Mini-seedlings of Picea abies are less attacked by Hylobius abietis than conventional ones: Is plant chemistry the explanation?
Abstract:The pine weevil, Hylobius abietis (L.), is a major pest in conifer reforestation areas in the Palaearctic region. Size and chemistry of the seedlings may explain the damage rates in plantations. The performance of 10-week containerized seedlings (mini-seedlings) was compared with 1-year-old conventional seedlings of Norway spruce, Picea abies (L.), in a field experiment in central Sweden. After 2 years the weevil damage was lower for the mini-seedlings than for the conventional seedlings (3.5 vs 55%). After 3 years, the overall survival was 82 and 75%, respectively. Weevil damage was the main cause of mortality for conventional seedlings, whereas mini-seedlings mainly died from drought. Volatiles of the two seedling types were compared by solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). Unwounded mini-seedlings and conventional seedlings differed in their compositions of monoterpenes and sesquiterpenes. Mini-seedlings mainly emitted limonene, known to be repellent to the pine weevil. When wounded, green leaf volatiles were released by mini-seedlings while the pine weevil attractant α-pinene was released by conventional seedlings. Volatiles may partly explain the mini-seedlings' resistance against weevil attack. Further studies are needed to clarify how long this mini-seedling effect remains.
Document Type: Research Article
Affiliations: 1: KTH, School of Chemical Science and Engineering, Organic Chemistry, Ecological Chemistry Group, Stockholm, Sweden 2: School of Industrial Technology and Management, Dalarna University, Borlange, Sweden 3: Department of Entomology, Swedish University of Agricultural Sciences, Uppsala, Sweden
Publication date: August 1, 2008