Females’ sequential mating decisions depend on both the quality of the courting male and the quality of the potential mates in a blood-sucking bug

Aversive sexual learning in the kissing bug Rhodnius prolixus: Modulation of different sexual responses in males and females

Although sexual learning can be a key process in the reproductive success of animals, research focused on the experience-dependent modulation of courtship in insects is scarce. In kissing bugs, the behavioural steps implicated in mating have been exhaustively studied, but not the involvement of learning in them. Our objective was to determine whether the sexual behaviour of Rhodnius prolixus could be modulated by experience. During training, couples were submitted to eight assays, in which they received a vibration (negative reinforcement) when the male attempted to copulate the female. Immediately after, they were separated, not allowing the occurrence of copulation. We found that along training, males' latency to perform a copulatory attempt increased, male's copulatory attempts were less frequent, and females' locomotor activity did not change. These results suggest that males, and not females, learned to avoid the vibration by reducing their intention to copulate. In post-training tests, conditioned males presented with new naïve females reverted to low copulatory attempt latencies, suggesting that the modulation was partner-specific. Besides, conditioned females increased their rejection frequencies to males' copulatory attempts, suggesting that a second type of learning occurred in females. These results constitute the first evidence of sexual learning in hematophagous insects. Males and females seem to change their selectivity according to their previous sexual experience. We discuss the relevance that this plasticity might have in the fitness of this epidemiologically relevant insect.

The role of male quality in sequential mate choice: pregnancy replacement in small mammals?

Females mainly increase their reproductive success by improving the quality of their mates and need to be discriminative in their mate choices. Here, we investigate whether female mammals can trade up sire quality in sequential mate choice during already progressed pregnancies. A male-induced pregnancy termination (functional 'Bruce effect') could thus have an adaptive function in mate choice as a functional part of a pregnancy replacement. We used bank voles (Myodes glareolus) as a model system and exchanged the breeding male in the early second trimester of a potential pregnancy. Male quality was determined using urine marking values. Females were offered a sequence of either high- then low-quality male (HL) or a low- then high-quality male (LH). The majority of females bred with high-quality males independent of their position in the sequence, which may indicate a pregnancy replacement in LH but not in HL. The body size of the second male, which could have been related to the coercion of females by males into remating, did not explain late pregnancies. Thus, pregnancy replacement, often discussed as a counterstrategy to infanticide, may constitute adaptive mate choice in female mammals, and female choice may induce pregnancy replacement in mammals.

The Effects of a Male Audience on Male and Female Mating Behaviour in the Blood-Sucking Bug Rhodnius prolixus

Social context is a key factor affecting sexual behaviour and cannot be neglected in gregarious species, such as triatomine blood-sucking bugs. Here we study the influence of the social context on the sexual reproductive behaviour of males and females of Rhodnius prolixus Stål. Specifically, we identify and compare the frequencies and sequence of sexual behaviours exhibited by a focal pair in presence or absence of a male audience. We expect that in presence of a male audience females increase their selectiveness level since the risk of losing infertile eggs decreases in presence of more candidates and females can benefit from copulating with a better quality male. Besides, in presence of potential rivals, we expect changes in the sexual behaviour of focal males, associated to a reduction in the risk of sperm competition. As expected, in presence of a male audience, females significantly increased the exhibition of rejection behaviour. Moreover, focal males exhibited shorter latencies to mount the female, longer duration of copula, and differences in their stereotyped behaviour exhibited during copula. We discuss the influence of the social context on the reproductive behaviour of females and males of R. prolixus.