Alteration in Bacillus thuringiensis toxicity by curing gut flora: novel approach for mosquito resistance management
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Mosquitoes are known for acquiring resistance against insecticides in many ways, namely target side mutation, enzyme modification, sequestration, quick elimination, etc. But, the role of microflora present in abundance in the larval midgut is less explored with respect to their role in insecticide resistance. During the course of their development, mosquitoes are continuously exposed to microbes and have naturally acquired midgut microbial flora. This midgut flora can modulate the mosquito's susceptibility to Bacillus thuringiensis (Bt) infection by degrading toxic Bt protein forms through an unknown mechanism. In this study, we show that microbe-free aseptic mosquito larvae displayed an increased susceptibility to Bt toxicity compared to larvae harboring natural microbial flora. Fourth instar larvae of Anopheles stephensi were treated separately with penicillin, streptomycin, erythromycin (100 μg/ml), and mixtures of all three antibiotics and then analyzed for Bt toxicity. We have also examined the influence of the mosquito's midgut microbial flora under microaerophilic condition on the Bt protein degradation through plate, broth, TLC, and UV–vis spectrophotometric assay. A better understanding of the roles of microbiota in preventing Bt toxicity to mosquitoes could potentially lead to the development of new sustainable mosquito control strategies.
KeywordsMosquito Larva Larvicidal Activity Anopheles Stephensi Microaerophilic Condition Mosquito Midgut
Chandrashekhar D. Patil is thankful to CSIR (09/728 (0028)/2012-EMR-I) for the award of senior research fellowship.
- Abbott WS (1925) A method of computing the effectiveness of an insecticide. J Eco Entomol 18:265–266Google Scholar
- Jariyapan N, Saeung A, Intakhan N, Chanmol W, Sor-suwan S, Phattanawiboon B, Taai K, Choochote W (2013) Peritrophic matrix formation and Brugia malayi microfilaria invasion of the midgut of a susceptible vector, Ochlerotatus togoi (Diptera: Culicidae). Parasitol res DOI. doi: 10.1007/s00436-013-3404-5 Google Scholar
- Patil CD, Patil SV, Salunke BK, Salunkhe RB (2012) Insecticidal potency of bacterial species Bacillus thuringiensis SV2 and Serratia nematodiphila SV6 against larvae of mosquito species Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus. Parasitol Res 110:1841–1847PubMedCrossRefGoogle Scholar
- Rani A, Sharma A, Rajagopal R, Adak T, Bhatnagar RK (2009) Bacterial diversity analysis of larvae and adult midgut microflora using culture dependent and culture-independent methods in lab-reared and field-collected Anopheles stephensi—an Asian malarial vector. BMC Microbiol 9:96PubMedCrossRefGoogle Scholar
- Wirth MC (2010) Mosquito resistance to bacterial larvicidal toxins. Open Toxicol J 3:126–140Google Scholar