Abstract

BackgroundThe study of physiological and behavioral traits of mosquito vectors has been of growing relevance for the proposition of alternative methods for controlling vector-borne diseases. Despite this, most studies focus on the female’s traits, including the behavior of host seeking, the physiology of disease transmission and the site-choice for oviposition. However, understanding the factors that lead to males’ reproductive success is of utmost importance, since it can help building new strategies for constraining population growth. Male behavior towards mating varies widely among species and the communication between males and females is the first aspect securing a successful encounter. Here we used an automated monitoring system to study the profile of locomotor activity of Aedes aegypti males in response to female’s presence in an adapted confinement tube. We propose a new method to quantify male response to the presence of females, which can be potentially tested as an indicator of the success of one male in recognizing a female for mating.ResultsLocomotor activity varies in daily cycles regulated by an endogenous clock and synchronized by external factors, such as light and temperature. Our results show the previously described startle response to light, which is displayed as a steep morning activity peak immediately when lights are on. Activity drops during the day and begins to rise again right before evening, happening about 1.5 h earlier in males than in females. Most interestingly, males’ activity shows a double peak, and the second peak is very subtle when males are alone and relatively more pronounced when females are present in the confinement tubes. The switch in the peak of activity, measured by the herein suggested Peak Matching Index (PMI), was significantly different between males with and without females.ConclusionsThe adapted monitoring system used here allowed us to quantify the response of individual males to nearby females in terms of the extent of the activity peak displacement. In this direction, we created the peak matching index (PMI), a new parameter that we anticipate could be interpreted as the inclination of males to respond to females’ presence, and further tested as an indicator of the potential for finding females for mating.

Highlights

  • The study of physiological and behavioral traits of mosquito vectors has been of growing relevance for the proposition of alternative methods for controlling vector-borne diseases

  • Our results show that both males and females of Ae. aegypti mosquitoes have a startle response to light, producing a steep morning activity peak at ZT0 (Zeitgeber 0), immediately when lights are on

  • Locomotor activity shows a double peak in males and the second peak (E2) is very subtle when males are alone, and significantly more pronounced (39.5 ± 31) when virgin females are present in the confinement tubes (F (3, 331) = 13.68, P < 0.0001, Tukey’s test: P = 0.049) (Fig. 2, Table 1)

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Summary

Introduction

The study of physiological and behavioral traits of mosquito vectors has been of growing relevance for the proposition of alternative methods for controlling vector-borne diseases. The study of male behavioral and physiological traits has been historically neglected in species of blood-sucking mosquitoes. This is mostly because males do not bite and are not vectors of diseases themselves [1,2,3,4]. Due to the increase of insecticide resistance [12,13,14,15,16], the World Health Organization (WHO) encourages the application of methods that go beyond the use of insecticides and target the fertility of adults and the viability of eggs and larvae These methods benefit from the knowledge of the insect vector’s reproduction and embryology and must have the potential of reducing population growth. It is of great interest to study the factors that mediate the communication between males and females before the mating event, and knowledge is currently lacking for Ae. aegypti and other insect vectors [18]

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