Insecticide Resistance Profiles and Synergism in Field Populations of the German Cockroach (Dictyoptera: Blattellidae) From Singapore

Abstract

The resistance profiles of 22 field-collected populations of the German cockroach, Blattella germanica (L.) (Dictyoptera: Blattellidae), from various localities in Singapore were determined by topical bioassay against novel and conventional insecticides from six classes: (1) pyrethroid (beta-cyfluthrin, deltamethrin), (2) carbamate (propoxur), (3) organophosphate (chlorpyrifos), (4) phenyl pyrazole (fipronil), (5) neonicotinoid (imidacloprid), and (6) oxadiazine (indoxacarb). Compared with a laboratory susceptible strain, resistance levels ranged from 3.0 to 468.0x for the pyrethroids, from 3.9 to 21.5x for the carbamate, from 1.5 to 22.8X for the organophosphate, from 1.0 to 10.0X for phenyl pyrazole, and were absent or low for the neonicotinoid (0.8-3.8x) and the oxadiazine (1.4-5.3x). One strain demonstrated broad-spectrum resistance to most of the insecticides. Synergism studies using piperonyl butoxide (PBO) and S,S,S-tributylphosphorotrithioate (DEF) in combination with a discriminating dose (LD99) of selected insecticides were conducted to test for possible resistance mechanisms. Resistance to pyrethroid was reduced with PBO and DEF, suggesting the involvement of P450 monooxygenase and esterases in conferring resistance. Propoxur resistance also was suppressed with PBO and DEF, and coadministration of both synergists resulted in complete negation of the resistance, indicating the involvement of both P450 monooxygenase and esterase. In six B. germanica field strains evaluated, esterases were found to play a role in chlorpyrifos resistance, whereas the P450 monoxygenase involvement was registered in three strains. Additional resistance mechanisms such as kdr-type and Rdl mutation contributing toward pyrethroid and fipronil resistance, respectively, also may be involved in some strains in which the resistance levels were not affected by the synergists. We conclude that insecticide resistance is prevalent in field German cockroach populations in Singapore.

Development of Diagnostic Insecticide Concentrations and Assessment of Insecticide Susceptibility in German Cockroach (Dictyoptera: Blattellidae) Field Strains Collected From Public Housing

“…Our findings are consistent with other studies showing significant indoxacarb (Gondhalekar et al 2013, Ko et al 2016a) and fipronil (Holbrook et al 2003, Chai and Lee 2010, Gondhalekar et al 2011) resistance in German cockroaches. Resistance to indoxacarb and fipronil in the I-IN and D-IL strains are likely the result of prior selection pressure.…”

“…In the case of imidacloprid, similar results were obtained in vial and no-choice feeding bioassays with gel bait. For technical imidacloprid assays, mortality was not different between the lab and field strains, which is a similar result to that obtained previously (Chai and Lee 2010). However, with technical imidacloprid 100% mortality could not be achieved, suggesting the potential for reduced imidacloprid efficacy.…”

“…Reports of widespread pyrethroid resistance in German cockroaches and associated control failures are abundant (Valles and Yu 1996, Wei et al 2001, Limoee et al 2006, Chai and Lee 2010). Cochran previously showed pyrethroid-resistant German cockroaches could be selected within six generations by exposing a lab susceptible strain to permethrin or fenvalerate (Cochran 1987).…”

Variation in susceptibility of laboratory and field strains of three stored‐grain insect species to β‐cyfluthrin and chlorpyrifos‐methyl plus deltamethrin applied to concrete surfaces

“…In Australia, resistance to cyfluthrin has been reported in Oryzaephilus surinamensis and Tribolium castaneum using filter paper and grain assays. Resistance to cyfluthrin was also reported in other insect species such as the housefly, Musca domestica L.; German cockroach, Blattella germanica (L.); beet armyworm, Spodoptera exigua (Hübner), and lesser meal worm, Alphitobius diaperinus (Panzer) . In the present study, Rhyzopertha dominica showed reduced susceptibility to chlorpyrifos‐methyl plus deltamethrin.…”

Development of strategies for monitoring indoxacarb and gel bait susceptibility in the German cockroach (Blattodea: Blattellidae)

“…It is proposed that indoxacarb is effective in controlling insects that have developed resistance to carbamates, organophosphates and pyrethroids 26. A recent study by Chai and Lee27 showed that German cockroach field populations from Singapore that were resistant to organophosphates, carbamates, pyrethroids and fipronil were susceptible to indoxacarb. In another study, indoxacarb gel bait treatments were reported to be effective in eliminating German cockroach infestations in a residential area where sprays of pyrethroids, insect growth regulators and other bait formulations had proven unsuccessful 11.…”