Functional response of Stethorus gilvifrons (Col.: Coccinellidae) to different densities of Eutetranychus orientalis (Acari: Tetranychidae) in laboratory
2011
P. Shishehbor | Z. Imani
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 24 hours with different prey densities at 30ºC and a photoperiod of 14: 10 (L: D). The number of prey consumed by the predator was checked after 24 hours. Each larval stage of S. gilvifrons showed a type II functional response when 88 eggs out of 120 eggs were consumed by the fourth-instar larva. Based on the random predator equation, the estimated attack rates of S. gilvifrons were 0.065, 0.089, 0.143, 0.125 and 0.046 per hour while the estimated handling times stood at 0.141, 0.166, 0.150, 0.134 and 0.082 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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