Project Number: 2080-21000-017-23-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Aug 1, 2018
End Date: Jul 31, 2019
Four main objectives will be met over 2.5 years of research. This NACA funding is for year 1, and some parts of each objective will be conducted. 1. Search data collected from Utah field studies in 2011 and 2014 for determining timing and conditions for infestation by parasites and parasitoids in commercial shelters during alfalfa leafcutting bee nesting season. 2. Determine prewintering and overwintering conditions for Melittobia and Pteromalus using alfalfa leafcutting prepupae as hosts. 3. Determine Melittobia and Pteromalus life stages that overwinter with managed alfalfa leafcutting bees. 4. Monitor Melittobia and Pteromalus life cycles during bee incubation to determine if there is overlap of parasitoid emergence and if a common protocol can be employed to monitor and curtail infestations.
Methods: Objective 1. Data have been collected and entered into a computer database for contents of all nests sampled weekly in 2011 and 2014 from a Utah alfalfa field. The dates of recorded parasitism, nest location in the shelter, cell position in the nest, and temperature data from bee boards will be correlated with the incidence of parasitism. From these data, we can learn about wasp life cycles during the bee flight season and how they match the emergence of second generation bees and synchronization with bee diapause and overwintering. Methods: Objectives 2-4. Based on new understanding of parasitoid life cycles in Objective 1, in late summer through early fall 2018, we will design a study that subjects parasitized prepupae in nest cells to various prewintering temperatures (constant and fluctuating) and then different timings of placement into winter storage (Oct. – Dec.) (Obj. 2). From these overwintering cells, we will assess which regimens allow survival of which wasp life stages from winter through summer incubation in 2019 (Obj. 3). Both in Petri dishes (small samples) and in large commercial bee trays, we will monitor the timing of emergence from these same cells and other parasitized cells we collect from grower stocks of alfalfa leafcutting bees to determine the timing of Melittobia and Pteromalus adult emergence while in incubation (Obj. 4). We also will observe the effect of dichlorvos on each wasp species to evaluate efficacy of this pesticide. Black lights and flat sticky traps in trays also will be used to help monitor for adult wasp emergence (Obj. 4).