Effects Of Cold Storage On The Fitness Of Habrobracon Hebetor(Say)(Hymenoptera:Braconidae)

Habrobracon hebetor（Say）（Hymenoptera:Braconidae）is considered to be one of most important biological control agents on lepidopterous pest and distributed all around the world.It has a good application prospect in pest biocontrol,especially for lepidoptera pests in storage due to the advantages of wide host range,high paralysis rate,high reproduction rate,long adult stage and short generation cycle.In this paper,the Ephestia elutella（Hübner）was used as the host to study the longevity and survival rate of H.hebetor adults after different cold acclimation and cold storage,and finally the optimal condition for cold acclimation were screened out.The paralysis rate,reproduction rate,preoviposition period,oviposition days and female adult longevity at different cold storage time after cold acclimation were determined.In addition,the mating under cold storage after cold acclimation with unrefrigerated and cold storage host E.elutella on the fitness of H.hebetor were systematically studied,by using the age-stage,tow-sex life table theory.The results provide some theoretical basis for extending the shelf life,mass rearing and application of the H.hebetor.The main results are as follows:1 Effects of cold storage after cold acclimation on female adult fitness of Habrobracon hebetor（Say）（Hymenoptera:Braconidae）In order to explore the optimum cold storage conditions of H.hebetor,the effects of cold acclimation,cold storage methods and cold storage time on longevity,the survival rate,paralysis rate,reproduction rate,preoviposition and oviposition days were studied at 5°C.The results showed that the life span of male and female adults（95.30and 70.27 days）of H.hebetor was significantly longer than that of control（51.27 and52.40 days）after acclimation at 15°C for 5 days and then cold storage at 5°C.And after cold storage for 30 days,the survival rate,paralysis rate and reproduction rate of the cold storage after cold acclimation was 97.83%,62.20%and 548.75 eggs,respectively,which were significantly higher than those of the direct cold storage（90.00%,43.09%and 442.13 eggs）,and there was no significant difference compared with the control.Moreover,there was no significant difference in the oviposition period between the two cold storage methods and the control,but the preoviposition period was significantly prolonged.It can be seen that the most suitable cold storage method was that the female wasps were 15°C for 5 days and then refrigerated at 5°C for 30days.2 Effects of cold storage after cold acclimation on offspring fitness of Habrobracon hebetor（Say）（Hymenoptera:Braconidae）In order to further research the effects of cold storage after cold acclimation on offspring fitness of H.hebetor.Four pairing treatments were set in the experiment,including refrigerated females and refrigerated males,unrefrigerated females and refrigerated males,refrigerated females and unrefrigerated males,as well as unrefrigerated females and unrefrigerated males（control）.The fitness of F₀ and F₁generations of H.hebetor after different pairing treatments was evaluated according to the theory of age-stage,tow-sex life table.The results showed that cold storage after cold acclimation had no significant effect on the mean reproduction rate and oviposition days of F₀ generation,as well as the adult life span and oviposition days of F₁ generation.Especially in the pairing treatment of mating between cold storage females and unrefrigerated males,the developmental time（10.24 days）of F₁generation of H.hebetor was the shortest,the survival rate（61.43%）and the proportion of females（0.41）were the highest.In addition,the population parameters（intrinsic rate of increase,r;finite rate of increase growth rate,λ）and paralysis rate parameters（net paralysis rate,C₀;stable paralysis rate,ψ;and finite paralysis rate,ω）of this treatment were higher than those of the other three treatments.Similarly,the population growth potential（2,540,948,887 individuals）and paralytic potential（536,756,152 individuals）of this condition were the highest.The results showed that the cold stored female wasps had high feasibility and could be used for mass storage and application of H.hebetor.3 Effects of cold storage of Ephestia elutella（Hübner）（Lepidoptera:Pyralidae）on the fitness of Habrobracon hebetor（Say）（Hymenoptera:Braconidae）In order to evaluate the effects of E.elutella stored at 5℃for different time（0,15,30 and 60 days）on the fitness of H.hebetor.The age-stage,two-sex life table was used to evaluate the developmental duration,survival rate,fecundity,population parameters and paralysis rate of H.hebetor on E.elutella at different cold storage times.The results showed that on the E.elutella stored for 30 days,the pre-adult duration was shorter.But the survival rate,mean reproduction rate and the proportion of females were the highest.Population parameters（intrinsic rate of increase,r;finite rate of increase,λ;and net reproduction rate,R₀）were better than those of the other three treatments.Paralysis rate parameters（net paralysis rate,C₀;stable paralysis rate,ψ;and finite paralysis rate,ω）were not significantly different in all treatments,but transformation rate（0.3612）was significantly higher than 0 and 60 days of cold storage.By predicted of population growth potential and paralysis potential of the parasitoid on the four treated host of E.elutella within 60 days,which also indicated that the parasitoid had the highest population growth potential（3,587,837,818 individuals）and paralysis potential（539,670,155 individuals）on the host stored for 30 days.The results showed that H.hebetor could complete the whole generation cycle on E.elutella within60 days of cold storage,and the host stored for 30 days was most beneficial to the mass rearing of H.hebetor.