Plants That Eat Insects

Abstract

A small percentage of flowering plants, the carnivorous or insectivorous plants, capture and digest insects to obtain supplemental nutrients. The break-down products from the insects enable the plants to survive in nutrient-poor environments like swamps or bogs. Carnivorous plants use intricate chemistry to attract insects, trap them, and then finally digest them. Volatiles and patterns of anthocyanin pigments lure insects to modified leaves in the form of pitchers, as in Nepenthes, or capture them on sticky or slimy leaves, as in sundew or Venus flytraps. The insects are captured and then digested by enzymes. Nepenthes plants can be grown relatively easily in controlled set-ups, and the chemistry of their pitchers and fluids are well studied. The pitcher fluid is mostly water and contains specific enzymes, like chitinases. The leaves of other insectivorous plants like sundews (Drosera) and butterworts (Pinguicula), and the inner surfaces of Venus flytraps (Dionaea muscipula) are covered with mucilage, a gel-like substance consisting of glycoproteins. Mucilage secreted from sundews has been identified as a hydrogel. Recent biomedical research studies sundew mucilage as a potential biological adhesive in tissue engineering. Some insects have learned to go around the plants’ trapping mechanisms and feed on the prey captured by the plants. In another twist, some plants have flowers shaped like traps that hold insects captive for a while to do the pollination, then release them.