ASPECTS OF THE BIOLOGY, ECOLOGY AND NATURAL BIOLOGICAL-CONTROL OF THEAFRICAN RICE GALL MIDGE, ORSEOLIA-ORYZIVORA HARRIS AND GAGNE (DIPT, CECIDOMYIIDAE) IN SOUTH EAST NIGERIA

Aspects of biology, ecology and parasitization of the African rice gal l midge (ARGM), Orseolia oryzivora Harris and Gagne, were studied in t he greenhouse and in the field in 1991 growing season in south east Ni geria. ARGM eggs hatched in 3 days and development (egg-adult) was com pleted in 26 days. About 1/3 of the eggs laid by mated female's failed to hatch. On average, 408 eggs were laid by mated females in a mean l ife of 3 days. Unmated females lived for 1.3 days and laid 88 eggs. Li ght trap catches of ARGM showed a preponderance of males early and lat e in the season with a female:male ratio of 1:2 and 1:3, respectively. Female:male ratio observed in the middle of the season was 1:1. Natur al enemies found parasitising ARGM were Platygaster diplosisae Risbec and Aprostocetus (= Tetrastichus) pachydiplosisae Schulten and Feijen. Maximum parasitization recorded for P. diplosisae and A. pachydiplosi sae was 72 % and 42 %, respectively. In the late season, combined para sitization by these two parasitoids reached 98 %. Certain spiders were also found to prey on adult ARGM.