Small mosquitoes: large implications-effects of larval crowding and starvation on locomotor activity, adult biting frequency, and insecticide resistance in two strains of Aedes aegypti.

BACKGROUND

Stress during the larval phase of their post-embryonic development can result in reduced-size imagoes in mosquitoes. Water temperature, salinity, food availability, crowding, and predation are factors that affect larval development timing and adult size. In an earlier study we compared the transcriptomes and metabolomes of adult mosquitoes that were raised under standard conditions (large) with mosquitoes raised under stress conditions (small) and found significant changes. Continuing this line of inquiry, we compared the general activity, biting frequency, and insecticide resistance in small and large Aedes aegypti.

METHODS

In the study, we generated different-sized mosquitoes using larval crowding and nutritional stress. To compare the size-based variation in activity, we used the Locomotor Flight Activity Monitor (LAM-25) and a feeding assay to record the biting behavior of female mosquitoes. We then used a modified bottle assay to assess the levels of insecticide resistance in small and large mosquitoes of different strains.

RESULTS

We found that small and large mosquitoes have different activity and biting patterns over a 2-week time course; however, the cumulative number of engorgements was not different. After pyrethroid exposure, knockdown curves of small and large mosquitoes were similar in the susceptible University of Georgia Laboratory (UGAL )strain but different in the insecticide-resistant Puerto Rico strain.

CONCLUSIONS

Our results highlight the large knowledge gaps regarding the effects of mosquito size on vectorial capacity.