Canadian Forest Service Publications
Ecology of female mating failure / lifelong virginity: a review of causal mechanisms in insects and arachnids. 2019. Rhainds, M. Entomologia Experimentalis et Applicata: online early.
Issued by: Atlantic Forestry Centre
Catalog ID: 39615
CFS Availability: PDF (download)
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Sexual reproduction implies binary outcomes of competitive interactions for access to male gametes: lifelong virgin females with null fitness vs. mated females with variable (generally nonzero) fitness. Female mating failure has long remained a dormant concept in sexual selection theory in part because it is acutely maladaptive (lifelong virgins that do not reproduce are strongly selected against) and also due to widespread acceptance of the Bateman–Trivers paradigm (anisogamy and correlated sex roles). Based on recent scientific output on lifelong virginity acrossmultiple taxonomic groups in insects (Coleoptera, Diptera, Hemiptera, Lepidoptera, Odonata, Orthoptera, Strepsiptera), female mating failure has become a mainstay of sexual selection over the last decade. Lifelong virginity and senescence (death) are intertwined processes; old virgin females compensate for increased risk of lifelong virginity by becoming less choosy and increasing investment in mating-related activities. Low rates of female lifelong virginity (<5%) inmost natural populations of insects indicate that sex generally ‘works’ due to selective pressures acting on both males and females to enhance lifetime fitness. Mating failures are most common in insects with female flightlessness; these pressures may lead in evolutionary time to transitionary pathways from sexual reproduction to parthenogenesis. Female mating probability is affected by nonlinear density-dependent processes dependent upon the scale of observation (mate-encounter Allee effect at large spatial scales, mating interferences between females at small scales).Mate choice and sex role reversal (females being the active sexual partner) are ubiquitous in insects and arachnids with significant paternal investment, but consequences in terms of female lifelong virginity remain unknown. Logistically, conceptual development of female mating failure in insects is most limited by the lack of broadly applicable methods to assess rates of lifetime virginity among flighted females.
Plain Language Summary
In the ground-breaking monograph on spruce budworms (Morris 1963), David Greenbank introduced the concept of ‘female mating failure’ to designate female spruce budworms that emerge as functional adults but fail to mate during their lifetime and thus die as lifelong virgins (demographic consequence: reproductive loss due to null fecundity of virgins). Over the last decade, research on female mating failure has increased exponentially, as illustrated in this review article. Female mating failure is a neglected yet important component of population dynamics of many forest insects, including temporal shift from endemic to epidemic populations of gypsy moths or spruce budworms (mate-encounter Allee effect, or low mating probability in sparse populations), as well as the spread of invasive woodborers such as Tetropium fuscum.