Project Number: 6205-32000-035-00
Project Type: Appropriated

Start Date: Oct 01, 2009
End Date: Sep 30, 2014

Objective:
Objective 1: Determine the ability of screwworm flies to cross major geographic barriers. Objective 2: Develop a strain of screwworm fly that produces only males. Sub-objective 2a: Develop a genetic sexing system in the horn fly, a species closely related to screwworm, as a model system to be applied to screwworms. Sub-objective 2b: Using information and techniques developed with horn flies, develop a genetic sexing, males-only strain of screwworms. Objective 3: Identify chemical oviposition attractants that can be used in attract-and-kill and for improved rearing. Sub-objective 3a: Identify the natural volatiles from bacteria-inoculated and incubated bovine blood that are responsible for attracting gravid screwworm flies to oviposit. Sub-objective 3b: Identify synthetic compounds with equivalent attraction to gravid screwworm flies for depositing eggs as natural volatiles from bacteria-inoculated and incubated bovine blood. Objective 4: Develop new surveillance methods based on oviposition attractants.

Approach:
For our first objective we will identify four islands, in the Republic of Panama, where sterile screwworm flies marked with fluorescent powder will be released. Traps, placed on the mainland, will be used to detect if the screwworms crossed the water 'barrier'. The second objective, development of a male-only strain of screwworm, will be approached by an ARS collaborator first developing transgenic techniques in a related species, the horn fly. Once genetic transformation is accomplished in horn flies the techniques will be transferred to the screwworm. This two-step approach is necessary because 1) the screwworm is a quarantined pest and adequate facilities for its study are not present in the U.S., and 2) the collaborator has extensive genetic information/experience with horn flies that will directly transfer to screwworms. Volatiles from bacteria-infested wounds that previously were shown to attract female screwworms will be collected and identified with standard gas chromatograph and mass spectrometry to approach our third objective. Existing 'synthetic' chemicals that are equivalent to the 'natural' volatiles identified as most attractive will then be evaluated for attractiveness to female screwworms using standard bio-assay techniques. Our approach to the fourth objective will be a combination of evaluating the attractiveness of trap design (color, shape, and size) along with the use of volatiles, natural or synthetic as determined from objective 3, that are attractive to female screwworms under field conditions.