Effectiveness of Cedar Oil Products for Preventing Host Use by Ips avulsus (Eichhoff) (Coleoptera: Curculionidae) in a Modified Small-Bolt Assay

Abstract

Insecticide products based on cedar oil are readily available, but evaluations against pine bark beetles (Coleoptera: Curculionidae: Scolytinae) are lacking. In the southeastern U.S., the southern pine beetle, Dendroctonus frontalis Zimm, is the major bark beetle pest for which tree protectants are applied. However, Ips avulsus (Eichhoff) are more consistently available, are easily trapped and can attain pest status at times, making them an attractive option for the evaluation of certain tree protection products. In this study, we evaluated 2 commercial cedar oil products for their ability to prevent attack by I. avulsus on loblolly pine (Pinus taeda L.) bolts. The field method we deployed was an extension of a previously developed laboratory method in which small-bolts are treated with the product and provided a challenge by adult beetles. The new method used multiple-funnel traps baited with synthetic attractants to direct I. avulsus to test bolts. The method was successful in providing a challenge to treatments with I. avulsus, and resulted in neither product being consistently effective for preventing bolt utilization by this beetle. Although not considered effective in the majority of our trials, full-strength (neat) application of cedar oil product reduced bolt utilization by I. avulsus during winter trials (November and February), perhaps due to lower attack pressure from beetles. Evaluations at other times of the year (March through May), or that began > 0 days post-application, resulted in the products consistently failing to meet either of our efficacy criteria. Compared with competing insecticide products (e.g., those based on bifenthrin), the cedar oil products appear to be less effective, require more frequent reapplication and be more expensive.