International Institute of Tropical Agriculture / Flickr CC BY 2.0
Do you hate cruciferous vegetables like broccoli, Brussels sprouts, and radish? Their bitter taste comes from the pungent mustard oils produced by compounds called glucosinolates when the veggies are cut, chewed, or cooked. Many insect herbivores avoid these plants because of this defense mechanism too: when a plant is damaged by the insects nibbling on its tissues, it releases both glucosinolates and a catalytic enzyme which changes the glucosinolates to form new compounds toxic to the insect herbivores.
However, the whitefly Bemisia tabaci is a special case. Rather than avoiding cruciferous plants, whiteflies have specialized on them — establishing themselves as one the most notorious agricultural pest insects.
A recent study showed that whiteflies literally sugarcoat the mustard oils released by their plant meals to prevent themselves from being poisoned. This sap-sucking insect takes advantage of surplus sugar from the plant sap to detoxify the toxic chemicals, protecting themselves at no cost to their own resources.
Researchers say infestations of these insects can harm plants, and spread costly plant viruses. One type of whitefly was reported to have cost Texas and California $100 million in agricultural losses in just five years. Figuring how pest insects adapt to its host plant can help better control them in the future.