Influência de joaninhas adultas de hippodamia convergens no comportamento de pulgões schizaphis graminum e preferência alimentar das joaninhas adultas

Abstract

Ladybugs are natural enemies widely used in agriculture as allies in the control of insect pests, such as aphids and mealybugs. Their diet may consist solely of other insects or include a combination of foods, particularly in mass rearing in biofactories. The objective of this study was to evaluate the food preference of adult Hippodamia convergens between aphids (Schizaphis graminum), fall armyworms (Spodoptera frugiperda), and mealworms (Tenebrio molitor), as well as the behavior of Schizaphis graminum aphids. For the food preference test, an arena with a choice between two options was set up, featuring a central container and two side containers, where T1 contained aphids and T2 contained either armyworms or mealworms. To assess aphid behavior, an arena was set up with live mint plants; in T1, there were no ladybugs, while in T2, ladybugs were present. The number of colonies and the aphids’ movement on the plant were evaluated 24 and 72 hours after the start of the test. There was no statistically significant difference among the dietary treatments, indicating that the ladybugs adapted well to the food provided. The aphids exhibited avoidance behavior in the presence of ladybugs, which reduced and even inhibited their reproduction. It can be concluded that the use of alternative food sources in ladybug rearing is feasible; the adults showed no food preference among aphids, mealworms, and caterpillars. The presence of ladybugs or their chemical pheromones is beneficial for controlling their prey, demonstrating that the mere presence of ladybugs in the environment affects the prey’s behavior, significantly reducing their reproduction and movement.