Adaptability To Temperature Of Rhynchophorus Ferrugineus(Olivier)

Red palm weevil(RPW),Rhynchophorus ferrugineus(Oliver)(Coleoptera:Curculionidae)is an invasive pest which often infests palm trees and has caused great economic losses for palm-related industries in south of China since it was first found in Hainan Province in 1998.In this study,firstly,survival,development and reproduction of RPW that are reared in the different designated temperatures were recorded.Secondly,cold-and heat-tolerance of RPW larva with or without acclamation treatment were tested.Third,the expression levels of heat stock protein genes in PRW larvae after acclamation treatment were measured.The goal of this study was to investigate(1)the effects of temperature on the RPW population dynamic;(2)whether thermal tolerance of RPW was plastic and crossed and(3)what is the function of hsps in the mechanism of cold-and heat-tolerance.Our study will provide basic information about preventing and controlling RPW and lay a foundation for mechanism study about thermal tolerance of insects.Main results were listed as below:1.The optimal temperature zone for RPW is 27-30,and it could not survive under conditions of 15? or 18?.Population parameters were the largest at 27?.Intrinsic rate of increase(r),finite rate of increase(?),net reproductive rate(R0),mean generation time(T)were 0.0152 d-1,1.0153 d-1,16.67 offspring/individual,183.3 d at 27?,respectively.2.Mortalities of the treated groups(40? for 0.5,1,1.5 and 2 h)after heat stress were significantly lower than that in the control group.Similarly,the mortality of control group under cold stress was also markedly higher than that in the treated groups.47.63%of the individuals after being acclimated(0? for 3 h)died under heat stress,which was significantly lower than that of control groups(74.04%).Similar results were observed in the groups that being acclimated(40? for 1.5 h)were exposed under cold stress.Results demonstrated that high and low temperature acclimation could enhance their resistance to temperature stress and the acclimation of low temperature elevated their resistance to heat stress and vice versa.Strikingly,the effect brought by cold acclimation on thermal tolerance was much better than that from heat acclimation.3.Significant variations in the transcript quantity of RPW larva hsp70-1,hsp70-2,hsp70-3 and hsp90 were determined after it has been exposed to 40? for 1.5 h or 0? for 3 h.However,no changes were detected in the expression level of hsp70-1,hsp70-3 and hsp90 gene after the exposure of nonlethal-low temperature.But the expression level of hsp70-2 was upregulated 4 times than the control.Compared with the above results,all the expression level of hsp70-1,hsp70-2,hsp70-3 and hsp90 gene were markedly upregulated after the exposure to nonlethal-high temperature.These results suggested that hsp genes might play vital roles in the improvement of thermal tolerance for RPW larvae.