Effects of certain insecticides on the predator Orius insidiosus and its prey Thrips palmi Paul Kennedy, Khan Ayub* Department of Life Sciences, University of the West Indies, St. Augustine, Trinidad *Corresponding author Email: ayub.khan@sta.uwi.edu
Online published on 30 April, 2019. Abstract Thrips palmi is a major pest of several economically important food crops. The mirid Orius insidiosus is an important predator of T. palmi in Trinidad and several other Caribbean islands. Its biocontrol effectiveness is hampered by frequent insecticide applications. Contact and leaf residual bioassays were conducted on both T. palmi and O. insidiosus with eleven commonly applied insecticides to determine the least and most toxic insecticide(s) to O. insidiosus and T. palmi, respectively. This information forms part of an Integrated Pest Management programme for T. palmi. Cypermethrin+ profenaphos and chlorfenapyr were observed to be the most toxic while imidacloprid was the least toxic to O. insidiosus adults. Fipronil, diafenthiuron and λ-cyhalothrin were the most toxic to T. palmi. Orius insidiosus survived for the longest period when exposed to chlorfenapyr but not significantly longer when exposed to acetamiprid, α-cypermethrin, or dimethoate. Alpha (α)-cypermethrin caused the fastest mortality in T. palmi while diafenthiuron took significantly longer to cause 50% mortality compared to α-cypermethrin and abamectin. The calculated Selectivity Ratios indicated that only fipronil, λ-cyhalothrin, acetamiprid, diafenthurion and imidacloprid favoured the predator. Leaf residue bioassays indicated that abamectin had the lowest LT50 for both O. insidiosus and T. palmi emphasizing the fact that abamectin degraded fastest and the residues left after application had the least effect on the predator/prey. Fipronil, λ-cyhalothrin, acetamiprid, diafenthurion, imidacloprid and abamectin might be incorporated into an IPM programme using O. insidiosus as a predator of T. palmi Top Keywords Thrips palmi, Orius insidiosus, Selectivity Ratio, leaf residual bioassays, IPM, cypermethrin, profenaphos, chlorfenapyr. Top |