| Habrobracon hebetor Say(Hymenoptera: Braconidae)is a highly cosmopolitan,gregarious ecto-parasitoid of a variety of Lepidopterous larvae.In this paper,were studied the effects of different temperatures on the growth and development of H.hebetor,the effects of low temperature refrigeration on the survival rate and parasitism of H.hebetor,and the determination of the nutrient content in E.elutella larvae after being parasitized,as well as the electron microscopic observation of H.hebetor tentacle receptors,the determination of the penetration of H.hebetor on packaging materials and different mesh,and the effects of supplemental nutrition on the parasitization efficiency of H.hebetor,Horizontal and vertical diffusion of H.hebetor and horizontal diffusion of different release amounts.The results of this study provide a scientific basis for carrying out the large-scale application of H.hebetor.The results are as follows:1.The life history parameters of H.hebetor reared on Ephestia elutella(Hübner)(Lepidoptera: Phycitidae)larvae were investigated at 15,20,25,30,and 35℃.Habrobracon hebetor could complete its growth and development,and its developmental duration decreased with increasing temperature at 15,20,25,30,and 35℃.The longevity of H.hebetor adults also decreased with increasing temperature,and the longevity of females was much longer than that of males.The development threshold temperatures of H.hebetor eggs,larvae,pupae and egg-to-adult were 13.89,6.39,9.24,and 9.29℃,and the effective accumulated temperatures were 23.33,46.40,142.68,and 240.31℃·d,respectively.The total number of eggs laid by H.hebetor,the hatching rate of H.hebetor eggs and the percentage of females of offspring reached the maximum of 192.39,83.89% and 74.04% at 30℃,respectively.There was no significant difference in pupal survival rate in the temperature range of 15～35 ℃.At30℃,the preoviposition duration of H.hebetor was the shortest(0.87 d).Therefore,the optimal rearing temperature of H.hebetor was 30℃.2.In order to clarify the optimum refrigerated insect state,temperature and time of H.hebetor,the effects of different times of low temperature refrigeration on the survival rate,days of egg laying and egg production of H.hebetor were investigated.The results showed that the maximum storage days of H.hebetor eggs,larvae,pupae,females and males were 50,60,60,30 and 20 d.The maximum parasitism rates of H.hebetor eggs,larvae,pupae and adults were 18.33,34.17,48.33,92.50 and 34.17%,respectively.The maximum egg-laying rates for eggs,larvae,pupae and adults in the refrigerated initial insect state were: 195.67(20d under refrigeration at 15℃),228.67(10 d under refrigeration at 15℃),344.6(10 d under refrigeration at 15℃)and 430.67 grains(10 d under refrigeration at 10℃),respectively.The maximum egg production of pupae and adults did not differ significantly from that of the control(392.00 grains)at 30℃.The maximum egg,larval and pupae laying days were 15.67,17.00 and 16.00 d.Therefore,the optimum chilling conditions for H.hebetor were 5℃ or10℃ for adults for 10 d.3.In order to clarify the types and proportions of nutrients required for the growth and development of H.hebetor,the changes of nutrients in the body of E.elutella larvae after being parasitized by H.hebetor were investigated,and the results showed that the water content of E.elutella was 71.49,44.44 and 37.85% at 1,3 and 5 d,respectively.The protein content of E.elutella larvae decreased gradually with the increase of parasitization days;the crude fat content decreased and then increased;the alginate content increased and increased;the glucose content increased and then decreased.The nutrient contents of protein,crude fat,alginate,and glucose in the hosts were 10.30,9.09,0.13,and 0.16 g/100 g.The nutrient contents of protein,crude fat,water content,alginate,and glucose(g/100 g fresh weight)in the first fledged H.hebetor were(mean ± SE): 5.82,3.02,44.27,0.29,and 0.45.4.To study the control of H.hebetor on E.elutella,firstly,we conducted electron microscopy on H.hebetor tentacles and found that there were fewer types of H.hebetor receptors compared to other parasitoid wasps,mainly: plate receptors,scale receptors,sting receptors,hair receptors and olfactory pores.Compared with other parasitoid wasps of the family Coccinellidae,H.hebetor had no bristle receptors,bell-shaped receptors,B(?)hm’s bristles,cone-shaped receptors,or cavity cone receptors.Next,the penetration rate of H.hebetor on common packaging materials and nylon nets with different pore sizes was investigated,and it was found that H.hebetor could not penetrate non-porous materials.H.hebetor could not penetrate such as kraft paper,plastic film,woven bags and sacks,nor could it paralyze the hosts and lay eggs on the hosts through the packaging materials.For perforated materials,H.hebetor was able to pass through nylon mesh with 0.6and 0.7mm sides,and when the mesh side length was 0.7 mm,H.hebetor was able to paralyze E.elutella larvae before they passed through the nylon mesh.Therefore,nylon nets with 0.7mm mesh edge length can be used as packaging for H.hebetor.The effect of supplemental nutrition on the parasitism rate of H.hebetor was studied and it was found that glucose,sucrose and honey all increased the parasitism rate and egg production at the early stage of H.hebetor release.Glucose,sucrose and honey at 30%,10%and 20%,respectively,significantly improved the parasitization efficiency of H.hebetor in the short term;glucose,sucrose and honey at 30%,10% and 50%,respectively,had the highest total egg production within 5 days of H.hebetor parasitization,and the differences between the three concentrations were not significant;glucose,sucrose and honey at 20%,30% and40%,respectively,had the highest H.hebetor progeny emergence rate The 30% glucose solution could effectively improve the parasitization rate of H.hebetor in the early stage after release,and the effect was stable.The dispersal ability of H.hebetor was found to be stronger horizontally than vertically,and stronger downward than upward.H.hebetor first parasitized near hosts,and then gradually parasitized distant hosts.In the horizontal direction,the maximum horizontal dispersal distance of H.hebetor was 39.5 m,with a high number of distribution within 7.0-10.0 m from the release site;in the vertical direction,the maximum downward dispersal distance of H.hebetor within 1 d was 6.6 m,with no upward dispersal.The horizontal diffusion of H.hebetor with different release amounts was investigated,and it was found that the higher the number of released H.hebetor,the faster the diffusion rate.the effective number of H.hebetor staying was relatively higher at 1.6～20 m from the release point.When releasing 600 and 200 H.hebetor,the 1 d H.hebetor dwellings were less,and the2-3 d dwellings gradually increased,and the effective number of H.hebetor dwellings reached the maximum at the 3rd d H.hebetor,112.00 and 124.00 heads,respectively.After releasing200,300,600 and 1000 heads of H.hebetor for 24 h,aggregation points were formed at 4.7,13.9,15.0 and 26.0 m from the release point,respectively.From the above study,a basic process of diffusion,storage and release of H.hebetor can be established: provide E.elutella larvae into a nylon net with a side length of 0.7 mm at 30℃,place the nylon net into the hive to parasitize H.hebetor,remove the nylon net after 1～2 d,and incubate under the same conditions for about 14 d to obtain H.hebetor adults.The H.hebetor were stored at 5℃ for 10 d to accumulate the H.hebetor population.H.hebetor were fed with 30% glucose solution 1 d before release to improve the control effect of wheat moth cocoon wasps on pests.About 600 H.hebetor adults were released at 15 m intervals horizontally and 6 m intervals vertically in an environment where lepidopteran pests were present. |
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