Biology of the greenbug in sorghum

Abstract

The biology of the greenbug, Schizaphis graminum (Rondani, 1852) was studied using excised leaves (in laboratoty) and whole plants (in greenhouse) of the cultivars BR 503 and BR 601. In both cases the majority of individuals presented four instars. Using excised leaves, the total life cicle averaged 30.9 days with the pre-reproductive and reproductive periods averaging respectively 6.2 days and 16.8 days. The number of nymphs produced per female averaged 72.3. Using whole plants covered with a cage of transparent glass, in the greenhouse, the total life cicle was reduced to 21.2 days with the pre-reproductive and reproductive periods being 7.3 and 13.2 days, respectively. The number of nymphs produced per female was reduced to 22.1. in the experiment also using whole plants but covered with a cage made of wire frame and a fine cloth, It was observed that at 21.3 ºC, the total life cicle was 55.8 days, decreasing to 34 days at 26.2°C. The pre-reproductive period varied from 7.5 (21.3 ºC - 22.7°C) to 6.4 days (25.8 0C - 26.2°C). in addition, the reproductive period was 27.4 to 22.5 days. There was no difference in the number of produced nymphs among the female developed under the temperatures studied (21.3 °C to26.2°C). The general average was 43.6 individual per female