Location: Horticultural Crops Disease and Pest Management Research Unit
Project Number: 2072-22000-044-042-T
Project Type: Trust Fund Cooperative Agreement
Start Date: Jun 3, 2024
End Date: May 31, 2027
Objective:
ARS will test Agragene’s sterile male spotted-wing drosophila (SWD) product to suppress wild populations of SWD on blueberry or other small fruits.
Spotted-wing drosophila (SWD; D. suzukii) is an invasive insect pest that infests ripening fruit. It is responsible for severe economic damage in several fruits and berries and is widespread in the U.S. Fruit growers in the U.S. currently use multiple rotating applications of different pesticides to suppress commercial damage in their fields. Agragene has developed a sterile male SWD for release into fruit and berry crops to achieve non-chemical suppression of the wild SWD population. ARS, Corvallis, Oregon, under the guidance of PI who has expertise in SWD behavior, IPM, and experimental approaches in commercially important fruits and berries in the Oregon region.
Approach:
Lab A: To test infestation reduction, sterile males will be released into a cage (75 x 75 x 115 cm) with wild SWD, 5 virgin females and 5 virgin males. Ratios will be 10:1, 0:1 (wild control) or as determined. Fresh fruit will be placed and replaced mid-week for SWD to oviposit for 6 days. Exposed fruit will be collected and developing SWD reared, quantified, and compared to controls to determine population suppression with sterile males. Each treatment will be replicated 19 times.
Additional quality checks are done simultaneously, extra virgin females will be held in diet for a week to check that no pupae appear to confirm that they did not reproduce. Extra sterile males and wild males are held in separate cages to compare longevity in the presence of wild females, food and water.
Longevity check: Send 200+ sterile males. They will be put in the large cages with some wild virgin females, and mortality will be checked. The diet used to feed the flies in the cage, can also be incubated to check for male sterility.
Lab B: A trial with 10:1, 5:1, and 0:1 control will be repeated again with fresher blueberries and replicated ~15 times. Corresponding virgin and sterile male checks will be done simultaneously.
Lab C: Remating will be tested in the same large cages. Virgin females will first be held with sterile males in vials to increase their chances of mating for 2 days. Then virgin females will be transferred into cages with an equal number of wild males and potted blueberry plant with hanging berries. Remating studies have been done in vials or containers and may have overestimated remating due to the close propensity of flies.
Lab D: This will test whether genetic material is transferred to blueberry fruit if mated females lay sterile eggs. Virgin females will be paired with sterile males or with CAS9 males as the positive control. Five females and five males will be placed per cage with diet, water and 4 blueberries. After 4 d, blueberries will be collected, counted for eggs laid per blueberry, and then frozen for genetic analysis. Another set of 4 blueberries will be placed per cage and collected after 3 d. Blueberries are tracked individually from each treatment*rep in well-plates, and for number of eggs. Blueberries are shipped on dry ice to Agragene to test whether CAS9 elements are detectable in the fruit, the number of eggs are recorded to confirm that there should be genetic material. Blueberries are collected within 4 and then 3 d before egg DNA should degrade, and to allow SWD females time to mature eggs. Ongoing shipping tests: Sterile males will be sent in variously packaged boxes for releases. The condition, and emergence of wild SWD will be recorded.
Semi-field trial:
Hoop 1: Experiments will occur in a smaller mesh hoop supported by PVC arcs covering 5 blueberry bushes. Mesh will be weighed down with plywood stakes, closed with clamps, and gaps will be filled with sawdust. These covered blueberries are enclosed in a secondary hoop house structure with vestibules.