Wasps always win fight for food with ants

Washington: Scientists have found that wasps always win the fight for food while competing with ants – by picking up their rivals, flying off and dropping them at a distance from the food.

Analysing videos taken at bait stations, a team, led by Dr Phil Lester and Julien Grangier of Victoria University, says that for the ants the experience is the human equivalent of being thrown up to half the length of a football field.

The ants are not physically hurt but appear stunned by the drop and often do not return to the bait station.

In fact, the wasp, Vespula vulgaris, which is on the list of the world`s 100 worst invasive species, when competing for food, dominate just about every animal except native ants, the `Biology Letters` journal reported.

"Wasps seem to hear ants `talking`. They have nerves in their antennae that pick up pheromones or communication chemicals given out by the ants. So it could be the foraging ants that bring wasps to the food resource. Once there, they adjust their behaviour according to the level of competition imposed by these ants.

"Despite being 200 times smaller, the ants are able to hold their own by rushing at the wasps, spraying them with acid and biting them. Eventually the wasps get so angry they pick up the ant, take it away and return to eat the food.

"The strategy works. It`s giving the wasp access to resources it wouldn`t otherwise have," said Dr Lester.

Grangier added: "To the best of our knowledge this behaviour has never been observed before. Our results suggest these insects can assess the degree and type of competition they are facing and adapt their behaviour accordingly.

"It`s a new interaction between a native and an invasive species and a wonderful example of behavioural plasticity.