Insecticide Resistance Studies on German Cockroach (Blattella Germanica) Strains to Malathion, Propoxur and Lambdacyhalothrin Publisher



Kakehkhani A¹ ; Nazari M¹ ; Nasirian H² Show Affiliations
Source: Chulalongkorn Medical Journal Published:2020

Abstract

Background: The German cockroach has been known as the most invading human dwelling cockroach species. For managing the insecticide resistance, it is periodically a substantial need to evaluate susceptibility level of the German cockroaches to consuming insecticides. Objective: To evaluate resistance of the German cockroaches to malathion, propoxur and lambdacyhalothrin. Methods: Three cockroach strains including susceptible reference, and two wild strains were provided, maintained and colonized. The wild strains were collected from two hospitals of Sanandaj in Iran. Surface contact method was used for bioassay using standard glass jar procedure. The adult male cockroaches were treated with 5-6 insecticide dose exposures at a 30-min period. The dose exposures of malathion were 6.25, 12.5, 25, 50 and 100, and 25, 50, 100, 200 and 400 mg/m2 for susceptible and wild cockroach strains, respectively. The dose exposures of propoxur were 5, 10, 20, 40 and 80, and 20, 40, 80, 160 and 320 mg/m2 for susceptible and wild cockroach strains, respectively. The dose exposures of lambdacyhalothrin were 0.075, 0.15, 0.3, 0.6 and 1.2, and 0.3, 0.6, 1.2, 2.4 and 4.8 mg/m2 for susceptible and wild cockroach strains, respectively. Each dose exposures were replicated 3 times (10 cockroaches for each replicate). Control groups received acetone alone. Results: The lethal doses50 (LDs50) of the susceptible strain were 30.01, 16.56 and 0.303 for malathion, propoxur and lambdacyhalothrin respectively. While the LDs50 of the wild cockroach strains were 157.45, 74.59 and 0.506 for malathion, propoxur and lambdacyhalothrin, respectively. Compared to the susceptible strain, the wild German cockroach strains were more tolerant to malathion and propoxur. Compared to the susceptible strain the wild German cockroach strains were more sensitive to lambdacyhalothrin, confirmed also by a significant difference (P = 0.033). The results of probit analysis and regression lines of treated insecticides indicate that the German cockroach was resistant to malathion and propoxur while susceptible to lambdacyhalothrin. The resistance ratio50 (RR50) of the malathion and propoxur insecticides were about 5.0 folds. Conclusion: The study supports that malathion and propoxur should not be used for control of the German cockroaches. An appropriate choice is to use lambdacyhalothrin due to negative cross-resistance effect which occurs here. The study also provides a baseline of resistance data towards a few insecticides in a few German cockroach populations in Iran. © 2020, Chulalongkorn University Printing House. All rights reserved.