Toxicity Analysis Of Isaria To Bemisia Tabaci And It's Parasitoid Eretmocerus Hayati

Isaria fumosorosea and Isaria javanica are two common insect pathogenic fungi,which have shown promosing results for control of diamondback moth,whiteflies,and other insect pests.The objective of this study was to investigate the pathogenicity of these entomopathogenic fungi against Bemisia tabaci and to further explore the effects of entomopathogenic fungi on natural enemy Eretmocerus hayati.The results of this study will provide a reference for joint application of different biological control agents against whitefly.The main findings are as follows:?1?Toxicity analysis of Isaria fumosorosea and Isaria javanica on Bemisia tabaci.Different isolates of Isaria fumosorosea and Isaria javanica were tested for their virulence against B.tabaci.The study found that with the two entomopathogenic fungi can infect all the life stages of Bemisia tabaci,and the incerase in virulence had a dose depent effect.The Median lethal concentration(LC₅₀)of Isaria javanica and Isaria fumosorosea were 9.01×10³ and 9.74×10⁴ spores/ml,respectively.The median lethal time(LT₅₀)values were 3.051days and 4.557 days,respectively.The pathogenecity of Isaria javanica was better than Isaria fumosorosea.?2?Determination of the virulence of Isaria javanica against Eretmocerus hayati.The study found that the Flea less than that of adult's virulence of Isaria javanica,it's against the larvae and adults of Eretmocerus hayati were all greater than 1×10⁸ spores/ml,The distribution of pathogenicity the incerase in virulence had a dose depent effect.?3?Effects of Isaria javanica on Eretmocerus hayati's parasitoid potential.After treatment with Isaria javanica,the parasitism rate of Eretmocerus hayati to B.tabaci nymphs was reduced,especially the parasitism rates of nymphs at the first and second instars of B.tabaci.In the non-selective test?single age?and in case of selective test?multi-age?,the parasitism rates of Eretmocerus hayati against different instars of B.tabaci treated with Isaria javanica were in following order;2^nd>3^rd>4^th>1st nymphal.?4?Study on the combined control of pathogenic fungi and Eretmocerus hayati.Under the semi-field conditions,three treatment methods were used:single use of Eretmocerus hayati,single use of Isaria javanica spores,and joint application of Eretmocerus hayati+Isaria javanica.The results showed that the three methods mortality rates of B.tabaci respectively were 54%,55.33%,and 62.0%in two weeks.It was demonstrated that the treatment methods of Eretmocerus hayati+Isaria javanica have the best mortality rates and the control of B.tabaci can be achieved through joint application of Eretmocerus hayati and Isaria javanica.