Advantages of Understanding the Lady Beetle Diet

Understanding the feeding behavior of lady beetles will help agronomists develop cropping systems that best use these important beneficial insects as biological controls of insect pests, such as aphids and Colorado potato beetles. Agricultural Research Service entomologist Jonathan Lundgren at the North Central Agricultural Research Laboratory in Brookings, South Dakota, and former ARS entomologist Michael Seagraves were part of a team of ARS and university scientists that examined how lady beetle diets alter their feeding patterns and physiology. Appreciated for their ability to eat insect pests, lady beetles also consume nectar, pollen, and other plant tissue. Indeed, most beneficial predators eat both prey and non-prey foods, and understanding the factors that affect what they eat is important to using them in biological control of crop pests. The foods they consume determine where and when they can be found in a farm field and whether they decide to eat crop pests. Also, since many field crops are treated with insecticides, an important step in assessing the risk to beneficial species is to know how much insecticide these insects consume when they feed on plants. For laboratory feeding tests, the team chose a native lady beetle species, Coleomegilla maculata. The results of the tests reveal that this lady beetle consumes two to three times more plant tissue after being fed a prey-only diet than after being fed a mixed diet of prey and plant tissue. “This suggests that plant material is providing some key nutrients lacking in prey-only diets,” says Lundgren. “It is important to recognize that non-prey foods contain different nutrients from insect prey, and predators fed mixed diets are often more fit than those fed only prey.