Non-host volatile blend optimization for forest protection against the European spruce bark beetle, Ips typographus

• Published in: PloS one 2014-01, Vol.9 (1), p.e85381
• Main Authors: Unelius, C Rikard, Schiebe, Christian, Bohman, Björn, Andersson, Martin N, Schlyter, Fredrik
• Format: Article
• Language: English
• Subjects: 1-Hexanol; Agriculture; Allelochemicals; Animals; Bark; Bark beetles; Beetles; Behavior, Animal - drug effects; Biologi; Biological Sciences; Biology; Chemistry; Coleoptera; Coleoptera - drug effects; Coleoptera - physiology; Curculionidae; Dose-Response Relationship, Drug; Ecological chemistry; Ecology; Ekologi; Ekologisk kemi; Experiments; Female; Forest protection; Forest Science; Forests; Hexanol; Host plants; Hostages; Ips typographus; Magnoliopsida - chemistry; Magnoliopsida - physiology; Male; Natural Sciences; Naturvetenskap; Optimization; Organic Chemistry; Organisk kemi; Pheromones; Physiological responses; Physiology; Plant Leaves - chemistry; Protection and preservation; Quality; Risk reduction; Scolytidae; Scolytinae; Skogsvetenskap; Smell - drug effects; Trees; Trees - chemistry; Verbenone; Volatile compounds; Volatile Organic Compounds - pharmacology; Volatiles; Weevils; Zoologi; Zoology
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0085381

Conifer feeding bark beetles (Coleoptera, Curculionidae, Scolytinae) pose a serious economic threat to forest production. Volatiles released by non-host angiosperm plants (so called non-host volatiles, NHV) have been shown to reduce the risk of attack by many bark beetle species, including the European spruce bark beetle, Ips typographus. However, the most active blend for I. typographus, containing three green leaf volatiles (GLVs) in addition to the key compounds trans-conophthorin (tC) and verbenone, has been considered too expensive for use in large-scale management. To lower the cost and improve the applicability of NHV, we aim to simplify the blend without compromising its anti-attractant potency. Since the key compound tC is expensive in pure form, we also tested a crude version: technical grade trans-conophthorin (T-tC). In another attempt to find a more cost effective substitute for tC, we evaluated a more readily synthesized analog: dehydro-conophthorin (DHC). Our results showed that 1-hexanol alone could replace the three-component GLV blend containing 1-hexanol, (3Z)-hexen-1-ol, and (2E)-hexen-1-ol. Furthermore, the release rate of tC could be reduced from 5 mg/day to 0.5 mg/day in a blend with 1-hexanol and (-)-verbenone without compromising the anti-attractant activity. We further show that T-tC was comparable with tC, whereas DHC was a less effective anti-attractant. DHC also elicited weaker physiological responses in the tC-responding olfactory receptor neuron class, providing a likely mechanistic explanation for its weaker anti-attractive effect. Our results suggest a blend consisting of (-)-verbenone, 1-hexanol and technical trans-conophthorin as a cost-efficient anti-attractant for forest protection against I. typographus.