Physical and Physiological Factors Influence Behavioral Responses of Cochliomyia macellaria (Diptera: Calliphoridae) to Synthetic Attractants.

Volatile chemicals from waste artificial larval media as well as from bovine blood inoculated with bacteria isolated from screwworm-infested wounds attract gravid females of Cochliomyia hominivorax Coquerel and Cochliomyia macellaria (F.). Chemicals identified from volatiles are dimethyl disulfide, dimethyl trisulfide, phenol, p-cresol, and indole; a blend of these attracted females to oviposit. Present studies investigated the effectiveness of these compounds, either in a blend or individually as potential oviposition attractants. Tests were conducted to determine the effects of gender, ovarian age, and the color and type of substrates on attraction response and oviposition of C. macellaria adults. Results showed that substrates treated with dimethyl trisulfide (DMTS) alone or the five-compound blend alone attracted significantly more gravid females than other chemicals. Black substrates treated with DMTS attracted more gravid flies than did the yellow substrates. Yellow substrates treated with indole attracted more males and nongravid females. In oviposition tests, females deposited significantly more eggs on meat-based substrates than those without meat. These findings suggest that several factors have to be considered for developing an effective oviposition attractant that should include effectiveness of individual chemicals used, the ratio of the chemicals in a blend, and their concentrations. Also, an effective trap design will need to consider using suitable color which will selectively attract gravid females.