Some plants may offer snacks to attract carnivorous insects that provide a defence against herbivorous attackers.


Billy Krimmel at the University of Califrnia, Davis, and Ian Pearse at Cornell University in Ithaca, New York, report that sticky, hair-like trichomes on common tarweed (Madia elegans) trap small insects. These may function as bait to attract predatory insects (pictured) that feast on caterpillars, which would damage the plant.

The authors carried out a field experiment in California, and found that adding dead fruitflies to plants increased the abundance of the predators that they surveyed by between 76% and 450%. Adding bait also reduced bud damage from the most common caterpillar in the ecosystem by 60%, and increased fruit production by 10%.

Ecol. Lett. (2012)