leafcutter bees and different types of nesting substrates will be placed in both types of farmscape regimes (i.e., landscape with and without native flowering habitat for bees). In addition, bumblebee colonies will also be placed in these locations. Bumblebee colony health will be monitored at different time intervals after placement, while the health of orchard bees and leafcutter bees (placed in both farmscape regimes) will be assessed during the winter season.