Location: Invasive Species and Pollinator Health
Project Number: 2030-22000-033-012-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Oct 1, 2022
End Date: Jun 30, 2023
Objective:
The objectives of this project are to: 1) mass rear the parasitic wasp Gryon aetherium for releases of this new agent within the state of California; 2) release G. aetherium in areas of the state with bagrada bug outbreaks; 3) survey and monitor California for changes in the density and distribution of bagrada bug and G. aetherium.
Approach:
Bagrada bugs will be maintained in a small walk-in rearing room provided with some natural light. Bugs will be cultured at relatively high temperatures required by them for oviposition, 30°C, with 16:8 h L:D, ambient relative humidity. Adult bagrada bugs will be provided with a sand substrate for oviposition. Eggs will be transferred from sand to and glued to strips of card stock. Each card strip will then be placed into a small ca. 50 ml plastic vial with snap-on lid. Parasitoids will be exposed to young eggs (24 to 72 hrs old) before they turn pink. Adult parasitoids will emerge from these eggs within in 12-18 days and will be transferred to a small holding container until released into the field or used to maintain the colony. Locations will be selected for release of the parasitoid using information from County and agriculture industry collaborators to find outbreaks of bagrada bug, preferably in organic systems. These locations will be surveyed for the presence of G. aetherium prior to making releases using the sifted soil tray method detailed below. Post-release establishment will be tested by surveying for the presence of G. aetherium using the same type of soil trays placed in the each release location approximately one month after releases are made.
The parasitoid will be surveyed across the current range of bagrada bug in California. Trays filled with sifted soil will be placed under plants heavily infested by bagrada bug to provide an attractive egg laying medium for bagrada bug females. A piece of folded cardstock will be placed over the trays to provide shade. After 5–7 days these trays will be collected, and the soil sifted, to remove and count eggs. These will be held until emergence of either bagrada bugs or parasitoids and the total numbers of each recorded to determine percent parasitism. Unhatched eggs will be dissected to determine if undeveloped parasitoids are present.
