Video Recording Can Conveniently Assay Mosquito Locomotor Activity

Abstract

Anopheles gambiae and Aedes aegypti are perhaps the best studied mosquito species and important carriers of human malaria and arbovirus, respectively. Mosquitoes have daily rhythms in behaviors and show a wide range of activity patterns. Although Anopheles is known to be principally nocturnal and Aedes principally diurnal, details of mosquito activity are not easily assayed in the laboratory. We recently described FlyBox, a simple tracking system for assaying Drosophila locomotor activity rhythms and thought that it might also be applicable to monitoring mosquito activity. Indeed, we show here that FlyBox can easily, conveniently, affordably and accurately measure the activity of Anopheles as well as Aedes over several days. The resulting profiles under light-dark as well as constant darkness conditions are compatible with results in the literature, indicating that this or similar systems will be useful in the future for more detailed studies on a range of insect species and under more diverse laboratory conditions.

Figure 1

Schematic of FlyBox. Illustration of FlyBox schematic (upper panel) and the front view of FlyBox (lower left panel) were shown. The example of recording image used for mosquito behavior monitoring is provided in lower right panel.

Figure 2

(A) Locomotor activity of Anopheles gambiae and Aedes aegypti mosquitoes under LD conditions. Double-plotted actograms show the average locomotor activity of individually monitored males and females of both species under cycles of 12 h light and 12 h of dark (LD) over four days. ZT indicates zeitgeber time. Gray shading indicates darkness. (B) Locomotor activity of Anopheles gambiae and Aedes aegypti mosquitoes under DD conditions. Double-plotted actograms show the average locomotor activity of individually monitored males and females of both species under constant dark (DD) over four days. Light gray background represents “subjective day” and dark gray background “subjective night”. n = 11–12.

Figure 3

Comparisons of daytime and nighttime mean activity of Anopheles gambiae and Aedes aegypti mosquitoes under LD conditions. Light gray bars represent “day” and dark gray bars represent “night”. n = 10–12. *p < 0.05 and **p < 0.01 by student’s T-test.

Figure 4

Analysis of circadian period and quantification of rhythmic and arrhythmic male and female Anopheles gambiae and Aedes aegypti. There are no apparent sex differences, and LD periods are clamped at 24 hr as expected. (A) Mean ± SEM of Anopheles gambiae and (B) Aedes aegypti period in hours. ***p < 0.001, Ordinary one-way ANOVA. n = 18–23. Anopheles gambiae (C) and Aedes aegypti (D) mosquitoes under LD and DD conditions. % R (blue) represents the percentage of rhythmic flies. % AR (pink) represents the percentage of arrhythmic mosquitoes. n = 23–24.

Figure 5

Mean locomotor activity profiles. (A) Profiles of females, Anopheles gambiae vs. Aedes aegypti; (B) Profiles of males, Anopheles gambiae vs Aedes aegypti; (C) Profiles of Aedes aegypti, males vs females; (D) Profiles of Anopheles gambiae, males vs females. The graphs show the mean activity of 23–24 mosquitoes during each ZT hour over 4 days in LD12:12.

Figure 6

Mean locomotor activity profiles of virgin Anopheles, males vs females. The graphs show the mean activity of 23–24 mosquitoes during each ZT hour over 4 days in LD12:12.