| The predacious mite, Amblyseius barkeri, is one of important biological controlagents of Phytoseiidae. Studies on predation efficiency of different development stage ofA. barkeri to Tyrophagus putrescentiae were carried out and safety coefficient of sixinsecticides to A. barkeri was detected in lab. Furthermore, the control effect of releasingpredatory mites on population of Bemisia tabaci on tomato plants in greenhouse wasanalyzed in this paper. The main results were as follows:1. Predation efficiency of Amblyseius barkeri to Tyrophagus putrescentiaeFunction response and interfering response of A. barkeri, including female adultmite, male adult mite and nymph mite, were explored by setting five temperatures, theresults showed that the curve of function response fall in between Hollingâ…¡and Hollingâ… . Consumption of A. barkeri increased with the rise of prey density and reached stablestage lately. To some extent, different environmental temperature affected equilibrationof consumption of A. barkeri, which indicated that consumption reached stable stagewhen prey density was low level in low environmental temperature and highenvironmental temperature was in accordance with high prey density. Female adult miteof A. barkeri had greater attacking factor, shorter time of handling prey and higher dailymaximal consumption under same temperature. In general, the order of predatory ability,named a/Th, was female adult mite> nymph mite> male adult mite. The curve ofpredatory ability as a function of temperature was mouth parabolic under and reachedmaximum when in28centigrade, the value of which were10.270,6.784and3.959respectively.Average consumption of A. barkeri decreased with the rise of its density whendensity of T. putrescentiae was invariable, which indicated that it was possible tocompete or interfere each other. Interference effect gradually increased with thetemperature ascension, and the index was0.3987for16centigrade and0.4892for32centigrade.2. Safety evaluation of insecticides on Amblyseius barkeri (Phytoseiidae)In order to explore chemical controls coordinated with biological controls, toxicitytest were conducted with Bacillus thuringiensis, abamectin, imidacloprid, chlorfluazuron,deltamethrin and chlorpyrifos to A. barkeri, an important predatory natural enemy, inlaboratory in this paper. The results showed that: the overall toxicity order of several insecticides to A.barkeri was deltamethrin>chlorpyrifos>chlorfluazuron>abamectin>imidacloprid>B.t. The deltamethrin had strong toxicity to A. barkeri and LC50of it wasonly77.04mg/L; while LC50of B.t. reached17214.19mg/L. B.t and imidacloprid weresafer with releasing A.barkeri in field based on the higher safety coefficient, the valuewas8.61and4.89respectively. The results have important theoretical and practicalsignificance not only in releasing predatory mites but also in choosing suitable chemicalinsecticides in field.3. Releasing predatory mites in greenhouseThe research results based on field systematic investigation showed that the majorinsect pests on tomato plant in greenhouse were Bemisia tabaci and aphid. There wasobvious inhibition effect of A. barkeri or A. cucumeris on population of Bemisia tabaciand their controlling duration about50days, which suggested that releasing predatorymites in temporal interval and more times manner during whole development period ofplant would achieve fine control effect. There was no significant difference among twokinds of predatory mites or releasing density, but the controlling effect of A. barkeri wasslightly higher than it of A. cucumeris.Temporal niche breadths of B.tabaci of releasing predatory mites treatments werehigher than those of blank control treatment and those of chemical control treatment werelowest, which average value was only0.5818. The research results showed that there wasgreater fluctuation range of the number of population of B.tabaci and outbreak waspossible in chemical control plots. There was no significant difference of spatial nichebreadths among each treatment. |
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