Stimulation of oogenesis by proteinaceous adult diets for screwworm, Cochliomyia hominivorax (Diptera: Calliphoridae)

The influence of protein in the adult diet on first cycle gonotrophic development was examined in newly colonized screwworm flies, Cochliomyia hominivorax (Coquerel), reared on an artificial larval diet and bred in subsequent generations from females stimulated to oviposit only after all individuals in a colony were expected to have matured their eggs. This latter criterion was established with the goal of reducing selection for early ovarian maturity and increased autogeny. Under these conditions, supplementing the diet with raw meat during the first week after adult emergence hastened egg maturation by two to four days or more, increased the percentage of seven- to ten-day-old females that was gravid by 45%, and boosted the number of eggs per gravid female by c. 30%. The serous discharge from screwworm-infested sheep wounds, a casein-salt mixture, or casein in potassium hydroxide was as effective as raw meat. Addition of B vitamins to the casein-salt mixture was without further effect. The measures taken to reduce selection for altered gonotrophic development were not critically evaluated here, but they appeared successful in that age and protein affected ovarian maturation rates similarly in F-2 and F-27. Fecundity measured as eggs matured per gravid female differed between generations, but appeared correlated with size differences that were unrelated to colonization duration.