Effect of neem seed kernel extracts on stem borer damage and yield of upland rice in southeastern Nigeria

摘要

Stem borers are considered important insect pests of rice in most parts of the world. They have been implicated as the major constraint to rice production in West Africa (Ukwungwu 1990). Reliable data on yield loss caused by stem borers are not available in southeastern Nigeria. However, a screenhouse experiment at Badeggi, in the middle belt of Nigeria, showed that yield loss caused by Diopsis thoracica (West) ranged from 5% to 19% (Akinsola 1980). Dakuo et al (1991) reported a yield loss of 33% inirrigated rice caused by lepidopterous stem borers (Chilo zacconius, C. diffusilineus, Maliarpha separatella, and Sesamia calamistis) in Burkina Faso.