Biocontrol Science and Technology (2017) 27, 169-179

Xiaohua Hu, Yajie Guo, Songqing Wu, Zhaoxia Liu, Tao Fu, Ensi Shao, Carballar-Lejarazú Rebeca, Guohui Zhao, Zhipeng Huang, Ivan Gelbic, Xiong Guan, Shuangquan Zou, Lei Xu and Lingling Zhang (2017)
Effect of proteolytic and detoxification enzyme inhibitors on Bacillus thuringiensis var. israelensis tolerance in the mosquito Aedes aegypti
Biocontrol Science and Technology 27 (2), 169-179
Abstract: Bacillus thuringiensis var. israelensis (Bti) is highly pathogenic to mosquito larvae and is widely used for mosquito control. Its mosquitocidal activity however is relatively low compared to many chemical insecticides. The detoxification mechanisms in the mosquito, among other things, might neutralize the Bti activity, resulting in resistance or tolerance. We tested whether or not the detoxification mechanisms against chemical insecticides might also operate against Bti, rendering it less effective. We targeted four enzymes in Aedes aegypti larvae involved in detoxification with inhibitors that have been used in resistance studies in chemical insecticides and assayed their effects on Bti toxicity. Results revealed that phenylmethanesulphonyl fluoride (PMSF), diethyl maleate, phenobarbital (PB), and piperonyl butoxide (PBO) altered Bti toxicity to various degrees. PMSF is a serine protease inhibitor that prevents Bti digestion and improves Bti activity. PB that induces several detoxifying enzymes had two different effects depending on the method of treatment. Mortality was higher when treatment with PB was discontinuous (149%) whereas with continuous treatment it was lower (101%). PBO, a typical cytochrome P450 inhibitor, increased Bti effect (159%). The combination of discontinuous pretreatment of larvae with PB followed by PBO had a synergistic effect and showed increased activity (146%). It appears that the mechanism for Bti resistance in mosquitoes is similar to that of chemical insecticides. Our studies indicate that we may be able to increase Bti activity by inhibiting some of the detoxification systems as active as broad spectrum chemical insecticides.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Xiong Guan

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Aedes aegypti
Bacillus thuringiensis var. israelensis (entomopathogen)	Aedes aegypti