A species of New Zealand stick insect that was thought to produce only females has hatched a rogue male in the UK countryside – and scientists say the rare event could mean the animal is ready to start having sex.
Scientists at Massey University in New Zealand said they were “disbelieving” when colleagues in the UK reported they had found a male of the Acanthoxyla inermis stick insect, as the species has only ever been known to produce females.
“All Acanthoxyla species use parthenogenetics to reproduce, which means that the females lay viable eggs without the need for fertilisation by a male,” said Professor Morgan-Richards of the School of Agriculture and Environment at Massey University
“No males of any Acanthoxyla species have ever been recorded, until now.”
The specimen was discovered by a UK insect enthusiast in the Cornwall countryside, who suspected its odd appearance hinted at something unusual. DNA sequencing confirmed the specimen was a “mutant” male.
Professor Steve Trewick of Massey University said they had studied other species of New Zealand stick insects in captivity, which showed some inclination towards producing males.
“Like everything else in evolution this male is the product of a chance event and the important thing is, is that chance event going to be picked up and contribute to future generations? These rare events are the ones that become highly significant if natural selection picks up on them.”
The million-dollar question, said Trewick, was whether the male Acanthoxyla inermis had the ability to produce sperm and inseminate females.
But this was now impossible to know, as the creature, which is smaller and slighter than the female, was now housed in the national collection at the Natural History Museum in London; dead, dried and 18,000km away from New Zealand.
“It is a difficult road to get back into sexuality, but the fact it is almost universal shows that there must be an evolutionary advantage to it long term, to having males and females together produce offspring,” said Trewick, who was appealing to insect enthusiasts in the UK to keep their eyes peeled for another male, which he thought was more likely than in New Zealand because of its dense population.
