Management of african rice gall midge <i>Orseolia oryzivora</i> Harris and Gagn&#233 with reference to time planting and natural enemies in southeastern Nigeria

Abstract

Field experiments were conducted at Abakaliki to evaluate the effect of time of planting (July 31, August 14 and August 28) and natural enemies in the control of African rice gall midge during the 2002 and 2003 cropping seasons. The experiment was laid out in randomized complete block design with three replications. The incidences of African rice gall midge were highest on rice planted on July 31 for both seasons and declined with the subsequent time of planting. The level of infestation by African rice gall midge was observed to depend on prevailing climatic factors. On the other hand, natural enemy found parasitizing African rice gall midge was Platygaster diplosisae Risbec. Parasitism by Platygaster diplosisae as a control measure of African rice gall midge was more severe as time of planting were delayed with 66.98 and 59.47% parasitism recorded on rice planted on August 28 for both years. This relationship was the significant negative correlation (r = -82 and -72 for 2002 and 2003 respectively) established between damage incidence and parasitism. Grain yield was least on rice planted on July 31 in all the experimental years. The highest grain yields were recorded on rice planted on August 14 for the two seasons. br>
Journal of Agriculture, Forestry and the Social Sciences Vol. 3 (2) 2005: pp.106-112