THE INFLUENCE OF TEMPERATURE ON THE POPULATION INCREASE OF MYZUS PERSICAE AND LIPAPHIS ERYSIMI

The development,survival and reproduction of anholocylic virginoparae of Myzus persicae (Sulzer) and Lipaphis erysimi (Kaltenbach) (Homoptera:Aphididae),reared on Brassies chin-ensis,were observed under a series of constant and natural temperature regimes.The results are summarized as follows.(1) Temperature exerts direct influence on the development rates (as well as the wing,formation of M.persicae),life-span and survivorship,fecundity and reproductive rates of the two aphids.(2) The spans of temperature range within which survival and reproduction are possible are more or less similar for the two aphids,and under con-.stant conditions the range from low to high limits is about 23 C.However,the actual temperature scale for M.persicae is some 3-4℃ lower than that for L.erysimi.(3) Under relatively low temperatures,the development and survival rates during immature stages,fecundity and reproductive rates of M.persicae are all higher than those of L.persicae,while under relatively high temperatures the reverse is ttue.(4) The relationships between the intrinsic rates of increase and temperature are of parabolic type'with the highest value occurring at relatively high temperatures.Within the range of 16℃ to 21℃ the intrinsic rates of increase are similar for the two aphids;at temperatures below 16℃,the rates of M.persicae are higher than those of L.erysimi,while at temperatures above 24℃the rates of L.erysimi are higher.(5) The two aphids can survive considerably lower thermal levels under natural than under constant temperature conditions.