Department of Zoology and Wildlife Conservation

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Browsing Department of Zoology and Wildlife Conservation by Subject "A. gossypii"

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    Comparative Biology of Mallada Desjardinsi (Navas) and Chrysoperla Congrua (Walker) (Neuroptera: Chrysopidae), Predators of Helicoverpa Armigera (Hubner) (Lepidoptera: Noctuidae) and Aphis Gossypii (Glover) (Homoptera: Aphididae) On Cotton in Eastern Tanzania
    (Taylor and Francis, 1995) Kabissa, Joe C.B.; Kayumbo, H. Y.; Yarro, Jacob G.
    The developmental biology of Mallada desjardinsi (Navas) and Chrysoperla congrua (Walker) on the American bollworm, Helicoverpa armigera and the cotton aphid, Aphis gossypii was studied in the laboratory at 28–32°C. Total larva! periods of M. desjardinsi and C. congrua on H. armigera eggs were 14.4 and 14.8 days respectively. However, when reared on A. gossypii larval periods of M. desjardinsi and C. congrua were 14.9 and 13.5 days respectively. When reared on H. armigera 52.9% and 25% respectively of third instars of M. desjardinsis and C. congrua sp. died before pupation. However, when reared on A. gossypii 82.6% and 46.9% respectively of third instars of M. desjardinsi and C. congrua died before pupation. Thus, H. armigera eggs and A. gossypii nymphs were both adequate but not optimal diets for chrysopid larval development. The number of prey consumed by M. desjardinsi and C. congrua increased with instar. Total larval consumption of H. armigera by M. desjardinsi and C. congrua was determined to be 135.5 and 169.8 eggs respectively. However, total larval consumption of A. gossypii by M. desjardinsi and C. congrua was found to be 189.0 and 171.8 nymphs respectively. Because of its longer larval period, and higher consumption of A. gossypii, M. desjardinsi would be better suited for use against A. gossypii than C. congrua. In contrast, C. congrua whose consumption of H. armigera was higher than that of M. desjardinsi although their larval periods were similar, would appear promising for control of H. armigera.
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    Seasonal Abundance of Chrysopids (Neuroptera: Chrysopidae) Preying on Helicoverpa Armigera (Hubner) (Lepidoptera: Noctuidae) and Aphis Gossypii (Glover) (Homoptera: Aphididae) on Cotton in Eastern Tanzania
    (Elsevier, 1996) Kabissa, Joe C. B.; Kayumbo, H. Y.; Yarro, Jacob G.
    The occurrence of chrysopids on cotton in relation to Helicoverpa armigera and Aphis gossypii was studied between 1988 and 1991. By the 8th week after germination predators and their prey were already established on the crop. Among the chrysopid species observed on cotton, only Mallada desjardinsi (Navas) and Chrysoperla sp. occurred on cotton when both H. armigera and A. gossypii were present. Chrysopids and A. gossypii were most abundant on cotton between the 12th and 15th weeks after germination. However, peak abundance of eggs and larvae of H. armigera on cotton occurred earlier between the 8th and 13th weeks. Parasitism in populations of field collected larval, pupal and imaginal chrysopids was noted. Activity of adult H. armigera and chrysopids monitored by light traps showed two peaks of abundance coinciding with short and long rains. Prospects of manipulating chrysopids for biological control of H. armigera and A. gossypii are discussed.