Transmission Line Rights-of-Way as Enemy-Reduced Space for Moths (Lepidoptera)

摘要

Management practices that maintain habitats in an early successional stage are beneficial for anumber of species of butterflies and moths (Lepidoptera). These benefits have been viewed pri-marily as enhancement of habitat for larval host plants and/or nectar sources used by adults.The potential for habitat management to alter interactions between Lepidoptera and their naturalenemies is an aspect not previously addressed. Such amendment may enhance larval survival bydisrupting the foraging behaviors of natural enemies. Of particular interest are the effects of vege-tation management on an abundant and important invasive species, the exotic tachinid (Diptera)parasitoid Compsilura concinnata. This species has been implicated in the population declinesof several native Lepidoptera. To quantify this potential effect, we focused on three species ofmoths on an electrical transmission line running adjacent to and through Cape Cod NationalSeashore, MA. Two of the species, barrens buck moth (Hemdeuca maia) and yellow-necked cater-pillar (Datana ministra), have suffered substantive population declines in New England in recentyears and were more abundant in rights-of-way (ROW) habitat than in any other habitat assessedin the study area. We quantified mortality from C. concinnata in experimental populations of thesespecies, and a third species Antheraea polyphemus deployed on open growing young oaks on amanaged electric transmission line ROW and on the same host plants in adjoining mature for-est. Parasitism of all three species was significantly reduced within the ROW habitat. The patchynature of the early successiorl habitat, characteristic of managed ROW, may disrupt the searchefficiency of this parasitoid, creating enemy-reduced space for these species of Lepidoptera.