When we think about insects living in crops, we often picture pests, such as aphids, whiteflies, caterpillars or mites that damage plants and reduce production. However, agroecosystems are also home to many beneficial insects that help us control pests naturally. These are known as natural enemies: predators and parasitoids that, under the right conditions, can reduce the need for chemical treatments and contribute to more sustainable agriculture. Biological control is based on harnessing these natural interactions. Instead of relying only on insecticides, we can promote the presence and effectiveness of organisms that attack crop pests. Some predators feed directly on pests. Parasitoids, in contrast, lay their eggs inside or on insects, and their offspring develop at the expense of the pest. But there is one important idea that is often overlooked: natural enemies are not robots. They also need to feed. To search for pests, fly, survive and reproduce, many natural enemies require additional sources of energy and nutrients. Some of these food sources come from the plants themselves, such as floral nectar, extrafloral nectar, pollen or plant guttation. Others are associated with insects that feed on plants, such as honeydew produced by aphids, whiteflies or mealybugs. Together, these resources form what we could call the “food landscape” of the crop.
These food sources can make a real difference. A parasitoid with access to sugars lives longer and search more effectively for hosts. A predator with complementary resources may remain in the crop even when pest densities are still low. Less familiar resources, such as guttation, the small droplets that some plants exude from the edges of their leaves, can also provide sugars, amino acids and other nutrients that may be useful for different insects. Understanding who feeds on what, when, and with what consequences is essential for improving biological control. It is not only about releasing “good insects” into the field, but also about creating the conditions that allow them to survive, reproduce and perform their role more effectively. This may involve insectary plants, flower strips, habitat management, natural food resources or even supplementary foods designed to support specific natural enemies. Sustainable agriculture does not depend on a single solution. It requires combining ecological knowledge, crop management and effective tools. If we can better feed our natural allies, we may keep pest populations at lower levels, reduce our dependence on pesticides and produce food in a way that is more respectful of the environment. Put simply, if beneficial insects eat well, our crops, and we, benefit too.
Pablo Urbaneja-Bernat is a Ramón y Cajal researcher at Universitat Jaume I, Spain, where he works in the Plant Immunity and Biochemistry Group. His research focuses on biological control, insect nutritional ecology, and multitrophic plant–insect interactions in agroecosystems. He is particularly interested in how plant-derived food resources, including nectar, honeydew and guttation, shape the behavior, fitness and efficacy of natural enemies such as parasitoids and predators. His work aims to integrate ecological knowledge into sustainable pest management strategies, reducing reliance on chemical pesticides and improving the resilience of agricultural systems.