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Immature mating as a novel tactic of an invasive widow spider

Project description

Why males prefer the ‘killer’ widow spiders

In the brown widow spider Latrodectus geometricus, males actively facilitate cannibalism through a specific copulatory posture. Being cannibalised brings them paternity benefits over their non-cannibalised competitors. Males can, however, also mate with immature females few days before their final moult. These immature matings result in successful offspring production, but never in cannibalism. Interestingly, when given a choice, males prefer mating with adult, cannibalistic females over the immature females. The EU-funded Widow Spider Mating project will test the hypothesis that immature mating is costly for the male, suggesting a trade-off between mating rate and reproductive assurance.


Female widow spiders are frequently cannibalistic, but males of the invasive brown widow spider Latrodectus geometricus can avoid being eaten by mating with immature females that never attack their mating partners. Although immature females are generally assumed unable to mate due to the lack of developed external genitalia, in this species they readily mate and produce offspring at maturity. Nevertheless, despite the benefits arising from immature mating, males consistently prefer to mate with adult, cannibalistic females. Sexual cannibalism is generally considered detrimental for the male, but in L. geometricus it represents a male adaptive strategy which brings advantages in terms of lower female propensity to re-mate. Therefore, its lack in immature mating may come at cost of paternity loss due to female re-mating. I suggests a trade-off between mating rate and reproductive assurance. In the proposed project, I will test the hypothesis that immature mating is costly for the male. I will investigate the mechanism of immature mating as well as ultimate fitness consequences for the male in terms of paternity. I will use a multidisciplinary approach, combining state-of-the-art behavioural, morphological and molecular methods. Utilizing the expertise and infrastructure in two excellent institutions: University of Greifswald and University of Toronto, I will enhance international collaboration and knowledge transfer among research teams. At the University of Greifswald, mating systems are studied by a combination of behavioural and morphological approaches. Using advanced tools to study and visualize internal structures crucial for understanding reproductive biology, I will characterize the morphological mechanisms and structures associated with immature mating. At the University of Toronto, I will use established husbandry infrastructure and molecular techniques to determine behavioural correlates of paternity, and links to female reproductive output.


Net EU contribution
€ 233 434,56
17489 Greifswald

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Mecklenburg-Vorpommern Mecklenburg-Vorpommern Vorpommern-Greifswald
Activity type
Higher or Secondary Education Establishments
Total cost
€ 233 434,56

Partners (1)