Cotesia plutellae (Kurdjumov) : biology and its efficiency in biological control
1990
Jiraporn Petcharat (Prince of Songkla Univ., Songkhla (Thailand). Faculty of Natural Resources)
Biology of Cotesia plutellae (Kurdjumov) (Hymenoptera : Braconidae) a parasitoid of diamondback moth Plutella xylostella (L.) (Lepidoptera : Yponomeutidae) was studied. C. plutellae had two instars. Development of immature stages took about 12.8 days. Mean adult longevities of male and female parasitoid were 4.2 (SD = 0.9, N = 30) and 6.0 (SD = 1.5, N = 30) days respectively. Numbers of progeny per one female parasitoid at three different host densities (10, 20 and 40 host/day/cage) were 23.2 (SD = 5.3, n = 10), 27.7 (SD = 6.8, n = 10), and 26.0 (SD = 9.2, N = 10) respectively. Sex rations (male:female) of the laboratory-reared parasitoids at these different host densities were 20:1, 9.1:1 and 7.7:1 while the sex ratio of the field population was 1:1.4 (n = 223). C. plutellae showed no functional response. Means number of host killed at three host densities was not significantly increased. There was also no correlation between numbers of host killed and host densities.
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