Biology and life table of greenbug, Schizaphis graminum Rondani (Hom., Aphididae) on broom corn,Sorghum cernuum

Schizaphis graminum is one of the most important pests of broom corn in early season. Biology and life table parameters of this aphid was investigated in laboratory at 5 ± ˚C, 50-60% relative humidity, and a photoperiod of 6:8 (L:D) hours. The experiment was carried out by rearing 50 four hour-old aphid nymphs in leaf cages and their mortality and ecdysis was recorded daily. The results indicated short development time of different nymph instars, so that they completed its development in 6.98 days. Prelarviposition period was very short and mean generation time was 7.48 days. Mean longevity of the aphid was 35.4 days. Survival curve of S. graminum on broom corn was determined as type І. There was not observed any mortality in nymphal development period. Mortality rate was also very low in young adult stage. Maximum death rate (0.6) occurred in 33-old age and life expectancy of the aphid was estimated 34.74 days in st instar nymph stage and decreased gradually in a constant rate. The results of this study revealed relatively high longevity and slow mortality trend in aphid population.