The influence of temperature and humidity on the life-cycles of Ephestia figulilella gregson and Ephestia calidella (Guenée) (Lepidoptera: Phycitidae)

Abstract

Limiting temperatures for complete development of Cyprus stocks of Ephestia calidella and E. figulilella on semi-artificial diets at 70% r.h. were about 36°C and 15°C. The lower humidity limit for E. figulilella lay between 30% r.h. and 50% r.h., except above 36°C and below 25·5°C where it rose to between 50 and 70% r.h. The optimum temperature for survival and rate of development for both species was 30°C. For E. figulilella the optimum humidity was 70% r.h., and for E. calidella for which glycerol was added to the diet it was 90% r.h. Under the light régime of 16 hr light/8 hr dark, females of both species began to call, that is to raise their abdomens and expose their pheromone-producing glands, soon after the dark period commenced. Copulation and oviposition occurred throughout the dark period, although most eggs were laid in the first few hours of darkness. Precautions taken to reduce the risk and spread of infection by Bacillus thuringiensis included strict quarantining of freshly-collected stocks, surface sterilisation of eggs, sterilisation of food and equipment, and the use of bacteria spore-proof filter paper to seal cultures.