Some parasitoids of lepidopterous stem borer pests on maize in southern Ghana

Abstract

Studies were carried out in Southern Ghana (7 Administrative Regions) to assess the diversity and level of parasitism of some parasitoid species of stem borer pests of maize. Two surveys, one in the major season and the other in the minor season were carried out in seven regions in Southern Ghana in 1996. Maize fields were sampled for stem borers. Parasitoids collected were identified up to species level. The rate of parasitism of the stem borers by the parasitoids was also determined. The main pests collected were: Eldana saccharina walker, Sesamia spp., Busseola fusca (Fuller), and Chilo aleniellus (Strand). Parasitism was recorded in more fields in the minor season than in the major season. In both seasons, percentage parasitism ranged between 0 and 100%. Syzeuctus sp was found parasitizing E. saccharina. Other parasitoids reared from stem borers were Enicospilus (Ophion) sp, Dolichogenidia sp. and Aphanogmus fijiensis. Syzeuctus sp. was the most abundant and most distributed parasitoid species followed by S. parasitica. Hence, the two species (Syzeuctus sp. and S. parasitica) should be mass produced and released into maize fields to augment the number of parasitoids in the field in integrated pest management scheme, when pest population is high. Key words: Stem borer, parasitoid, Eldana saccharina, hyperparasitism, gregarious.