Much of the data on pesticides and biocontrols is based on acute LC50. However acute LC50 data may not be very valuable for determining the compatibility of pesticides and biocontrols. A thorough examination of sublethal effects is necessary to determine compatibility. We used a life table approach to tease apart sublethal effects.
Laboratory experiments were conducted to examine the effect of Pymetrozine and Sylgard 309, a surfactant on life table parameters of the aphid parasitoid, Diaretiella rapae offered Brevicoryne brassicae hosts. Newly emerged male-female parasitoid pairs were offered 100 hosts daily until death of female. Parasitoids were fed honey water and experiments were placed in an environmental chamber set at 25°C and 50% relative humidity. Emerged progeny were counted and sexed. Both adult and mummy stage of Diaretiella rapae were tested. Exposure of parasitoids to Pymetrozine and Sylgard 309 led to a reduction in the net replacement rate, Ro and the intrinsic rate of increase, rm. There was a shift in stable age distribution from young to an old population, and the mean generation time was not affected.
Species 1: Homoptera Aphididae Brevicoryne brassicae (cabbage aphid)
Species 2: Hymenoptera Aphidiidae Diaretiella rapae (cabbage aphid parasitoid)
Keywords: life table, pymetrozine
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