Abstract

Bark beetles have caused extensive damage to forests in central Sweden during the past decade, and the four-eyed spruce bark beetle, Polygraphus poligraphus, seems to be involved. However, its role in these bark beetle outbreaks is still not clear. The purpose of this study was to develop an efficient pheromone bait for P. poligraphus, which would make it possible to study the species more carefully and thereby contribute to protect exposed forests in an environmentally friendly way. Three field studies were conducted in 2015, 2016 and 2018 in Medelpad, county of Vasternorrland, Sweden. The pheromone of P. poligraphus, (-)-terpinen-4-ol, was tested at different release rates and in different enantiomeric purities, to find the most attractive formulation for the beetles. It was also tested in combination with racemic frontalin, a compound which has previously been shown to produce a synergistic effect together with (-)-terpinen-4-ol of low enantiomeric purity; 52% ee. Other compounds, chosen based on responses from electroantennographic studies, were also tested in an attempt to find additional attractants and repellents for P. poligraphus. The most attractive treatment tested was enantiomerically pure (-)-terpinen-4-ol (99% ee). When the enantiomeric purity was lower (50% ee), the trap catches was lowered to levels comparable to the catches for unbaited control traps. A strong synergistic effect with frontalin was observed for (-)-terpinen-4-ol of low enantiomeric purity (50% ee) but not for the enantiomerically pure compound (99% ee). The release rate of (-)-terpinen-4-ol (99% ee) was shown to be an important factor. For the combination of frontalin and (-)-terpinen-4-ol (50% ee), the attraction seemed strongest when (-)-terpinen-4-ol was released at a higher rate than frontalin. An interesting and novel result was that a repellent compound, alpha-terpineol, was identified in our studies. Our results from field studies and electroantennography recordings also indicate that (+)-terpinen-4-ol is a repellent for P. poligraphus.

Keywords

enantiomers; field study; frontalin; pheromone; synergism; terpinen-4-ol

Published in

Journal of Applied Entomology
2019, Volume: 143, number: 7, pages: 721-730
Publisher: WILEY

SLU Authors

• Schroeder, Martin

  • Department of Ecology, Swedish University of Agricultural Sciences
    

Associated SLU-program

SLU Plant Protection Network


UKÄ Subject classification

Ecology


Publication identifier

DOI: https://doi.org/10.1111/jen.12641

Permanent link to this page (URI)

https://res.slu.se/id/publ/101107