Use of juvenoid insect growth regulators for management of cotton aphid, Aphis gossypii Glover, and silverleaf whitefly, Bemisia sp., populations

Abstract

Studies were conducted on developmental, reproductive, population, and organophosphate insecticide susceptibility effects of juvenoid insect growth regulators OIGRS) on two homopteran pest insects of cotton: cotton aphid, Aphis gossypii Glover, and silverleaf whitefly, Bemisia sp. Three jIGRs were evaluated: kinoprene, fenoxycarb, and piperonyl butoxide. The goal of this research was to determine if these jIGRs could be used to manage populations of cotton aphid and silverleaf whitefly. In field experiments conducted at Vernon/Chillicothe, Texas all three jIGRs were able to suppress population development and alter the normal population structure of cotton aphid. Fenoxycarb was determined to have the greatest population effects. These experiments indicated that jIGRs cause population structure disturbances in cotton aphid by arresting growth midway through nymphal development and interfering with JHregulated reproductive functions. Cotton aphids were exposed from first instar onward to 100 ppm residues of each of the three jIGRs on cotton leaves maintained on polysaccharide gel media (PGM) plates in the laboratory. In this study, JIGRs were shown to cause an average developmental delay of four to five days from first instar to adult. Silverleaf whitefly were exposed to I oo ppm residues of each of the three jIGRs on cotton leaves maintained on PGM plates in the laboratory. In this study, jIGRs were shown to cause an average developmental delay of two to three days from first instar to adult. Glass vial bioassays with cotton aphids and silverleaf whitefly showed that pre exposure to each of the three jIGRs caused increased sensitivity to the organophosphate insecticide diazinon by an average of ten-fold. Similar effects were seen with greenbugs, Schizaphis graminwn (Rondani). The effects of kinoprene, fenoxycarb, and piperonyl butoxide on development, reproduction, diazinon susceptibility, and population structure of cotton aphid and silverlea7L whitefly indicate potential roles for these compounds in future integrated management strategies. The data suggest that these compounds may be highly compatible with an integrated pest management approach to control of cotton aphid and silverleaf whitefly populations.