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Wasps queue for top job

11 May 2006

Scientists at UCL (University College London) have discovered that even wasps are driven by their status.

The study, published today in Nature, shows that lower-ranked female wasps work harder to help their queen than those higher up the chain because they have less to lose, and consequently are prepared to take more risks and wear themselves out.

The study, funded by the Natural Environment Research Council (NERC), reveals that those higher up the chain and therefore with a greater chance of being the next in line to breed are much lazier than their lower-ranked nest-mates: rather than use up their energy in foraging to feed the queen's larvae, high-rankers sit tight on the nest and wait for their chance to become queen themselves.

Dr Jeremy Field, UCL Biology, said, "Helpers wait peacefully in an age-based queue to inherit the prize of being the queen or breeder in the group. The oldest female almost always becomes the next breeder. The wasps in this queue face a fundamental trade-off: by working harder, they help the group as a whole and as a result indirectly benefit themselves, but they simultaneously decrease their own future survival and fecundity because helping is costly. It involves energy-expensive flight to forage for food, and leaving the nest is dangerous. We have found that the brighter the individual wasp's future, the less likely it is to take risks by leaving the safety of its nest to forage for food."

The defining feature of eusocial animals - including insects like bees, ants and wasps, and vertebrates like meerkats and the naked mole rat - is that some individuals forgo their own reproduction to help rear the offspring of others. In hover wasps, helpers spend between 0 per cent and 95 per cent of their time foraging to feed the queen's larvae. Previous scientific thinking indicated that the variation in help given might be proportional to genetic relatedness. Those less closely related to the queen would help out less. This new study, however, shows that more distantly related wasps aren't in fact lazier.

Instead, the team led by Dr Field, found that it is the likelihood of future reproduction that primarily determines a wasp's behaviour - the more likely they are to spawn their own young in the future, the lazier they become.

The tests were carried out on the non-aggressive tropical hairy-faced hover wasp - Liostenogaster flavolineata. Both the wasp's rank and the size of the group were manipulated to show how these variables affected the amount of help each individual contributed to the group. The team changed the position of individual wasps in the social hierarchy by removing higher ranked, older wasps, thus promoting their younger relatives.

Regardless of age, a wasp's contribution to feeding the queen's young depended only on its position in the queue to inherit queenship. Lower-ranked helpers, and helpers in smaller groups, worked hardest.

Further information

Alex Brew
UCL press officer
Tel: 020 7679 9726 or 07747 565 056 out-of-hours

NERC Press Office
Natural Environment Research Council
Polaris House, North Star Avenue
Swindon, SN2 1EU
Tel: 01793 411561
Mob: 07917 557215

Notes

1. 'Future fitness and helping in social queues' will appear online in Nature on 10th May 2006 at 6pm UK time. The paper authors are: Dr Jeremy Field, Dr Adam Cronin & Dr Catherine Bridge

2. Pictures of the wasps, with identification tagging, and pictures of the nests studied, are available.

3. Founded in 1826, UCL was the first English university established after Oxford and Cambridge, the first to admit students regardless of race, class, religion or gender, and the first to provide systematic teaching of law, architecture and medicine. In the government's most recent Research Assessment Exercise, 59 UCL departments achieved top ratings of 5* and 5, indicating research quality of international excellence.

4. UCL is the fourth-ranked UK university in the 2005 league table of the top 500 world universities produced by the Shanghai Jiao Tong University. UCL alumni include Mahatma Gandhi (Laws 1889, Indian political and spiritual leader); Jonathan Dimbleby (Philosophy 1969, writer and television presenter); Junichiro Koizumi (Economics 1969, Prime Minister of Japan); Lord Woolf (Laws 1954 - Lord Chief Justice of England & Wales), Alexander Graham Bell (Phonetics 1860s - inventor of the telephone), and members of the band Coldplay.

5. NERC is one of the UK's research councils. It uses a budget of about £350m a year to fund and carry out impartial scientific research in the sciences of the environment. NERC trains the next generation of independent environmental scientists. It is addressing some of the key questions facing mankind, such as global warming, renewable energy and sustainable economic development.

Press release: 27/06

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