Significance of Wood Terpenoids in the Resistance of Scots Pine Provenances Against the Old House Borer, Hylotrupes bajulus, and Brown-Rot Fungus, Coniophora puteana

Abstract

We tested how terpenoid (i.e., monoterpenes and resin acids) composition and concentration in wood affects resistance against wood-borers and decaying fungi. Scots pine (Pinus sylvestris) wood from nine provenances having variable terpenoid profiles was studied against the old house borer, Hylotrupes bajulus, and the decay fungus, Coniophora puteana. Provenances represented a 1200-km N-S transect from Estonia to northern Finland, but they were all cultivated for 7 years in the same nursery field, in central Finland. Mean relative growth rate (MRGR) of small H. hajulus larvae positively correlated with the total monoterpene concentration of wood, and feeding was associated with high proportion of levopimaric+palustric acid in wood. Provenance did not affect the MRGR of small or big larvae, but big larvae consumed more wood and produced more frass on the northern Ylitornio trees than on the southern Rakvere and Ruokolahti trees. Low beta-pinene and total monoterpene concentration and low beta: alpha-pinene ratio in wood were all associated with a high number of eggs. The most northern Muonio provenance was the most favored as an oviposition site, differing significantly from Saaremaa, Tenhola, and Suomussalmi. Wood from Saaremaa, Tenhola, Ruokolahti, and Suomussalmi provenance was most resistant against decay fungus, differing significantly from that of Kinnula provenance. However, decay resistance was not clearly associated with the concentrations of wood terpenoids. These results suggest that monoterpene composition of wood affects resistance against wood-boring Cerambycid beetles, but resistance against wood-decaying fungi is not as clearly associated with wood terpenoids.

Larvicidal activities of some bark and wood extracts against wood-damaging insects

“…In addition, a negative-directional relationship was determined between the mass losses and death rates of larvae. Similar results were found in some studies using botanical extracts (Nerg et al 2004). …”

Resistance of Scots pine wood to Brown-rot fungi after long-term forest fertilization

“…In other Pinus species phenolics are found to increase heartwood decay resistance (Hart and Shrimpton 1979). The role of resin acids in the decay resistance of Scots pine wood seemed to be minor in Scots pine as also shown in earlier studies Nerg et al 2004;Venäläinen et al 2004). However, according to the present results resin acids might be more important in wood natural durability than the monoterpenes.…”

Diterpene resin acids in conifers

“…Pine sawfly larvae (Neodiprion sertifer) appear negatively affected physiologically by resin acids but are better protected from predators on trees containing high resin levels (Bjö rkman and Gref, 1993;Saikkonen et al, 1995;Bjö rkman et al, 1997;Larsson et al, 2000). The old house borer (Hylotrupes bajulus) actually feeds more intensively on wood containing higher concentrations of levopimaric acid and palustric acid while the brown-rot fungus (Coniophora puteana) is unaffected by differences in diterpene resin acid quantities (Nerg et al, 2004).…”