| The egg parasitoids,Trichogramma spp.(Hymenoptera: Trichogrammatidae),have been widely used as the biological control agent against multiple lepidopteran pest species in agriculture and forestry.In the case of application of Trichogramma using inundative release method for a fast control of pests,massive Trichogramma production should be provided in a short time through the mass-rearing system.Compared with bisexual strains of Trichogramma wasps,thelytokous strains of Trichogramma wasps are often viewed as the superior biological control agents for some advantages:(1)a higher reproductive efficacy as all offsprings are females;(2)the reduction of production cost in mass rearing because the “wastage” of host resource for the males is not necessary;(3)easier population colonization in fields because the released females could produce female offsprings without mating.In order to improve the rearing techniques of thelytokous Trichogramma production,we investigate the suitable host egg of Antheraea pernyi strains,optimal clutch size reared on A.pernyi eggs,the parental development temperature for the induction and lift of offspring diapause,the parasitic efficacy of thelytokous T.dendrolimi.The results would supply the reference for the improvement of the mass rearing procedures of T.dendrolimi production based on the alternative host,A.pernyi eggs.The results showed:1.We compared the differences of brood size,female number per host egg,and body size of offspring females which reared among seven strains of A.pernyi eggs,and found thelytokous offspring wasps emerged from “Kang Da” strains of A.pernyi eggs all performed bigger body size(0.2072±0.107 mm),larger brood size(119.93±2.73)and female number per host egg(119.93±2.73),where bisexual offspring wasps emerged from “Qing Da” and “998” strains of A.pernyi eggs all performed biger body size(NEE: 0.2711±0.015 mm;QD: 0.2796±0.0111 mm),larger brood size(NEE: 77.00±3.10;QD: 85.93±2.39)and female number per host egg(NEE: 64.00±2.82;QD: 72.40±2.19).Besides,the body sizes of thelytokous offspring were significant higher than bisexual offspring regardless of A.pernyi strains.We detect the nutrition components of the eggs of different A.pernyi strains,and found the saccharide contents in the eggs of A.Pernyi strains “Kang Da” and “988” were significantly higher than those of other five A.pernyi strains,where the protein contentsin the eggs of A.pernyi strain “Kang Da” and “988” were significantly lower than those of other A.pernyi strains except “9906”.The triglyceride content of “Qing Da” was the highest,where those of “988”,“Gao Xin”,“Te Da”,and “Kang Da”were at medium and all significantly higher than those of “9906” and “Kang Da”.The results showed the fitness of Tdw+ offspring maybe positively correlated with saccharides contents and negatively correlated with protein content.The fitness of Td offspring may be positively correlated with the content of saccharides and protein.2.We provide an accurate standard of the optimal clutchsize for the quality control of Wolbachia-infected thelytokous T.dendrolimi production.When the number of clutch size was 57.14/egg,52.93/egg,56.80/egg,70.10/egg,or 53.64/egg,the emergence rate,body size(hind tibiae length),individual fecundity,total fecundity,and adult lifespan of female Tdw+ strain reached the highest.Compared with bisexual T.dendrolimi offspring,their infected thelytokous counterpart showed reduced life span,prolonged development time but had higher emergence rate.3.When maternal temperature was at 17?,the diapause rates of the Tdw+ strain(30 d: 98.97%;45d: 99.54%;60 d: 95.27%)were significantly higher than Td strain(30 d: 84.68%;45d: 83.44%;60 d: 52.17%),respectively.When maternal temperature was at 25?,the diapause rates of the Tdw+ strain(30 d: 93.91%;45d: 95.72%;60 d: 98.56%)were significantly higher than the Td strain(30 d: 68.15%;45d: 79.97%;60 d: 45.95%),respectively.When maternal temperature was at 17?,the diapause rates of the Tdw+strain were significantly higher than those when maternal temperature was at 25?,but the difference was insignificant in Td strain.When maternal temperature was 17?,the diapause lift rate of Tdw+ strain were 81.53%,82.24%,90.78%,90.56%,and 93.05% for 50 d,60 d,70 d,80 d and 90 d storage time,respectively.The diapause lift rates of the Td strain were 78.93%,84.59%,86.6%,94.13%,and 92.86% for 50 d,60 d,70 d,80 d,and 90 d,respectively.4.Our results showed that Wolbachia-infected thelytokous females performed a declined parasitic capacity when they compared with their uninfected bisexual counterparts in intra-strain cohorts.The results also showed infected females performed a higher probability of superparasitism.According to the present results,mixed release of both strains may bring positive effects on the control of pest,as more host eggs would be parasitized due to the different parasitic behavior mode of these two strains;the male proportion of bisexual offspring was significantly higher than that when only bisexual strain supplied;the male proportion of bisexual offspring increased with wasp density in Inter-Td group. |
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