Invasive Species Compendium

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Abstract

Factors affecting the sex ratio of Leptomastix dactylopii Howard, a parasitoid of Planococcus citri (Risso).

Abstract

The male sex ratio of progeny of Leptomastix dactylopii emerging from parasitized 14-day-old Planococcus citri was 70%, and that from 42-day-old hosts was 45.5%. The sex ratio of progeny of L. dactylopii parasitizing large hosts favoured females, but small hosts favoured the males. The male sex ratio of progeny decreased as the age of the host increased, but progeny production increased as host age increased. L. dactylopii provided with 20 hosts produced progeny with the smallest male sex ratio (31%), whereas the greatest male sex ratio (45%) was obtained for those provided with 300 hosts. The male sex ratio increased with increasing host density. A high temperature (35°C) affected the male sex ratio of the progeny of L. dactylopii, but there was no effect at 15°C. No significant distinction in sex ratio was observed between the progeny produced by various densities of L. dactylopii. The total production of progeny increased with increasing density of female parasitoids. The greatest production of progeny was found at a density of 50 female parasitoids, producing 4.1 progeny per female. The sex ratio varied significantly among progeny produced by females aged 1-12 days. The production of progeny of females at ages 3 and 6 days was greater than that at 1, 9 and 12 days. No difference was found in the male sex ratio of progeny from female parasitoids reared on varied foods.