Several plant species produce a large proportion of fruits with no seeds. Many scientists, including Charles Darwin, have wondered whether this odd habit has a useful function. Now a researcher in Spain has found that, in at least one species with some seedless fruits, the fruit with seeds suffer fewer attacks by insects (Evolutionary Ecology, vol 7, p 357).
Anna Traveset of Estacion Biologica de Donana in Seville studied Pistacia terebinthus, a Mediterranean shrub which produces small fruits about 7 millimetres long and 6 millimetres wide. At the end of June, when the bushes produce their new fruits, wasps lay one egg in each Pistacia fruit they find. The larvae of the wasps - Megastigmus pistaciae and Sycophila sp. - live, feed and pupate inside the seeds of the fruits, finally emerging to mate, lay eggs and repeat the cycle.
Traveset found that if a plant had some fruits without ...
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