Skip to content

Research at St Andrews

Sex ratios, virginity and local resource enhancement in a quasisocial parasitoid

Research output: Contribution to journalSpecial issue


Open Access permissions



Apostolos Kapranas, Ian C.W. Hardy, Xiuyun Tang, Andy Gardner, Baoping Li

School/Research organisations


Sclerodermus harmandi is an economically beneficial species of parasitoid wasp that also has an unusual level of sociality: groups of female foundresses reproduce on a single host and exhibit cooperative post-ovipositional brood care. The beneficial effects females have on each other’s reproductive success provides, via the theory of local resource enhancement (LRE), an explanation for their female biased progeny sex ratios which is part of the same framework for understanding sex ratio evolution as the more often invoked theory of local mate competition (LMC). Here we show that S. harmandi sex ratios are over-dispersed, with high variance largely attributable to the common occurrence (60%) of developmental mortality. Developmental mortality is also positively associated with the proportion of broods which contain only females at emergence (virgin broods). Virginity is also more common when broods are produced by smaller numbers of foundresses. Virginity is expected to be disadvantageous under LRE, as it is under LMC, but theory for LRE is less extensively developed. We suggest approaches for the development of LRE theory, in particular using models of “population elasticity” in which the intensity of kin competition is reduced because extra resources are available to local populations that are more cooperative. For S. harmandi, such extra resources may include large hosts that can only be successfully utilized when multiple foundresses cooperate.



Original languageEnglish
Pages (from-to)243-251
JournalEntomologia Experimentalis et Applicata
Issue number2
Early online date28 Apr 2016
Publication statusPublished - May 2016

    Research areas

  • Sclerodermus harmandi, Bethylidae, LRE, LMC, Developmental mortality, All-female broods

Discover related content
Find related publications, people, projects and more using interactive charts.

View graph of relations

Related by author

  1. Resource heterogeneity and the evolution of public-goods cooperation

    Stilwell, P., O'Brien, S., Hesse, E., Lowe, C., Gardner, A. & Buckling, A., 13 Jan 2020, (Accepted/In press) In : Evolution Letters.

    Research output: Contribution to journalArticle

  2. The demography of human warfare can drive sex differences in altruism

    Micheletti, A. J. C., Ruxton, G. D. & Gardner, A., 11 Jan 2020, (Accepted/In press) In : Evolutionary Human Sciences.

    Research output: Contribution to journalArticle

  3. Price's equation made clear

    Gardner, A., 4 Jan 2020, (Accepted/In press) In : Philosophical Transactions of the Royal Society. B, Biological Sciences.

    Research output: Contribution to journalArticle

  4. Genomic imprinting as a window into human language evolution

    Hitchcock, T., Paracchini, S. & Gardner, A., Jun 2019, In : BioEssays. 41, 6, 11 p., 1800212.

    Research output: Contribution to journalArticle

Related by journal

  1. Sex allocation and the evolution of insemination capacity under local mate competition

    Martel, V., Shuker, D. M., Boulton, R. A., Damiens, D. & Boivin, G., May 2016, In : Entomologia Experimentalis et Applicata. 159, 2, p. 230-242 13 p.

    Research output: Contribution to journalArticle

  2. Nectar resource diversity organises flower-visitor community structure

    Potts, SG., Vulliamy, B., Roberts, S., O'Toole, C., Dafni, A., Ne'eman, G. & Willmer, P. G., Nov 2004, In : Entomologia Experimentalis et Applicata. 113, 2, p. 103-107 5 p.

    Research output: Contribution to journalArticle

ID: 214291183