Alternative phenotypes of male mating behaviour in the two-spotted spider mite

Abstract

Severe intraspecific competition for mates selects for aggressive individuals but may also lead to the evolution of alternative phenotypes that do not act aggressively, yet manage to acquire matings. The two-spotted spider mite, Tetranychus urticae, shows male mate-guarding behaviour and male–male combat for available females. This may provide opportunity for weaker males to avoid fighting by adopting alternative mating behaviour such as sneaker or satellite tactics as observed in other animals. We investigated male precopulatory behaviour in the two-spotted spider mite by means of video-techniques and found three types of male mating behaviour: territorial, sneaker and opportunistic. Territorial and sneaker males associate with female teleiochrysales and spend much time guarding them. Territorial males are easily disturbed by rival males and engage themselves in fights with them. However, sneaker males are not at all disturbed by rival males, never engage in fights and, strikingly, never face attack by territorial males. Opportunistic males wander around in search of females that are in the teleiochrysalis stage but very close to or at emergence. To quickly classify any given mate-guarding male as territorial or sneaker we developed a method based on the instantaneous response of males to disturbance by a live male mounted on top of a brush. We tested this method against the response of the same males to natural disturbance by two or three other males. Because this method proved to be successful, we used it to collect territorial and sneaker males, and subjected them to morphological analysis to assess whether the various behavioural phenotypes are associated with different morphological characters. However, we found no statistical differences between territorial and sneaker males, concerning the length of the first legs, the stylets, the pedipalps or the body.Electronic supplementary materialThe online version of this article (doi:10.1007/s10493-013-9673-y) contains supplementary material, which is available to authorized users.

Population consequences of individual heterogeneity in life histories: overcompensation in response to harvesting of alternative reproductive tactics

“…Such a lack of sneaker (scrambler) discrimination has been observed in the spider mite Tetranychus urticae . In this species, males plastically adopt one of three ARTs to be the first to mate with a virgin female (the first mating ensures the paternity of most offspring, Helle ): opportunistic males continuously search for virgin females; fighter males guard female final instars and aggressively chase away rival males; or sneaker males guard (mount) female final instars but do not chase away rivals, and, crucially, neither are they chased away by other males (Sato et al ). Male spider mites can respond to sex pheromones released by females via olfactory cues (Margolies and Collins ), which led Sato et al () to hypothesise that sneaker males might mimic the odour of a female (e.g.…”

Fatal attraction: Male spider mites prefer females killed by the mite-pathogenic fungus Neozygites floridana

“…the non-sporulating cadavers, may favour the weakest male combatants (usually the smaller males, Potter et al, 1976;Oku, 2014) by rendering them less likely to guard dead and subsequently lethal females. Such a reversed fitness pattern may help to maintain the diversity in male mating strategies observed in T. urticae (Sato et al, 2013).…”

Parental effects of male alternative reproductive tactics (ARTs) on ARTs of haploid sons

“…Only the first copulation is effective, unless the female re‐mates shortly after the first insemination (Helle, ; Potter & Wrensch, ). ART expression by males is conditionally dichotomous and reversible, with fighting and sneaking phenotypes, and evident in male–male combat and pre‐copulatory guarding behaviour (Sato, Sabelis, Egas, & Faraji, ). Fighters and sneakers differ in behaviour but not in body size and morphology (Sato, Rühr, Schmitz, Egas, & Blanke, ; Sato et al, ).…”

“…ART expression by males is conditionally dichotomous and reversible, with fighting and sneaking phenotypes, and evident in male–male combat and pre‐copulatory guarding behaviour (Sato, Sabelis, Egas, & Faraji, ). Fighters and sneakers differ in behaviour but not in body size and morphology (Sato, Rühr, Schmitz, Egas, & Blanke, ; Sato et al, ). Mate finding occurs by males actively searching for females.…”

“…Fighters fight with other males, using their stylets and spinning behaviour, to gain access to T‐females and, during guarding, when challenged by other fighter males. Sneakers do not fight with other males to gain access to T‐females, do not challenge guarding males and are not challenged by other males during guarding (Sato et al, ). Sneakers may also secure the guarding position when competing males engage in fights.…”