Greedy wasps damage flowers to steal nectar

 
Published: Tuesday 15 December 1992

CERTAIN wasps are inveterate nectar thieves. The wily insects sneak through the back door and loot nectar, damaging the flower and reducing chances of pollination and fruit formation (Current Science, Vol 26 No 10).

Insects help in pollination by acting as carriers of pollen grains, picking them up from one flower and depositing them on another as they buzz around looking for nectar. But scientists at Andhra University in Waltair found wasps of the Rynchium metallicum and Ropalidia species drilled holes at the base of flowers of the Vitex negundo plant to collect nectar. This not only provided a short cut for other insects such as ants and bees, but also threw the pollination system out of gear.

The researchers also found the wasps often attacked the buds before they opened. The plant flowers throughout the year. The buds open up in the morning and nectar is produced throughout the day, attracting about 20 species of insects.

Of 651 flowers observed, only 9 per cent of the perforated flowers were pollinated, compared to 96 per cent among non-perforated flowers. Only 7 per cent of 500 damaged flowers became fruits, compared to 76 per cent among undamaged flowers.

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