Whether they are trying to make sure crops keep growing or cattle continue eating, University of Florida Institute of Food and Agricultural Sciences researchers have a history of success using insects to control invasive plants and animals.
UF/IFAS entomologists and nematologists call the process biological control – essentially, bugs or nematodes eating bugs or invasive plants. It beats using chemicals to get rid of the insects preying on the fauna and flora because it means fewer chemicals in the environment and less costly ways for growers and landowners to control invasive plants.
Three non-native mole crickets came to Florida around 1900. These turf and forage grass pests scourged cattle ranchers until 1979, when the Mole Cricket Biological Control Project was established. UF/IFAS nematology researchers Khuong Nguyen and Grover Smart found, imported and named the nematodes, and entomology professors Howard Frank and Norman Leppla introduced the three biological control organisms (Steinernema nematode, Ormia fly and Larra wasp) into Florida until 2012. Leppla estimates the program saved $13.6 million in pest control costs.
Tropical Soda Apple
Native to South America, the fast growing weed known as tropical soda apple was introduced to Florida in 1988 and plagued rangelands and pasture in central and south Florida. Through the efforts of UF/IFAS entomologists, the leaf beetle Gratiana boliviana from Paraguay was released in Florida in 2003. This biological control program saves ranchers an estimated $11 million annually that would have been spent on chemical and mechanical control of this invasive weed.
Among his many projects, UF/IFAS entomology professor James Cuda works to control invasive aquatic plants, which take the place of desirable native flora. When that happens, native fish have less to eat, and some of them die from insufficient food and/or lack of oxygen.
Cuda and his team are developing an integrated approach to manage the aquatic weed hydrilla, using an insect — Cricotopus lebetis — a native fungus, and a newly developed herbicide. But hydrilla remains a problem because it grows in areas that are difficult to reach with treatments.
Although they remain in the federal approval stage, a South American psyllid and a thrips could help control the invasive Brazilian peppertree in places where it supplants critical habitat for many organisms, according to UF/IFAS and U.S. Department of Agriculture scientists.
In general, Brazilian peppertrees take over space where native plants should be. So, it impacts native animals and contributes to other invasive pest problems like the Diaprepes citrus root weevil that uses the tree for food.
The South Florida Water Management District estimates it spends $1.7 million per year to control the invasive tree.
Cuda also is working to develop a biological control for cogongrass, a weed that has invaded pastures throughout Florida, giving cattle less to eat. It was introduced into Florida in the 1930s and 1940s as a potential forage grass and soil stabilizer. Turns out, it’s a weedy pest. Cuda and his colleagues recently found a gall-forming midge (Orseolia javanica) they hope can help control cogongrass.