Description of a new species of <i>Orseolia</i> (Diptera: Cecidomyiidae) from <i>Paspalum</i> in West Africa, with notes on its parasitoids, ecology and relevance to natural biological control of the African rice gall midge, <i>O. oryzivora</i>

Abstract

Abstract Field sampling of grasses growing in and near rice fields at 12 sites in Nigeria during April/May 1994 recorded the presence of galls on Paspalum scrobiculatum at densities of up to 10.9 galls per m 2 . These galls were induced by Orseolia bonzii Harris, sp. n. , which is described. This species is morphologically close to, but distinct from, the African rice gall midge, Orseolia oryzivora Harris &amp; Gagné, with which it has been confused in earlier studies of that pest species. In host-transfer experiments O. bonzii did not transfer to rice, Oryza sativa . Six hymenopterous parasitoids were reared from galls of O. bonzii and the most abundant of these were Platygaster diplosisae Risbec, Aprostocetus nr. procerae (Risbec) and Neanastatus nr. cinctiventris Girault. Host-transfer experiments with the Platygaster and Aprostocetus species from O. bonzii on Paspalum indicated that the Platygaster may not transfer onto O. oryzivora on rice whereas the Aprostocetus does. The overlap between the parasitoid faunas of the two species of Orseolia is potentially useful as it may be possible to enhance the natural biological control of O. oryzivora by manipulating parasitoid populations on Paspalum .