Observations on the physiology of diapause and non-diapause larvae ofBusseola fusca(Fuller) (Lep., Noctuidae)

Abstract

AbstractExperiments were done to compare respiration rate, thermal death point, weight loss and the life span of diapause and non-diapause larvae ofBusseola fusca(Fuller). The oxygen consumed by non-diapause larvae was 578–772 mm3/g/h while that by diapause larvae was 58–238 mm3/g/h. Thermal death points for both types of larvae were in the range 46·5–49·5 °C. At high and low relative humidities non-diapause larvae lost 4·4% and 16·3% of their weight, respectively, while diapause larvae lost only 1·0% and 7·0%. At 46° and 48°C the percentage weight loss by non-diapause larvae was about twice as much as that by diapause larvae. Life span was greater at a saturation deficit of 14·2–22·5 mm Hg in both types of larvae than either at 2·8–14·2 mm Hg or 22·5–28·0 mm Hg. At this range starving non-diapause larvae lived for 4·3–5·1 days and the diapause larvae for 7·7–8·7 days. The main factor enabling diapause larvae to survive adverse conditions appears to be their efficient water conservation mechanism.