Location: Invasive Species and Pollinator Health
Project Number: 2030-22300-032-020-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Nov 1, 2020
End Date: Oct 31, 2025
The primary objective of this project is to develop a proactive classical biological control program that uniquely targets T. absoluta, is naturally self-sustaining, and bolsters the pest management program for California-grown tomatoes.
This project aims to deliver a science-driven proactive classical biological control program for T. absoluta in California. We will import the Peruvian strain of Dolichogenidae gelechiidivoris that is most likely to establish in California for this purpose. A representative selection of North American non-target lepidoptera in the larval stage will be offered to experimental female D. gelechiidivoris in a series of two-tiered exposure studies, consisting of no-choice and choice tests. Ideally, laboratory testing will be conducted during spring-summer when these insects are naturally active in the field and can be reared in the lab. By design, no-choice experiments will evaluate the oligophagy of D. gelechiidivoris under maximum non-target exposure in quarantine conditions. T. absoluta 1st or 2nd instar larvae will be used as positive controls in these experiments. However, should access to T. absoluta become limiting in this first tier of testing, we will consider using either K. lycopersicella or P. operculella. Preliminary experiments will help confirm if these known alternative hosts can be used as positive controls in California. Data collection for all trials will include a measure of parasitoid offspring egg-adult development time; parasitoid offspring sex ratios; and levels of non-target host mortality caused by D. gelechiidivoris attack, including attempted parasitism, successful parasitism, and host-feeding. Timed visual observations or video recordings may be integrated into this tier to learn valuable behavioral information about the range, quality and duration of categorical contact interactions between D. gelechiidivoris and non-targets, including host inspection, host attack, and host rejection. At the completion of all no-choice testing, the group of non-targets whose mortality was not caused directly by D. gelechiidivoris will be excluded from further testing and placed in the no-risk category. The remaining group of on-target species attacked by D. gelechiidivoris will be included in choice-testing trials to measure the host preference of D. gelechiidivoris when each non-target is offered in a paired combination with T. absoluta. Tuta absoluta larvae will be included in this second tier of testing as it is assumed that any problems in obtaining this target species will have been cleared by this point.