Effect Of Extreme Temperatures On Survival, Development And Growth Of Hyphantria Cunea

Hyphantria cunea is one kind of international and domestic plant quarantine object. It is omnivorous large amount of propagation and having a good adaptability, Hyphantria cunea can damage plants for a long time and spread throw many ways. In order to master the effect of extreme temperature on the moths, predict its quantity and dynamics of population growth, the life history in Weifang, the effect of extreme temperatures was studied in the paper.Life history in Weifang The life history table was plaited in Weifang and found that the moths finished three generations, only a little individual over winter by larvae. The first generations grow in order while the second and the third generation overlapped . the west area appeared earlier than the east area and the north area earlier than the south area in Weifang.Life habit of Hyphantria cunea The key period of metamorphosis such as emergence and hatching focused on the same time in one day. We found that the hatching time is different for the same eggs mass. Some larvae enter the second instars while some just emerged only.Effect of low temperatures on over wintering pupae The survival rate reduces with the prolonging of the treatment time under low temperatures. Almost of the pupae can not survive for 30 hours under–10°C and 3 hours under–15°C as well as 25 minutes under–20°C. The pupae survival rate (58.7%)is lower than the pupae collected from the field(64.2% )under -10°C for 5 hours..Effect of 0°C low temperature pulse on pupae 0°C low temperatures treatment can improve the survival rate of over wintering pupae. The survival rate boosted with prolong of treatment time of 0°C low temperatures.After the time exceed 150 minutes under 0°C, the survival rate increased not significantly.Effect of high temperatures on the Hyphantria cunea The tolerance capability is strong of Hyphantria cunea. The hatching rate of the eggs, the survival rate of the larvae and emergence rate of the pupae and the life length of the adults descended with the elevation of the high temperatures. High temperatures pulse can reduce the survival rate of the hatched eggs.The effect on different results for different instars larvae showed the larger instars larvae survive more than the smaller instars larvae under the same high temperature.