Comparative Development ofBradysia impatiens(Diptera: Sciaridae) under Constant and Variable Temperatures

Abstract

The life stages of the sciarid fly Bradysia impatiens (Johannsen) were reared at constant temperatures of 12.8, 18.3, 23.9, 29.4, and 32.2±0.6°C, and a variable temperature regime of from 18.9 to 30.0±0.6°C. A 12-hour period of light was provided during the 24-hour day. Humidity was between 50 and 90% within the invironmental chambers and close to 100% within the individual rearing chambers. The lower and upper temperature limits for development at constant temperatures were 10°C and 32.2–35.0°C, respectively. Mean developmental period for the immature stages decreased with increasing constant temperatures until a peak temperature was reached, and then increased. Longevity increased with decreasing constant temperatures. Optimum constant temperature for the mean development of the egg, larva, pupa, and longevity of the adult at constant temperatures was 29.4, 23.9, 29.4, 12.8°C, respectively. The optimum temperature required to complete development from egg to adult was the variable temperature 18.9–30.0°C. At this temperature regime the mean developmental period was 19.2 days. At constant temperatures the mean development period ranged from 48.8 days at 12.8°C to 19.9 days at 29.4°C. Fecundity was about the same from 12.8 to 29.4°C; however, fecundity was reduced at 32.2°C. The highest temperature tested was 32.2°C and had injurious effect on eclosion of eggs, development of larvae, emergence of pupae, and longevity of the adult.