Construction Of A Combined Control System Against Bmisia Tobaci By Nesidiocoris Tenuis And Eretmocerus Hayati

Bmisia tobaci,with fast reproduction rate and broad host plant range,is an important agricultural invasive pest in China.It has caused seriously loses in agriculture and gardening.Eretmocerus hayati is a parasitoid of B.tabaci and showed impressive control potential for B.tabaci,but the control efficacies between populations are not always stable.Therefore,in order to improve the biodiversity of the biological control system and the control effect on B.tabaci,it is proposed to introduce the predatory natural enemy,Nesidiocoris tenuis,into the biological control system of E.hayati against B.tabaci.In this study,on the basis that the biological parameters and control efficacy of E.hayati had been clarified in the previous studies,the biological parameters of the population of N.tenuis and combined control efficacy of E.hayati and N.tenuis was evaluated,so as to provide a theoretical basis for the establishment of an efficient and sustainable green biological control system for B.tabaci.The main results and conclusions are as follows.1.The fitness of N.tenius on cotton was determined through the establishment of the age-stage two-sex life table.The developmental durations for eggs,nymphs and adults of female were8.1±0.3d,20.3±0.8d and 12.1±2.8d,respectively,and the developmental durations for eggs,nymphs and adults of male were 8.1±0.6d,19.2±0.5d and 15.2±3.3d,respectively.The oviposition period of female adults was 2.33 days,and no.of eggs laid per female was 2.79.The population intrinsic rate of increase（r_m）,net reproductive rate（R₀）,finite rate of increase（λ）and average generation time（T）of N.tenius were-0.0146d^-1,0.5521progeny/individual,0.9855d^-1and 40.68 days,respectively.2.The functional responses and control effects of female,male and 5^thinstar nymph of N.tenius on B.tabaci nymphs were clarified.Results showed the functional responses of female,male and 5^thinstar nymphs of N.tenius to B.tabaci first to fourth instar nymphs were all type II.When the first instar B.tabaci nymphs were provided,there was no significant difference in the searching rate and handling time among female,male and 5^thinstar nymphs of N.tenuis.When the second to fourth instars B.tabaci nymphs were provided,there was no significantly difference in the searching rate among female,male and 5^thinstar nymphs of N.tenius,but the handling time for male adults to each instar B.tabaci nymph were significantly longer than that for 5^thinstar nymphs and female.Against the same instar but different densities of B.tabaci nymphs,the number of B.tabaci killed by female,male and 5^thnymphs of N.tenius were significant different.Against the same density but different instars of B.tabaci nymphs,the number of B.tabaci killed by female,male and 5^thnymphs of N.tenius decreased significantly with the increase of B.tabaci nymph instars.Among the three states of N.tenius,the consumption rate of the 5^thinstar nymph of N.tenius were generally higher when supplied with the younger nymph of B.tabaci,while that of the N.tenius females were higher when supplied with the older nymph of B.tabaci.3.The combined control efficacy of N.tenius and E.hayati against B.tabaci nymphs was investigated.No.of the 2^ndand 3^rdinstar nymphs of B.tabaci killed by the combined release of the female of N.tenius and E.hayati was higher than that in the single release of N.tenius female.The killing rates of B.tabaci by N.tenius female in single release or combined release were higher than 60%.Especially,the killing rate of B.tabaci 2^ndinstar nymphs in combined release was up to 80%.The result indicated that N.tenius showed a strong control efficiency against B.tabaci on cotton,and the combined release of N.tenius and E.hayati is more effective than N.tenius released alone.