Stress-induced septicemia as an impediment to laboratory rearing of the fruit fly parasitoid Biosteres (opius) longicaudatus (Hymenoptera: Braconidae) and the Caribbean fruit fly Anastrepha suspensa (Diptera: Tephritidae)

High pupal mortality experienced during laboratory rearing of Biosteres longicaudatus, a parasitoid of the Caribbean fruit fly Anastrepha suspensa was attributed primarily to the action of two species of opportunistic pathogens, Serratia marcescens and Pseudomonas aeruginosa. These bacteria were best able to overwhelm both parasitized and nonparasitized fly larvae and pupae when they were subjected to thermal stress (rearing temperatures >30°C). Methenamine mandelate chemotherapy had no prophylactic effect, but potentially deleterious side effects (aberrant fly premating sounds) were caused by incorporation of this antibiotic in the A. suspensa larval rearing medium. Control was effected by optimizing the cultural conditions rather than by the use of antibiotics.