Parasitoid Increase During an Outbreak of a Native Herbivorous Insect Following Small-scale Amur Honeysuckle (Lonicera maackii) Removal

Abstract

Abstract. Recolonization by native species following removal of invasive plant species can often be uneven and lead to the rapid increase of one or a few native plant species. This can result in the formation of a significant resource pulse that may consequently affect populations of herbivorous species and their natural enemies. Here we present results from observations of parasitism rates during a localized outbreak of the Asimina webworm moth, Omphalocera munroei, a locally monophagous herbivore of the common paw-paw. Asimina triloba. This outbreak initiated from locations of increased understory growth of A. triloba, following the removal of Amur Honeysuckle (Lonicera maackii). Parasitism rates during the outbreak reached 50%, with higher parasitism rates observed in larvae collected at the end of the local outbreak relative to those the year following the peak of the outbreak. Parasitism rates remained high 3 y after the end of the local O. munroei outbreak, indicating >7 y of high parasitoid densities. O. munroei emerges late in the growing season, making it fairly inaccessible as a host or prey to many generalist predators/parasitoids, which emerge earlier the following year. This suggests the O. munroei outbreak potentially contributed to an increase in natural enemy pressure of other native species in the community.