Field crickets (Gryllus campestris). Credit wildcrickets.org

Older male crickets attract more females – but have less sex

Older male crickets are better at getting females to live with them – but they mate less than younger rivals once they find a partner.

Meanwhile younger males have a harder time enticing females back to their burrows – but more mating happens if they succeed.

University of Exeter scientists studied field crickets to see if a male’s age affected how attractive females found them.

“Females choose mates to get the best genes for their offspring,” said Dr Rolando Rodríguez-Muñoz of the Centre for Ecology and Conservation on the University of Exeter’s Penryn Campus in Cornwall.

“It’s possible that the oldest males have the best genes because they’ve shown they can live for a long time.­

“On the other hand, females might favour younger males whose sperm have not accumulated possibly harmful mutations that will be passed on to offspring.

“Our results show a mixed picture, with older males more successful at pairing up with females, but mating less frequently once paired.”

The study found both pairing and mating were linked to successful reproduction, and there was no relationship between a male’s age at the time of mating and how many offspring he had.

“It seems that the age of a male is a poor guide to his suitability as a mate,” said Professor Tom Tregenza.

“This was reflected in the opposing effects it had on their success in pairing up and mating with females.”

The adult life of field crickets last just a few weeks, but previous research showed males “get old” in the sense of declining as they age.

Choosing an older male might seem like a good strategy for finding a long-lived male, but the new study found this was only partially effective – as younger males may live to the same or even older ages than those that emerged earlier in the year than them.

The study used ten years of video monitoring of all the crickets in a Spanish meadow.

The Exeter researchers have just launched an online game, Cricket Tales. Players will help analyse over a million hours of videos of crickets to understand how insects may be affected by climate change.

The paper, published in the journal Animal Behaviour, is entitled: “Older males attract more females but get less matings in a wild field cricket.”

Date: 24 May 2019