Masters Theses

Date of Award

8-2002

Degree Type

Thesis

Degree Name

Master of Science

Major

Entomology and Plant Pathology

Major Professor

Jerome F. Grant

Abstract

More than 100 species of woody and herbaceous plants are hosts of clearwing borers (Lepidoptera: Sesiidae). Injury to the living tissue of woody plants by clearwing larvae is a frequent problem in nurseries and home landscapes where damaged or stressed trees may be found. Much of their life cycle is spent beneath the bark of their host plant; thus, clearwings are considered one of the most difficult to control pests attacking trees and shrubs. Because of the importance of the clearwing complex and the damage larvae inflict to various species of woody and herbaceous plants grown for economic or aesthetic value, a two-year study was i�itiated in 2000 to determine species composition, assess influence of elevation on species composition, and assess seasonality of selected species of clearwing moths in urban and forest habitats in southeastern Tennessee. Seven locations in two geographically distinct areas of the state were selected for monitoring, including five urban habitats in Hamilton County, Tennessee, and two forest habitats in the Great Smoky Mountains National Park (GSMNP). During 2000 and 2001, 13 species, representing five genera, of adult male clearwing moths (n=18,012) were collected in pheromone-baited traps (17.4 mg 97/3 z, z-3, 13 C19 acetate/ e, e-3 13 C18 acetate 91% purity) at seven sites in southeastern Tennessee. The peachtree borer, Synanthedon exitiosa (Say), and lilac/ash borer, Podosesia syringae (Harris), were the two most commonly collected species (comprising 86.49 and 10.24%, respectively, of all adult moths). An oak borer, Paranthrene simulans (Grote), was more abundant in 2000 (n=339) than in 2001 (n=8), supporting other studies that demonstrate that P. simulans has a two-year life cycle with primary emergence in odd-numbered years. In general, lilac borer was the first species to appear in both habitats and emerged from early April to mid-July while peachtree borer generally did not emerge until late May, but remained active longer than lilac borer (mid-October). Species composition and the influence of elevation on seasonality of the two most abundant species (lilac borer and peachtree borer) were assessed for 2000 and 2001. Among all combined urban habitats, elevation significantly influenced densities of adult lilac borers (r2 = 0.67; F = 4.28; df = 2, 6; p=0.0699) and peachtree borers (r2 = 0.80; F = 12.46; df = 2, 6; p=0.0073). For both species, densities were significantly greater (ca. 1.4x - 2.3x) at the low elevation than at the moderate or high elevations. However, no significant differences were detected between the moderate or high elevations. In general, densities of peachtree borer and lilac borer were lowest at the high elevation. Data from this research suggest temperature changes among elevations may influence populations of peachtree borer and lilac borer adults. Because these differences in population densities were detected at sites close together in a geographically similar area, predictive flight phenologies of clearwing moths should be adjusted to consider elevational differences within a region or area. Additionally, continued monitoring of clearwing moths in urban and forest habitats can lead to a better understanding of emergence and species composition. This information may result in better timing of pesticide applications or other practices that support an integrated pest management approach to clearwing borer control.

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