The introduced bark beetles Hylurgus ligniperda and Hylastes ater (Coleoptera: Scolytidae) in Chile: seasonal flight and effect of Pinus radiata log placement on colonization

The seasonal flight of Hylurgus ligniperda (Fabr.) and Hylastes ater (Paykull) and the effect of log placement in Pinus radiata D. Don plantations on colonization by these species in Chile are described. Seasonal flight activity was monitored with α-pinene and ethanol-baited traps at three sites and colonization synchrony with trap logs. In two experiments with individual logs and log decks, data were recorded on adults found under the logs, attacks on the bark surface, and adults beneath the bark of logs in three storage treatments: individual logs and log decks (1) touching the soil; (2) elevated above the soil; and (3) touching other logs (individual logs) or logs separated with spacers (log decks). Each treatment was replicated in a plantation and a clearcut. At San José (region IX) and Peña Blanca (region VIII), H. ligniperda flew primarily in spring and H. ater flew in spring and fall. At Brasil (region VIII), H. ligniperda and H. ater flew primarily in summer through fall. The flight of H. ligniperda was more synchronized with colonization of logs than was that of H. ater. The mean number of attacks was significantly higher on individual logs and log decks stored on the soil than on those elevated above the soil, and significantly higher in the clearcut than in the plantation. Mean numbers of adults beneath the bark did not vary significantly among individual-log treatments, but were significantly lower in the log decks separated by spacers. Logging during nondispersal periods (June–August in regions VIII–X) and storing log decks above the soil could reduce beetle colonization of newly cut logs. With this information, management of recently cut logs (harvesting, transport, and storage operations) could be scheduled and executed so as to reduce the risk of these species being introduced into log-importing countries.