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1 April, 2021

Motherhood makes crazy ants lazy

Removing queens from a colony of yellow crazy ants can trigger worker ants to produce offspring, and it makes them lazier and less able to protect their nest.


Removing queens from a colony of yellow crazy ants can trigger worker ants to produce offspring, and it makes them lazier and less able to protect their nest.

 And that could provide new opportunities for eradication, according to new research from James Cook University.

 JCU’s Associate Professor Lori Lach is an expert on the behaviour of the aggressive, rapidly spreading invasive ant species that kills small animals and leads to the destruction of crops. She coordinated a team of scientists working with 233 captive colonies of the ants.

 “We used laboratory experiments and genetic analyses to investigate the conditions for worker reproduction in the invasive Anoplolepis gracilipes (yellow crazy ant) and its potential cost to colony defence,” said Dr Pauline Lenancker, lead author of the paper.

 She said worker ants are all female, but unlike their queens, usually don’t produce offspring. Their role is to find food, look after the young and defend the nest. Male ants exist solely for reproduction and die shortly after mating.

 “Worker reproduction was recently reported for the first time in the yellow crazy ant, which is not something we would expect to see in an invasive species. The yellow crazy ant is the only invasive species where this has been seen.”

 “Our work subsequently showed yellow crazy ant workers preparing to mate were less aggressive and less likely to forage than normal workers,” said Dr Lach. 

 She said we would only expect worker reproduction to occur if it also carried benefits that outweighed the costs to the colony of having these ‘lazy’ workers.

 “The presence of a queen inhibits mating by workers, probably by means of pheromones. Removal or death of a queen triggered an increase in workers preparing to mate,” said Dr Lach. 

She said we know little about how new, unmated queens find males to mate with in this species, which does not have mating flights. If these virgin queens are able to mate with males produced by workers this may contribute to the yellow crazy ant success as an invasive species.

 “The more we understand about this very aggressive and damaging species the better we can tailor control measures to stop its spread,” said Dr Lach.

 The research was recently published in the journal Frontiers in Zoology and is freely available at https://rdcu.be/chhjI


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