Field performance of entomopathogenic nematodes and an egg parasitoid for suppression of corn borers in Egypt

Abstract

Two entomopathogenic nematodes (EPNs) and an egg parasitoid for controlling three corn borers (Sesamia cretica, Chilo agamemnon and Ostrinia nubilalis) in corn fields. EPNs, Heterorhabditis bacteriophora (BA1) and Steinernema carpocapsae (BA2) were applied to the control S. cretica (after 40 d post planting) on different planting dates. Three releases of Trichogramma evanescens were also conducted at two-week intervals to control C. agamemnon and O. nubilalis starting at tasseling time for the three planting dates; two release levels were used [20 & 30 cards (1000 parasitized eggs/ card)/acre]. During the first planting period, the spraying of EPN resulted in a 97% and 100% mortality of S. cretica larvae with H. bacteriophora (BA1) and S. carpocapsae (BA2) respectively, one week post spraying. After two weeks there was a 100% mortality of S. cretica on both EPN species. During the second planting period, the infestation by S. cretica was low, suggesting that this might be a suitable time for planting corn. There were a relatively high number of C. agamemnon and O. nubilalis eggs laid during the third planting period compared to first and second. The parasitism percentages by Trichogramma were high on all planting dates using the 30 cards/acre level compared to the second 20 cards/acre level. At season's end, the numbers of C. agamemnon and O. nubilalis larvae were significantly reduced on the Trichogramma release plots compared to on the control plots. The overall reduction in corn borer larvae on the treated plots using EPNs and later Trichogramma resulted in an increased yield compared to on the control plots. The results suggest that EPN and Trichogramma together can play a crucial role to control the three corn borers.