Relationships of Larval Rearing Variables to Fly Attraction and Oviposition Responses in the Screwworm, Cochliomyia Hominivorax (Diptera: Calliphoridae)1

Abstract

Responsiveness of gravid screwworm flies, Cochliomyia hominivorax, in oviposition and olfactometer bioassays was examined in relation to mean larval weight, mean pupal weight, and survival to the pupal stage in the larval rearing groups that supplied the test females. Weights were not of value for predicting adult behavior in bioassays, but the percentage of insects surviving from egg to pupal stage was positively and linearly correlated with oviposition and attraction responses (r² = 0.48 and 0.57, respectively). Rearing data compiled over a 21-month interval that included the period of behavioral testing were used to establish that the correlations most likely arose from inadequate control over variables that operated prior to the pupal stage and affected both screwworm survival and the subsequent behavioral responsiveness of surviving insects. Survival in larval groups did not vary with parental age at oviposition or with the temperature at which parental insects had been held as pupae, but circumstantial evidence suggested that composition of the larval starting diet affected survival and adult behavior.