A Novel Technique for Feeding and Confirming Uptake of Bacteria in Larvae of the Southern House Mosquito, Culex quinquefasciatus (Diptera: Culicidae)

Jonathan C. Geavgaard, Matthew W. Turnbull, Tamara L. McNealy

Abstract


Aquatic macroinvertebrates play important roles in freshwater ecosystems. The larvae of the vector mosquito Culex quinquefasciatus Say (Diptera: Culicidae) primarily reside in standing water rich in organic matter; these conditions are also suited for growth of microbial biofilms. As microbes serve as a food source for larvae, the study of interactions between microbial biofilms and C. quinquefasciatus can aid in understanding the routes by which aquatic larvae can acquire pathogens, and the role such larvae may play in environmental persistence of microorganisms. Studies in butterflies, nematodes, and ticks have described interactions with bacteria acquired by the oral route, including arthropods that play a role in dissemination of bacteria on beet plants. In pursuit of these goals, this manuscript describes a new protocol for investigating larval mosquito feeding on microbial biofilms. Fluorescent microscopy and GFP expressing bacterial strains were used to show larval acquisition and midgut localization of bacteria from both planktonic and biofilm sources. PCR testing for the GFP plasmid confirmed presence of the test strain in fed larvae. The results of microscopy and PCR assays demonstrate that Culex quinquefasciatus larvae will feed on microbial biofilms in a laboratory environment. The efficiency of studying microbial fate through common microscopic and molecular techniques, in combination with an easily maintained vector insect colony, means this approach can be used to investigate a multitude of research questions relating to microbial effects on larval physiology, fitness, and conditioning.

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