Location: Pollinator Health in Southern Crop Ecosystems Research
Project Number: 6066-30500-001-006-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Aug 3, 2020
End Date: Dec 20, 2024
Objective:
1. Test the utility of wildflowers to recruit native bees onto small farms in Mississippi.
2. Determine if augmentative releases of native bees can improve berry fruit set, fruit size, and growth rate.
3. Develop an oral toxicity test protocol to assess the risk of pesticide residues on native bee health.
4. Test the efficacy of aggregation attractants (pheromones) to boost brood density and distribution in artificial nesting boxes.
5. Through outreach activities, promote the value of native bees as crop pollinators on small farms in Mississippi.
Approach:
The scientific approach will involve field experiments in which wildflower plantings will manipulate native bee abundance in the vicinity of agricultural crops (small fruits) in high tunnel cultivation. Naturally-occurring native bees will be supplemented with augmentative releases on native mason bees (Osmia spp., Hymenoptera, Megachilidae), which will be purchased from commercial suppliers. Timing of bee releases (i.e., emergence from nesting boxes) will coincide with late winter/early spring blooming of strawberries and blueberries growing in soilless potting mix in 2-L plastic pots. A completely randomized design will be used with control plants isolated from bee contact or visitation, i.e., pollination. Bee abundance will be monitored weekly and fruit set, fruit size, and growth rate determined throughout the season from February through May for two consecutive years. To test the effectiveness of nest aggregation attractants, empty nesting boxes designed for Osmia brood production, treated or not treated will attractants, will be deployed in strategic positions in high tunnels in spring and summer seasons. At the end of the summer, 25% of the nesting boxes will be removed from high tunnels. The density and spatial distribution of bee brood in nesting cells will be estimated in treated versus untreated (control) nesting boxes. The presence or absence of brood parasites (cleptoparasites) in nesting cells will be noted.
To develop test procedures to assess pesticide exposure to Osmia bees, 25% of the nesting boxes will be removed from high tunnels in midsummer to collect developing brood (Osmia spp. larvae) with pollen food stores, from within individual nesting cells. The remaining 50% of the nesting boxes will be maintained in the field (high tunnels) throughout the summer, fall, and winter seasons. As an assessment of overwintering survival, emerging Osmia adults will be recorded two to three times per week on small fruit the following spring and summer.
In the laboratory, a feeding bioassay will be developed to induce larvae to feed on pollen treated with a range of pesticide concentrations. The effects of pesticide class and concentration on brood development and survival will be determined in replicated glass Petri dish arenas, maintained in environmental growth chambers. In addition, pollen balls in nesting cells (food for developing larvae) will be sent-out for pesticide analysis to determine the presence of pesticide residues. Also, soil from partitions between nesting cells will be sent-out for analysis, since adult bees could have harvested soil (mud) contaminated with pesticide residues while constructing brood nesting chambers during spring and early summer.
The expected results from this research will be new techniques to encourage the establishment of native bee populations on and near small farms for pollination of small fruits and new methods to assess pesticide risk on native bee health. Through outreach activities, the value of native bees as crop pollinators on small farms will be promoted.
