Charles Adarkwah, Carmen Büttner, Matthias Schöller, Christoph Reichmuth:
Host Finding Ability of Lariophagus distinguendus (Förster) (Hymenoptera: Pteromalidae) in Bagged Maize: A Potential Biocontrol Agent of the Maize Weevil Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae)

CHARLES ADARKWAH¹, CARMEN BÜTTNER¹, MATTHIAS SCHÖLLER², CHRISTOPH REICHMUTH^3
1Humboldt-Universität zu Berlin, Department for Horticultural Sciences, Germany
²Julius Kühn Institute, Federal Research Centre for Cultivated Plants, Institute for Ecological Chemistry, Germany
³Federal Biological Research Centre for Agriculture and Forestry (BBA), Germany

The maize weevil, Sitophilus zeamais is a major pest of durable stored cereals pest of maize in sub-Saharan Africa, where it is causing considerable economic losses of the crop. The parasitic wasp, Lariophagus distinguendus is a synovigenic, solitary larval and pupal ectoparasitoid of several beetle species that infest stored goods. The parasitoid egg is laid into the infested grain beside the beetle larva. The host location ability seems to be highly developed and the female parasitoid is able to discriminate between healthy and infested grains. The potential of using L. distinguendus for the biological control of S. zeamais was assessed in maize stored in jute bags and bulk grain by investigating its host finding and its ability to penetrate the grain mass to parasitize its host. L. distinguendus penetrated and parasitized S. zeamais located in the jute bags, and the storage cylinders at various depths. Over 50% adult L. distinguendus released into the chamber entered the jute bags to parasitize S. zeamais. Thus, L. distinguendus was able to find its host within the jute bags and storage cylinders containing S. zeamais infested maize kernels and produced F1 offsprings. The parasitic wasps also significantly reduced the emergence of S. zeamais in stored jute bag and in bulk maize. L. distinguendus searched and located its host in the jute bags and storage cylinders containing infested maize kernels placed in the wire mesh cages and produced F1 progeny. This suggests possible practical utilisation of L. distinguendus for the control of S. zeamais in bagged stored maize.

Keywords: Biological control, jute bag, Lariophagus distinguendus, Sitophilus zeamais

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Contact Address: Charles Adarkwah, Humboldt-Universität zu Berlin, Department for Horticultural SciencesLentzeallee 55, 14195 Berlin, Germany, e-mail: lesadarkyahoo.com