Effectiveness of some local and commercial isolates of entomopathogenic nematodes in controlling Tuta absoluta larvae and comparing them with the pesticide Oxymatrine in the laboratory

Abstract

A laboratory study was conducted to evaluate the effectiveness of local isolates Oscheius onirici, Oscheius myriophilus, commercial isolates Heterorhabditis bacteriophora and Steinernema carpocapsae of entomopathogenic nematodes (EPNs) to compare them with the plant pesticide Oxymatrine in controlling the tomato leaf miner Tuta absoluta on the tomato cultivar Ala in the laboratory. The results showed that the local biological treatment Oscheius spp gave the highest mortality rate for the third-stage larvae at concentrations of 100, 300, and 500 Ijs/ml and a cumulative killing rate of 100% during 5 days, respectively, followed by the commercial isolate H. bacteriophora, which had a mortality rate of 100%. There were no significant differences between the three isolates; the concentration of 500 Ijs was the highest cumulative killing rate for the biological treatments. At the same time, there was a significant difference between the commercial isolate S. carpocapsae and the other isolates, as the larval mortality rate reached 40% compared to the chemical pesticide.The mortality rate of the third-stage larvae T. absoluta at concentrations of 1.8, 1.5, and 1 ml during 5 days reached 40%, 36%, and 30%, respectively, as the recommended concentration of 1.8 gave the highest cumulative killing rate of 40% and with a highly significant difference between the three isolates. Still, there was no significant difference between the commercial isolates. The chemical pesticide S. carpocapsae reached a 40% mortality rate over 5 consecutive days.