Date of Graduation

12-2012

Document Type

Thesis

Degree Name

Master of Science in Entomology (MS)

Degree Level

Graduate

Department

Entomology

Advisor/Mentor

Stephen, Frederick M.

Committee Member

Steinkraus, Donald C.

Second Committee Member

Correll, James C.

Keywords

Biological sciences; Moisture content; Oviposition preferences; Shortleaf pine; Sirex noctilio

Abstract

The European woodwasp, Sirex noctilio F. (Hymenoptera: Siricidae) utilizes pine as its host during larval development. Females drill through pine bark to deposit eggs, a symbiotic fungus, Amylostereum, and phytotoxic mucus into the tree. In their native range, these insects are not viewed as primary pests because they attack dead or dying trees. Over the last century, this woodwasp has been accidentally introduced into several countries in the southern hemisphere. Some regions have incurred millions of dollars in damage to large plantations of the widely planted pine species, radiata pine (Pinus radiata D. Don). Sirex noctilio was discovered in northeastern United States and Canada in 2004. Prior studies have focused on damage done to pine stands in the southern hemisphere and, because those pines are not native, these studies may not be applicable to native pines in the U.S. The southeastern U.S. contains millions of hectares of possibly susceptible pine trees and, thus it is advisable to study the native Arkansas woodwasp, S. nigricornis F., (as a species with similar biology) in preparation for a possible invasion by its exotic counterpart. The objectives of this research were to 1) examine how shortleaf pine (Pinus echinata Mill.) logs (bolts) in moderate drought conditions of Arkansas lose moisture over time, and 2) determine oviposition preferences of Sirex nigricornis females in aging pine bolts. To complete these objectives, shortleaf pines were felled and moisture content was measured over a period of 45 days. Moisture content results were used to create parameters for oviposition choice experiments. After a cross-sectional cut was made, the most moisture loss occurs within 3-4 cm of bolt ends while the center of the bolt stays consistent during this time period. Females prefer to oviposit in recently cut bolts. Using these results, trap tree methods can be altered to create more efficient methods of siricid capture and laboratory rearing.

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