Study On Parasitic Selection And Adaptability Of Six Species Of Trichogramma To Main Agricultural Pests

There were significant differences in the parasitic selection and the adaptability of different Trichogramma species to eggs of different hosts,while the same Trichogramma species also have significant differences for the host egg age selection.Therefore,the suitability of "pest-parasitoids" and " parasitoids-egg age" has become a matter of great concern to domestic and foreign biological control workers.In this study,six Trichogramma species,including five native Trichogramma species,Trichogramma dendrolimi,Trichogramma ostriniae,Trichogramma leucaniae,Trichogramma chilonisand Trichogramma japonicun,which are trapped in the wild and Trichogramma embryophagum that is introduced from other localities or foreign countries as the research objects.By measuring the biological parameters of the six Trichogramma species that parasitized in five different kinds of pest eggs,we evaluated the biocontrol potential of these several Trichogramma on the common pests and to screen out the advantage Trichogramma species to control target pests.In this study,we aim to provide new ideas for the biological control of the efficient use of wasps,and we also provide theoretical basis for the release and application of the parasitoids in the field.The main results are as follows:1.Host selection and adaptability of five native species of Trichogramma on the corn borer eggs.The T.dendrolimi prefer parasitizing in fresh corn borer eggs that spawning in 24 hours,the parasitism rate of 0 day age egg was as high as 73.5%,but the parasitic rate decreased sharply of 1 day age egg,which was as low as 10%.The T.ostriniae possess strong ability of parasitism.Our research showed that there were strong ability of parasitism on the fresh 0 day old eggs,1 day old eggs and 2 day old eggs.However,the parasitism rate decreased significantly in 3 day old egg.As for T.chilonis,T.japonicun,and T.leucaniae,the parasitic effects were bad for the three species and the parasitism rate were less than 15% at all for the 0-3 days old eggs.Therefore,the dominant species of T.ostriniae can be used to control corn borer.2.Host selection and adaptability of Trichogramma on striped rice borer eggs.The parasitic effects of T.japonicum on 0-day-old eggs were better,it parasitic rate as high as 80% or more,while the 2-day-old eggs,the parasitic rate of eggs decreased,and there was significant difference with 0 day old eggs.There was no significant difference in the parasitism rate about T.chilonis and T.dendrolimi at each old eggs.The parasitism rate of T.embryophagum was higher than 50% for each old eggs,and showed better parasitic effects.There was no significant difference of parasitism rate of T.leucaniae at 0 and 2 day old eggs,but the parasitism rate was low.On the 0 day old eggs,The parasitism rate of T.japonicum were the highest,followed by T.embryophagum,The parasitism rate of T.japonicum was significantly higher than that of the other three Trichogramma species;On the 2-day-old eggs,The parasitism rate of T.japonicum were the highest,followed by T.chilonis,however,there was no difference in the parasitism rate between T.chilonis and T.dendrolimi,T.leucaniae,T.japonicum.On 4 day old eggs,the parasitism rate of T.embryophagum was significantly higher than that of T.dendrolimi and T.leucaniae.In general,T.japonicum and T.embryophagum can be used to control striped rice borer as a dominant species of Trichogramma.T.chilonis and T.dendrolimi also show better control potential.As the T.embryophagum is the introduction of alien species,whether it can be used to control striped rice borer as a dominant species at Jilin Province need to further study.3.Host selection and adaptability of five native species of Trichogramma on oriental armyworm eggs.The parasitism rate of T.dendrolimi in the 0 day old eggs was significantly higher than that in 2 and 3 days old eggs.However,there was no significant difference of the parasitism rate among 1,2 and 3 days old eggs,and the parasitic ability was even strong of the 3 days old eggs of oriental armyworm,which can reach to 30%.There were certain parasitic effects of T.chilonis in 0-2 day old eggs and no significant difference can be found,furthermore,the parasitic ability was decreased significantly on 3 day old eggs.However,there were good preference of parasitism to fresh eggs of T.ostriniae,T.leucaniae and T.japonicun.So T.dendrolimi can be used to control the oriental armyworm of dominant species.4.Host selection and adaptability of five native species of Trichogramma on diamondback moth eggs.T.dendrolimi prefer parasitizing in fresh diamondback moth eggs,and the parasitism rate was about 60% of the 0-day-old eggs.However,the parasitism rate was decreasing sharply on the 1 day old eggs.But no significant difference was found of the parasitism rate between 0-day-old eggs and 1-day-old eggs.The parasitism rate of T.ostriniae was higher than that of T.chilonis,and wide range difference of parasitism rate were found in different age of eggs.There were higher parasitism rate were found in the 0 and 1 day old eggs(T.ostriniae,0-day-old eggs: 82.4%,1-day-old eggs: 54.1%;T.chilonis,0-day-old eggs: 85.0%,1-day-old eggs: 32.2%).The T.japonicum prefer parasitizing 0 day old eggs and a sharply decrease of the parasitism rate can be found of the 1 day-old eggs,and the parasitism rate was even lower in 2-day-old eggs.When come to the T.leucaniae,the parasitism rate in the 0,1 and 2 days old eggs were not good,and the parasitism rates were less than 15% at all.Therefore,T.ostriniae and T.chilonis can be used to control diamondback moth as dominant species.5.Host selection and adaptability of five native species of Trichogramma on beet armyworm eggs.Although each age of beet armyworm eggs have been dealt with parasitism,but the results showed that only the 0 day old eggs of Spodoptera exigua were parasitized by five species of Trichogramma,and the parasitic effect was not good parasitism rate were below 10% at all.Among the five Trichogramma,the parasitism rate of T.japonicum was the highest(about 10%).However,the parasitism rate of the other four Trichogramma species were below 5%,and there is no significant difference.In this study,we compared the biological parameters of six Trichogramma species on different pests eggs.The results show that,the dominant species of T.ostriniae can be used to control corn borer and diamondback moth;the T.chilonis can be used to control diamondback moth and striped rice borer as a dominant species of Trichogramma;T.dendrolimi can be used to control oriental armyworm as a dominant species of Trichogramma;T.embryophagum and T.japonicum can be used to control striped rice borer as dominant species of Trichogramma.