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

Abstract

The objective of this chapter is to determine whether the interaction between the invasive tachinid fly C. concinnata and three native Lepidopteran hosts might be altered in early successional habitat maintained by vegetation management along electric transmission line rights-of-way (ROW).Management practices that maintain habitats in an early successional stage are beneficial for a number of species of butterflies and moths (Lepidoptera). These benefits have been viewed primarily 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 natural enemies is an aspect not previously addressed. Such amendment may enhance larval survival by disrupting the foraging behaviors of natural enemies. Of particular interest are the effects of vegetation management on an abundant and important invasive species, the exotic tachinid (Diptera) parasitoid Compsitura concinnata. This species has been implicated in the population declines of several native Lepidoptera. To quantify this potential effect, this chapter focuses on three species of moths on an electrical transmission line running adjacent to and through Cape Cod National Seashore, MA. It also quantifies mortality from C. concinnata in experimental populations of these species, and a third species Antheraea polyphemus deployed on open growing young oaks on a managed electric transmission line ROW and on the same host plants in adjoining mature forest. Parasitism of all three species was significantly reduced within the ROW habitat. The patchy nature of the early successional habitat, characteristic of managed ROW, may disrupt the search efficiency of this parasitoid, creating enemy-reduced space for these species of Lepidoptera.