Efficacy of Insect Growth Regulators against Red Tef Worm, Mentaxya ignicollis (Walker) (Lepdoptera: Noctuidae)

Abstract

Tef (Eragrostis tef (Zucc.), Trotter: Poaceae) is a staple food crop of Ethiopia where it is originated and diversified. Red tef worm (Mentaxya ignicollis) is a serious pest of tef grown on clay soils. Hence the present study emphasized on the evaluation of insect growth regulators to control Red Tef Worm. Laboratory study were carried out in completely randomized design with two insect growth regulators (lufenuron at doses 20, 40 and 60g a.i/ha and teflubenzuron at doses of 75, 112.5 and 150g a.i./ha) against 3rd instar larvae of RTW. The green house study was carried out in randomized complete block design with the two Chitin synthesize Inhibitors (CSIs) (lufenuron at dose of 40g a.i./ha and teflubenzuron at dose of 112.5g a.i./ha). Efficacy of CSIs in affecting the hatchablity of the eggs was also studied. From the laboratory and greenhouse experiments the IGRs, lufenuron and teflubenzuron, caused mortality after affecting the developmental stage of RTW larvae and also inhibited egg hatchability. In general, lefenuron (40g a.i./ha) was found to be effective and and showed high potency against 3rd instar larvae of RTW under laboratory and greenhouse conditions. Since the CSIs are safe to the environment and other beneficial organisms, it is recommended to be verified for usage under open and large field conditions for the control of RTW.