Wound response of loblolly and shortleaf pine attacked or reattacked by Dendroctonusfrontalis Zimmermann (Coleoptera: Scolytidae) or its fungal associate, Ceratocystisminor (Hedgecock) Hunt

Abstract

Loblolly, Pinustaeda L., and shortleaf, Pinusechinata Mill., pines respond to attack by the southern pine beetle (SPB), Dendroctonusfrontalis Zimmermann, or invasion by the SPB fungal associate, Ceratocystisminor (Hedgecock) Hunt, by forming a necrotic lesion around the wound site. This response was compared between trees that had no known prior experience with SPB or C. minor (naive trees) and trees that had been exposed to SPB or C. minor the previous year (experienced trees). No significant differences were observed in the average length of the lesions between experienced and naive trees in either pine species. However, the experienced loblolly pines had higher concentrations of inner bark monoterpenes than did the naive loblolly pines and the experienced shortleaf pines had a significantly different inner bark monoterpene composition compared with naive shortleaf pines during the June sample period. The monoterpene composition in unwounded tissue of experienced shortleaf pine closely resembled the observed monoterpene composition of lesion tissue at this time. The observed differences in inner bark monoterpenes following fungal or beetle exposure could render the trees less susceptible to later bark beetle attack for a period of time following the initial exposure.