The sexual dimorphic behaviour of adult Drosophila suzukii: elevated female locomotor activity and loss of siesta is a post-mating response

Abstract

The polyphagous Drosophila suzukii is a highly invasive species that causes extensive damage to a wide range of berry and stone fruit crops. A better understanding of its biology and especially its behaviour will aid the development of new control strategies. We investigated the locomotor behaviour of D. suzukii in a semi-natural environment resembling a typical summer in northern England and show that adult female D. suzukii are at least 4-fold more active during daylight hours than adult males. This result was reproduced in several laboratory environments and was shown to be a robust feature of mated, but not virgin, female flies. Both males and virgin females kept on a 12 h light:12 h dark (12LD) cycle and constant temperature displayed night-time inactivity (sleep) followed by weak activity in the morning, an afternoon period of quiescence (siesta) and then a prominent evening peak of activity. Both the siesta and the sharp evening peak at lights off were severely reduced in females after mating. Flies of either sex entrained in 12LD displayed a circadian pattern of activity in constant darkness confirming the importance of an endogenous clock in regulating adult activity. This response of females to mating is similar to that elicited in female Drosophila melanogaster by the male sex peptide (SP). We used mass spectrometry to identify a molecular ion (m/z, 5145) corresponding to the poly-hydroxylated SP of D. suzukii and to show that this molecule is transferred to the female reproductive tract during copulation. We propose that the siesta experienced by male and virgin female D. suzukii is an adaptation to avoid unnecessary exposure to the afternoon sun, but that mated females faced with the challenge of obtaining resources for egg production and finding oviposition sites take greater risks, and we suggest that the change in female behaviour is induced by the male SP.

Conservation of social effects (Ψ) between two species of Drosophila despite reversal of sexual dimorphism

“…For example, in D. suzukii, females move 4× more than males, and in one species of lizard movement was not sexually dimorphic despite more active males having higher reproductive success (Ferguson et al, 2015;Peterson & Husak, 2006).…”

“…In general, this manifests as males that move faster, but there are exceptions to this that also demonstrate the evolutionary lability of locomotory behavior. For example, in D. suzukii, females move 4× more than males, and in one species of lizard movement was not sexually dimorphic despite more active males having higher reproductive success (Ferguson et al., ; Peterson & Husak, ).…”

“…While few studies have focused on locomotion, it has been found to be an important component of sexual selection and fitness (Ferguson, O'Neill, Audsley, & Isaac, ; Husak & Fox, ; Lailvaux, Alexander, & Whiting, ; Long & Rice, ; Perry, ; Peterson & Husak, ). In D. melanogaster , locomotion is sexually antagonistic and is thought to have a shared genetic basis in males and females (Long & Rice, ).…”

Diel rhythms and sex differences in the locomotor activity of hawkmoths

“…As the stationary calling behavior appears to influence periods of female flight activity, this suggests that mated and virgin females may exhibit different patterns of behavior. While this is not observed in M. sexta (Sasaki and Riddiford, 1984), possibly due to the restricted time window of an 8 h scotophase, post-mating shifts in behavior have been reported in Drosophila melanogaster as well as the invasive Drosophila suzukii (Isaac et al, 2010;Ferguson et al, 2015) and the noctuid moth S. littoralis (Saveer et al, 2012). In the case of H. lineata, oviposition by mated females occurs throughout the day (Fig.…”

Sleep Deprivation alters the influence of biological sex on active-phase sleep behavior

“…In contrast, men spend more time in lighter stages of sleep at the expense of deeper stages of sleep and have more daytime sleep than women [2]. These studies, among others, provide clear evidence of human gender differences in sleep; furthermore, daytime sleep (napping) in males is observed across the animal kingdom from fruit flies to rodents [7–9]. This conservation of sex differences across species make animal models a useful tool to study these sleep differences.…”