Bioefficacy of Formulated Insecticide Products against Adult German Cockroach, Blattella germanica

Abstract

The purpose of this study was to analyze bioefficacy test data of various insecticide active ingredi-ents and formulations provided to the Chemical Section, National Institute of Health (NIH) of Thailand from 2010-2014. The several different insecticide formulations were received from insecticide manufac-turers to obtain efficacy test reports for product registration with the Food and Drug Administration (FDA) of Thailand. The bioefficacy tests on treated surfaces were carried out according to standard methodologies of the NIH. The tests were evaluated against a laboratory strain of insecticide-susceptible adult female German cockroaches, Blattella germanica. The majority of sampled active ingredients were pyrethroids commonly used in public health such as cypermethrin (84 samples), deltamethrin (36), and bifenthrin (16). Additionally, other insecticide classes such as the neonicotinoid compound, imidacloprid (22) and chlorpyrifos (15), an organophosphate, were represented. The data revealed that almost all pyrethroid products produced 100.0% mortality in cockroaches at 72 hours after exposure. The time to knockdown 95% of the test population (KT₉₅ ) ranged from 6 to 28 minutes except for bifenthrin that required a longer time to obtain KT₉₅ (19-59 min). Chlorpyrifos displayed 100.0% mortality with KT₉₅ of 34-60 min. Only 36.4% of products containing imidacloprid demonstrated >95.0% mortality in cockroaches, a mini-mum acceptability classification with KT₉₅ between 16 and 60 min.