Functional response of Stethorus gilvifrons (Col.: Coccinellidae) to different densities of Eutetranychus orientalis (Acari: Tetranychidae) in laboratory

The stage specific functional response of the acarophagous ladybird beetle Stethorus gilvifrons Mulsant to varying densities of citrus brown mite Eutetranychus orientalis (Klein) eggs was examined in a simplified castor bean leaf arena under laboratory conditions. All stages of S. gilvifrons were individually isolated for ۲۴ hours with different prey densities at ۳۰ºC and a photoperiod of ۱۴: ۱۰ (L: D). The number of prey consumed by the predator was checked after ۲۴ hours. Each larval stage of S. gilvifrons showed a type II functional response when ۸۸ eggs out of ۱۲۰ eggs were consumed by the fourth-instar larva. Based on the random predator equation, the estimated attack rates of S. gilvifrons were ۰.۰۶۵, ۰.۰۸۹, ۰.۱۴۳, ۰.۱۲۵ and ۰.۰۴۶ per hour while the estimated handling times stood at ۰.۱۴۱, ۰.۱۶۶, ۰.۱۵۰, ۰.۱۳۴ and ۰.۰۸۲ per hour for the first, second, third and fourth instar as well as the adult female respectively. The species S. gilvifrons showed to be an effective predator on E. orientalis under controlled conditions. The results suggest that the simultaneous use of the both fourth-instar larvae and adult females of the acarophagous ladybird beetle could increase the rate of predation in the field.

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واکنش تابعی ، Stethorus gilvifrons ، Eutetranychus orientalis ، ایران