Trapping failure leads to discovery of potent semiochemical repellent for the walnut twig beetle

Abstract

The walnut twig beetle, Pityophthorus juglandisBlackman, and its associated fungal pathogen that causes thousand cankers disease, currently threaten the viability of walnut trees across much of North America. During a 2011 assessment of seasonal flight patterns of P. juglandiswith yellow sticky traps baited with the male-produced aggregation pheromone component, 3-methyl-2-buten-1-ol, dramatically reduced catches were recorded when Tree Tanglefoot adhesive was used to coat the traps. In summer 2011, two trap adhesives were tested for potential repellency against P. juglandisin a field trapping bioassay. SuperQ extracts of volatiles from the most repellent adhesive were analyzed by gas chromatography–mass spectrometry, and limonene and α-pinene were identified as predominant components. In field-based, trapping experiments both enantiomers of limonene at a release rate of ~700 mg/d conferred 91–99% reduction in trap catches of P. juglandisto pheromone-baited traps. (+)- and (‒)-α-Pinene reduced trap catch by 40 and 53%, respectively, at the highest release rate tested. While a combination of R-(+)-limonene and (+)-α-pinene resulted in a 97% reduction in the number of P. juglandiscaught, the combination did not consistently result in greater flight trap catch reduction than individual limonene enantiomers. The repellent effect of limonene may be valuable in the development of a semiochemical-based tool for management of P. juglandisand thousand cankers disease.

Citation

Audley, Jackson P; Dallara, Paul L; Nelson, Lori J; Hamud, Shakeeb M; Bostock, Richard M; Seybold, Steven J. 2020. Trapping failure leads to discovery of potent semiochemical repellent for the walnut twig beetle. Journal of Economic Entomology. 113(6): 2772-2784. https://doi.org/10.1093/jee/toaa257.