STUDIES ON THE HOUSEFLY (MUSCA DOMESTICA L.): II. THE EFFECTS OF LOW TEMPERATURES ON LABORATORY-REARED PUPARIA

Abstract

Investigations are reported on factors influencing the survival of housefly (Musca domestica L.) puparia exposed to different intensities of low temperature storage above 1 °C. Survival was decreased by lowering the temperature of storage and by increasing the duration of the storage period, or both. Mortality of adults following puparial storage was influenced by the type of rearing container used, crowding, age of puparia, humidity, concentration of gases in the pupal rearing chambers, and to some extent by changes in the food of the immature larvae but not by the age or sex ratio of the parental stock, the size of puparia, selective breeding of resistant individuals or different strains of stock. Death did not occur in cold storage but during subsequent incubation at normal temperatures and at a definite stage in development near adult emergence. Temperatures below the threshold of development caused physiological disturbances that affected the longevity, oviposition, and hatchability of eggs of the adults that survived. A proposed explanation is given of the lethal effects of low temperatures based on the interrelationships of disturbances between the relative rates of development and differentiation of various ontogenetic systems.