Insecticide Resista Ce Profile, Synergism Studies And Bait Evaluatio Agai St Field-Collected Germa Cockroach, Blattella germanica (L.) (Blattodea: Blattellidae) From Singapore
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Date
2010-03
Authors
Chia, Ru Yuan
Journal Title
Journal ISSN
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Publisher
Universiti Sains Malaysia
Abstract
This research project focuses on the resistance profile, possible resistance mechanism
and bait evaluation of German cockroaches, Blattella germanica (Linnaeus) from Singapore.
Twenty-two strains of the German cockroach were collected from various localities in
Singapore and their resistance levels against various commercial insecticides were determined
using topical bioassay. Results revealed that insecticide resistance is prevalent in these German
cockroach populations. When compared against a laboratory susceptible strain, the levels of
resistance were low to very high for pyrethroid (deltamethrin and beta-cyfluthrin), low to high
for carbamate (propoxur) and organophosphate (chlorpyrifos), low to moderate for phenyl
pyrazole (fipronil), no or low for neonicotinoid (imidacloprid) and oxadiazine (indoxacarb).
One strain demonstrated broad spectrum resistance to most of the insecticides tested.
Pyrethroid resistance was reduced with the synergists, piperonyl butoxide (PBO) and
S,S,S-tributylphosphorotrithioate (DEF), implying monooxygenase- and esterase-based
metabolism in conferring resistance. Other additional mechanisms (e.g. kdr-type resistance)
may also be involved in some strains in which the resistance levels were not affected by the
synergists. Propoxur resistance was suppressed with PBO and DEF; coadministration of both
synergists resulted in complete negation of the resistance, indicating the involvement of both
monooxygenase and esterase. In six of the field strains, esterases could have played a major role
in chlorpyrifos resistance as greater synergism occurred with DEF than with PBO.
To assess the potential of using cockroach gel bait for control of these insecticideresistant
strains, the laboratory performance of four commercial gel baits formulated with
fipronil (Maxforce ® FC), hydramethylnon (Maxforce®), imidacloprid (Premise®) and
indoxacarb (Advion®) was evaluated. Continuous exposure tests were conducted for 14 days in
the presence of water, harbourage and alternative food for three life stages of the German
cockroach (male, female, mid-instars). With exception to the indoxacarb baits, all tested baits
exhibited variable effectiveness against the insecticide-resistant strains. The indoxacarb bait
showed excellent performance against all field strains with 100% mortality of all stages of test
insects within 9 days post-treatment. The efficacy of other baits against adult males was
encouraging (fipronil: 77.5 – 100%, hydramethylnon: 92.5 – 100%, imidacloprid: 82.5 – 100%).
When tested against the adult females and mid-instars of the field strains, fipronil caused 35.0–
95.0% and 18.8–93.8% mortality, respectively. The effectiveness of hydramethylnon bait was
moderate to high against adult females (42.5–100%) and mid-instars (40.0–97.5%), whereas the
imidacloprid bait showed poor to high performance against mid-instars (10.0–83.8%) and
moderate to high performance against adult females (52.5–100%). The likelihood of glucose or
bait aversion in these German cockroach populations cannot be ascertained at this stage.
Therefore, further investigations should be conducted.
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Keywords
The resistance profile, possible resistance mechanism , and bait evaluation of German cockroaches