Abstract
Simple SummaryFluorescent powders are one of the most used materials for externally marking mosquitoes, such as Aedes aegypti, a vector of numerous human pathogens. They can be used to explore multiple biological questions related to population size, dispersal, and other interactions related to the spread of mosquito-borne diseases. To ensure marking practical aspects and that these powders do not interfere with mosquito natural behaviors, differentiation of multiple colors applied externally in the same mosquito, their impact on mating, and their transference between individuals after copulation and same-sex interactions were studied. Multiple color differentiation was possible, except for green–yellow combination. No important effect of powder marking was found on any of the mosquito mating phases: coupling (recognition and genital contact), copulation (genitalia engagement and semen transfer), and insemination (deposition of the sperm in the female reservoirs). After copulation with a powder-treated mate, >80% of females and all males had powder in genitalia, legs, and wingtips. The transfer of powder, between same-sex individuals, occurred only in males. In general, fluorescent powders had a little observable effect on Ae. aegypti mating, suggesting that these markers do not alter this important vector life-history trait and are a useful and viable tool for mosquito studies.Five different fluorescent powders (orange, yellow, green, blue, and violet) were tested on Aedes aegypti adults to evaluate the differentiation of multiple fluorescent powder colors applied externally in the same female mosquito, their effect on coupling time, copulation time, insemination success, mate choice, and the extent of transference of powders between marked and unmarked individuals, either during copulation or same-sex interactions. Marking with multiple powders was evaluated after applying different powders in the same female at different times and combinations. The comparative effect of powders on mating was explored using different cross-combinations of marked/unmarked couples. Transference of powders between marked/unmarked individuals after copulation was checked in mated individuals, and between same-sex interactions by allowing them to interact under crowded and uncrowded conditions. Identification of the colors included in multiple markings in the same individual was possible when exploring almost all combinations (exception: green–yellow). No important effect of powder marking between cross-combinations was found on coupling time (overall 95% CI (Confidence Interval) 37.6–49.6 min), copulation time (overall 95% CI 17–20 s), insemination success, nor their mate choice. Transferred powder after copulation activity, concentrated in genitalia, legs, and the tip of wings, occurred in >80% of females and 100% of males. Powder transference in legs and genitalia, between same-sex individuals, occurred only in males (ranged between 23–35%) under both density conditions. The lack of important effects of these powders on the studied aspects of Ae. aegypti provides information about their usefulness and limitations, which should be recognized for future applications and to avoid bias.
Highlights
A wide variety of methods and techniques for marking mosquitoes have been developed, many of which have been used to explore multiple biological questions related to population size and dynamics, dispersal, feeding behavior, trophic-level interactions, and other ecological interactions [1,2]
Five different water-insoluble fluorescent powders, with a specific gravity of 1.2 and a mean particle size of 4.5 μm, of the brand Day-Glo® ECO Series [3] were tested on Ae. aegypti adults to evaluate their differentiation in the same individual after being marked with more than one powder, their effect on the mosquito mating process and mate choice, and their transference between marked and unmarked individuals
In contrast to observations made in Drosophila adults, we found that the order of application had an effect in determining which powder was most detected, but not defining whether the two-powder combination was distinguishable from either powder alone [7]
Summary
A wide variety of methods and techniques for marking mosquitoes have been developed, many of which have been used to explore multiple biological questions related to population size and dynamics, dispersal, feeding behavior, trophic-level interactions, and other ecological interactions [1,2]. Other applied questions remain unanswered, like potential difficulty in distinguishing individual markers when used in a multiple marker approach in which individuals are marked with more than one fluorescent powder at different times and combinations, their impact on mosquito mating, and their transference during copulation or same-sex interactions. Addressing these questions will improve our ability to reliably use fluorescent powder marking of individuals to further elucidate mosquito biology, especially in field settings, and develop novel control strategies that exploit mosquito biology
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