Is it always a good idea for a plant to put on its best display of flowers. If you’re aiming to attract pollinators then it would seem odd to skulk in the shadows. However, a study by Fitch and Vandermeer published in the American Journal of Botany shows that light availability has a complex relationship with reproduction, due to differing relationships with mutualists and antagonists.

Fitch and Vandermeer based their study on Odontonema cuspidatum (mottled toothedthread or firespike), a plant native to Mexico, but invasive in the southern USA, Central and South America. Its long red tubular flowers are pollinated by hummingbirds. The birds have the narrow beaks necessary to reach deep into the flower to harvest the nectar. Insects do not, yet they’re not willing to leave the nectar to the birds. Two stingless bees, Trigona fulviventris and T. nigerrima, caught Fitch and Vandermeer’s attention.

These bees approach the flowers before they’re fully opened and perforate them at the base. They can then rob the flower of nectar before the hummingbird have a chance to grab it. This is excellent for the bees, but not so good for the flower. The authors report that a robbed flower is 40% less likely to set fruit than an unrobbed flower. While attracting pollinators is good, attracting robbers is a significant cost for a plant.