Abstract

Laboratory study was carried out to investigate the efficacy of hymenopteran parasitoids, (Dinarmus basalis and Choetospila elegans) parasitization of Callosobruchus maculatus on cowpea (Vigna unguiculata) seeds in the Department of Crop Science, University of Calabar, Nigeria. Treatments were the inoculation of D. basalis (sole), C. elegans (sole), a mixture of D. basalis and C. elegans into infested cowpea seeds and the control which received no parasitoids. The introduction of parasitoids was repeated at 3 d interval, and all treatments were replicated 3 times. Result indicated that early introduction of the parasitoids caused significantly (P ? 0.05) higher mortality of C.maculatus than late introduction. Mix culture of both parasitoids was significantly more efficacious than sole culture. The emergence of each parasitoid and the mortality of C. maculatus in sole culture showed a highly significant (P ? 0.01) positive relationship (r = 0.487) between C. maculatus and D. basalis but non-significant (P ? 0.05) though positive association (r = 0.289) with C. elegans. A multiple regression analysis between C. maculatus mortality and the emergence of the two parasitoids in mix culture also indicated a highly positive significant (P ? 0.01) relationship (R = 0.751, R² = 0.564). Pearson Correlation analysis also showed a significant (P ? 0.05) positive association (r = 0.464, and 0.401) between C. maculatus mortality and emergence of C. elegans and D. basalis in mix culture, respectively. However, a non significant (P ? 0.05) negative relationship (r = -0.336) was observed between the two parasitoids in their emergence in mix culture, but D. basalis contributed more to the mortality of C. maculatus than C. elegans. Data from this study showed that D. basalis and C. elegans have potentials to be deployed as biological control entities in the management of C. maculatus as a part of the integrated pest management strategies of storage pests in the tropics.

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