Abstracts (first author)


Why do spider mites re-mate?


Author(s): Rodrigues L, Clemente S, Carvalho J, Duarte F, Ponce R, Varela S, Olivieri I, Magalhães S


In Tetranychus urticae, only the first mating is effective, except if the interval between first and second copulations is shorter than 24 hours or if the first mating is interrupted. However, males often attempt to copulate with mated females. Here, we address this paradox. We first tested whether males prefer to mate with females that have mated within the preceding 24 hours or with those that have mated before that period. We found that males show no preference between these two types of females. Moreover, the time to mating was longer and the mating duration shorter when males mated with mated females, relative to virgins, irrespective of their timing of mating. This confirms a lack of distinction between different types of mated females and suggests that males are either less motivated to mate with mated females or that the second mating occurs for a different reason than siring offspring. Subsequently, we investigated the consequences of polyandry for the reproductive fitness of females, depending on the frequency and timing of the mating events. We predicted that if females benefit from polyandry, fecundity and survival of multiply mated females would be higher than those of once mated females. Indeed, multiply mated females have higher fecundity than once mated females, suggesting that females potentially benefit from mating multiply. No difference in survival and sex ratio was found between these females. Our data shows that females benefit from multiple matings, hence this behaviour is probably under female control. This result has implications for our understanding of mating behaviour in spider mites and other organisms.

Abstracts (coauthor)


Incomplete specific recognition can lead to the occurrence of reproductive interference (RI) - reproductive interactions between two species resulting in fitness loss for at least one of them. RI can play an important role in the coexistence of species, being especially important in the fate of introduced exotic species and in pest management.Tetranychus urticae and Tetranychus evansi are two closely related haplodiploid spider mite species that often coexist in solenaceous crops. Incomplete specific recognition occurs among these species: heterospecific matings were observed, although no hybrid progeny has been found. We tested two possible RI mechanisms: (1) the effect of mating with heterospecifics on virgin (haploid) offspring and (2), the consequences of heterospecific crosses for the offspring of females that have or will mate with conspecifics. Behavioural assays showed that (1) only T. urticae females and T. evansi males prefer to mate with conspecifics; (2) regarding latency to copulation individuals behave as virgins after mating heterospecifically, (3) T. urticae females copulate for a shorter period with heterospecifics than with conspecifcs. Results for fecundity and sex-ratio revealed that (1) for both species, fecundity of females mated with heterospecifics are similar to that of virgins - heterospecific crosses do not affect egg viability; (2) T. evansi females that mate with both conspecific and heterospecific males had higher fecundity than females that mated with a conspecific male only; this was not observed in T. urticae. (3) T. urticae females that mate with a heterospecific male after a conspecific mating had a lower percentage of female offspring. The results obtained point to the occurrence of asymmetric RI, in which T. evansi females benefits from mating with heterospecifics, whereas T. urticae pay a cost of such matings. These results may affect the coexistence of these species, a hypothesis requiring further testing.


Chairman: Octávio S. Paulo
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XIV Congress of the European Society for Evolutionary Biology

Organization Team
Department of Animal Biology (DBA)
Faculty of Sciences of the University of Lisbon
P-1749-016 Lisbon


Computational Biology & Population Genomics Group