Abstract
"The"thermal unit" system for development was compared among four green leafhoppers, one temperate species (N. cincticeps) and three tropical species (N. virescens, N. nigropictus, N. malayanus). The developmental threshold was lowest for the egg stage of N. virescens and for the nymphal and adult stages of N. malayanus. The thermal constant was smallest for the egg and adult stages of N. nigropictus and for the nymphal stage of N. cincticeps. The hypothetical number of generations was estimated as 10 to 11, 8 to 9 and 4 in tropical, subtropical and temperate regions respectively, being similar for the four species.Nymphal development was studied under photoperiods of 8, 10, 12, 14 and 16L at 20°C. Only N. cincticeps entered diapause under 8L photophase, while the three tropical species showed slightly prolonged nymphal developmental periods under short day conditions.
