Ladybugs' Diet Guides Biocontrol Agent
By researching the diet of lady beetles, USDA scientists have learned more about the movement of these insects and how they may be beneficial in farm fields by eating crop pests.
Agricultural Research Service (ARS) entomologist Jonathan Lundgren at the agency's North Central Agricultural Research Laboratory in Brookings, S.D., and former ARS entomologist Michael Seagraves were part of a team of scientists that examined how a lady beetle's diet alters its feeding patterns and physiology.
Lady beetles are deployed as biological controls of insect pests like aphids and Colorado potato beetles. Understanding the feeding behavior of these important beneficial insects can help researchers find ways to effectively use the lady beetles as biocontrol agents.
In laboratory feeding tests, the researchers found that a lady beetle species 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, demonstrating that plant material provides key nutrients that aren’t available in prey-only diets. Thus, beetles that are fed mixed diets are often healthier that those fed only on prey.
According to Seagraves, all the tested lady beetles regularly consumed sugar-like nectar in soybean fields, even when it wasn't offered as a supplement. This research makes the case that sugar-feeding is very important for lady beetle populations in cropland and suggests a possible way to help maintain beneficial species in agroecosystems.