When there’s something strange in the neighborhood, who you gonna call? Who knew even plants have to ask themselves that question. Okay, I know I am mixing my movie references, but trust me, it works. Believe it or not, plants are also in need of a helping hand from time to time, like when an insect pest is invading, but who do they call and how? So glad you asked.
One answer can be seen in the actions of certain corn, cotton and tobacco plants, though the story is not a unique one. These plants are often in danger of being eaten by caterpillars, very hungry caterpillars, like the corn earworm and tobacco
budworm. The plants, however, are not defenseless and destined to end life as an all-you-can-eat buffet. These plants have unlikely insect allies to call upon in the form of parasitic wasps. When the caterpillars begin to feast, the plants will send out a chemical distress signal that alerts nearby parasitic wasps that just happen to want to lay their eggs in those same hungry caterpillars. Eggs hatch, and wasp larvae feast on the caterpillars from the inside out (eww or cool, depending on your penchant for the gross but fascinating side of nature). Pest eliminated, plant happy.
I know, I know, some (or many) of you are saying that this is not an actual call for help being sent out by the plant. It is more a natural response to being
bitten by the caterpillar that the wasp has evolved to pay attention to. But isn’t evolution so cool?!? And, some studies even suggest that the chemical signal sent out by a plant changes with different caterpillars so that the wasps can hone in on preferred hosts.
Humans are paying close attention to all of this interaction in the hopes of developing targeted, environmentally friendly pest management processes, and, let’s face it, just because it is so darn cool!