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Last Updated: Wednesday, 24 January 2007, 01:26 GMT
Radio tags track wasp behaviour
The researchers looked at a species of paper wasp

Wasps fitted with minuscule radio tags have helped scientists shed light on the insects' behaviour.

Rather than just tending their home colonies, the worker wasps also buzzed into nearby relative-holding nests, helping raise the young, the team said.

The researchers believed the insects were boosting their chances of propagating their genes by nurturing relatives in multiple nests.

The Zoological Society of London (ZSL) study is published in Current Biology.

"Nest drifting, which is where individual insects move between different nests, has been described in a few different species of social insects, but it has always been a puzzle as to why they have done this," explained lead author Seirian Sumner of ZSL.

"It has also been very difficult to quantify - the standard way is to mark the wasps with paint and then carry out nest censuses - so we developed a new method."

To track the wasps, the team fitted the insects with Radio Frequency Identification (RFID) tags and placed sensors at the entrance of each nest to record their movements, in real time, in and out of the nests.

Dr Sumner said she got the idea from the Oyster card "touch in, touch out" system used on the London Underground.

Passing genes

The researchers, working in the tropics of Panama, looked at an extended colony of 33 nests belonging to a species of paper wasp called Polistes canadensis.

In each nest, they tagged every female worker (those in the colony responsible for nest maintenance, food gathering and care of the brood), fitting a total of 422 with the RFID tags.

A "staggering number", 56% of the population, were drifting from nest to nest, Dr Sumner told the BBC News website, many more than previous studies had estimated.

After further observations, the ZSL team ruled out that the wasps were lost, confused by their tags or trying to lay eggs in their neighbours' nests in a bout of social parasitism.

Instead, it found the wasps were helping to raise their relatives' young.

Worker wasps do not reproduce themselves, but by raising relatives - who share their genes - they can pass on genes indirectly, explained Dr Sumner.

"And these workers are gaining indirect fitness benefit by helping to raise relatives on lots of different nests rather just than their home nests."

This would be particularly crucial with wasps that face a high likelihood of getting their nests destroyed, such as the P. canadensis, she said.

"If you have just put all of your efforts into one nest and then that nest gets eaten, then all of this effort is lost and you haven't helped to pass on your genes," Dr Sumner said.

The researchers expect to find similar behaviour in other insect species.

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