The role of midgut symbiotic bacteria in resistance of Anopheles stephensi (Diptera: Culicidae) to organophosphate insecticides

Abstract

In the current study, the effects of the presence of symbiotic bacteria on the activity of the enzymes involved in An. stephensi resistance to temephos are evaluated for the first time. Four different strains (I. susceptible strain, II. resistant strain, III. resistant strain + antibiotic, and IV. resistant strain + bacteria) were considered in order to determine the possible effects of the symbiotic bacteria on their hosts’ resistance to temephos. The median values of all enzymes of susceptible strain were compared with those of other resistant strains. The results of this study indicated a direct relationship between the presence of bacteria in the symbiotic organs of An. stephensi and resistance to temephos. The profile of enzymatic activities in the resistant strain changed to a susceptible status after adding antibiotic. The resistance of An. stephensi to temephos could be completely broken artificially by removing their bacterial symbionts in a resistant population.

Keywords:

• Symbiotic bacteria
• Anopheles stephensi
• Insecticide resistance
• Temephos

Acknowledgements

Authors are thankful to the assistance of vice-chancellorship for research and technology at Tehran University of Medical Sciences (The code number of project: 90-02-27-14091).

Additional information

Funding

This work was supported by the Tehran University of Medical Sciences (IR) [grant number 90-02-27-14091].