Cyclic Behavior of Lycorma delicatula (Insecta: Hemiptera: Fulgoridae) on Host Plants

Abstract

Lycorma delicatula is an invasive insect species in Korea, and its populations are increasing. It sucks plant sap and can cause withering of the whole trees. To prevent damage to fruit trees, it is important to determine the behavioral characteristics of L. delicatula. We monitored migration patterns and host plant preferences, from the egg mass on the tree bark, through egg hatching to egg laying. Most eggs hatched between 0500 h and 0800 h. The nymphs ascended trees until they reached the leaves. They often fell to the ground because of physical factors, such as wind, but then ascended the trees again on the upper sides of the branches. Their falling-ascending cycle became longer as their arolia developed. The host preference changed over the course of its growth, from a broad range of plant species at the early nymph stage to a few plant species, such as Ailanthus altissima at the adult stage. We summarize the life cycle behavior as follows. Initially, there is a short-term cycle of falling and ascending, which becomes longer as the nymphs age. The other cycle is a yearly cycle of host plant preferences, with broad host preference in the early nymph stage and a narrower host preference in the adult stage. Knowledge of this cyclic behavior can be used to prevent the rapid expansion of L. delicatula populations in orchards.