Costs and benefits for water strider (Aquarius paludum) females of carrying guarding, reproductive males

Abstract

We describe the mating system of Aquarius paludum insularis based on field observations and test hypotheses about the effects of body size, hunger level and post‐copulatory guarding on reproductive performance. The mating sequence of this species was typical for temperate water striders, except that most oviposition was carried out by tandem pairs, most of which were submerged. Mate guarding continued until the end of oviposition, lasting up to 18.2 h, which was much longer than that recorded for other species of water striders. Pair partners changed after oviposition. Extended contact guarding reduced female mobility. In the case of females that carried long‐winged males, there was a significant reduction in speed and stride between tandem as opposed to single females. However, when short‐winged males were carried, there was not a significant difference. Short‐term foraging efficiency did not differ significantly between tandem and single females, and thus did not reflect the difference in mobility. Hunger level did not significantly affect female mating receptivity. Although the number of harassment bouts by unpaired males did not differ between single and tandem females, single females suffered significantly more harassment. Females were able to lay fertilized eggs for about 15 days after a single copulation, but they accepted long guarding and multiple mating during this period as well. The cost of resisting male mating attempts appears to be greater than the cost of carrying males.

The extraordinary mating system of Zeus bugs (Heteroptera:Veliidae:Phoreticovelia sp.)

“…Earlier studies report no assortative mating by wing morph in other semiaquatic insects (Fairbairn 1988;Arnqvist et al 1996;Amano and Hayashi 1998) and we are unaware of any previous example of such strong homogamy by wing morph in any insect. Our field data suggested that this is not a result of differences in habitat preference between morphs, as confirmed by the fact that assortative mating was also observed in the laboratory.…”

Influence of male density on guarding behaviour in the water strider Aquarius paludum (Heteroptera: Gerridae)

“…The termination of copulation was monitored by direct observation at intervals of approximately 15 min because it could not be clearly determined from video recordings. However, the copulation duration was not recorded because the mean duration of copulation for A. paludum was previously reported to be 7.8 min (Amano & Hayashi, 1998), meaning that our intervals of direct observation (15 min) were too long to detect any differences in copulation duration. Furthermore, continual observation throughout the experiment to record the exact duration of copulation may have disrupted the post-mating behaviour of the water striders.…”

“…Thus, male water striders that "guard" their mates by remaining mounted after copulation have an improved chance of retaining paternity (Rowe, 1992;Rowe et al, 1994;Amano & Hayashi, 1998). In addition, the mating behaviour of water striders is easy to observe because it follows a well established sequence, including the male mating attempt, pre-mating struggle, copulation, post-mating struggle and post-mating guarding behaviour (Amano & Hayashi, 1998).…”

“…In nature, the mean duration of guarding behaviour (i.e., time between copulation and oviposition) in A. paludum is 18.2 h (Amano & Hayashi, 1998). Therefore, when males do not encounter other males for more than 18.2 h, they may not exhibit guarding behaviour.…”

"Cryptic" direct benefits of mate choice: choosy females experience reduced predation risk while in precopula

“…Although guarding behavior is generally considered from the male's point-of-view, as a male time investment strategy, females may also benefit from the presence of a guarding male. Several studies have assessed how pairing, relative to being single, affects components of female fitness (e.g., Waage 1979;Tsubaki et al 1994;Ward 1986;Lovell-Mansbridge and Birkhead 1997;Amano and Hayashi 1998;Cothran 2004;Rodríguez-Muñoz et al 2011); however, few have considered how the phenotype of the female's mate mediates these effects.…”