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Sudan Journal of Agricultural Research

Preliminary biological observations on Microbracon beneficentior in the Gezira State
 

R.M. Khafagi¹
 

Abstract:
 

The parasitoid, Microbracon beneficentior Vier. was reared for several generations in the laboratory on larvae of three insects, namely the dura stem-borer, Sesamia cretica (Lederer.); the spiny bollworm, Earias insulana (Boisduval) and the African bollworm, Helicoverpa armigera (Hubner) in order to study some biological parameters. Second instar larvae of these insects, offered separately or together to the female parasitoid, were not accepted for parasitization. However, the percentage of the larvae parasitized increased when older larvae were placed, i.e third and fourth instar larvae.Fifth instar larvae, were less preferred. Although sixth instar larvae of  H. armigera were stung by the female parasitoid, no larvae of the parasitoid issued from them. In all treatments, increase in the size of  the host decreased the period of development of the parasitoid, increased the size of the parasitoid and raised the fecundity of females. The progeny produced by unmated females of the parasitoid were all males, while those produced by mated females were a mixture of males and females. The sex ratio of the progeny of mated females was generally male biased. In all treatments the percent of  female progeny bred from 4th instar larvae, was greater than in those bred from the other instars tested.

Keywords:

Sudan Journal of Agricultural Research Vol. 3 (2000) PP. 49-57