Female white pine cone beetles,Conophthorus coniperda, attacking second-year cones of eastern white pine,Pinus strobus L., produced a sex-specific pheromone that attracted conspecific males in laboratory bioassays and to field traps. Beetle response was enhanced by host monoterpenes. The female-produced compound was identified in volatiles collected on Porapak Q and in hindgut extracts as (+)-trans-pityol, (2R,5S)-(+)-2-(1-hydroxy-1-methylethyl)-5-methyltetrahydrofuran. Males and females produced and released the (E)-(-)-spiroacetal, (5S,7S)-(-)-7-methyl-1,6-dioxaspiro[4.5]decane, which was not an attractant for either sex, but acted as a repellent for males. Porapak Q-trapped volatiles from both sexes contained (+)-trans-pinocarveol and (-)-myrtenol. In addition, hindgut extracts of females containedtrans-verbenol, while males had pinocarvone and verbenone. Work in Georgia and Canada confirmed that the same isomers of pityol and spiroacetal are present in two distinct and widely separated populations ofC. coniperda.

A randomized complete block experiment was performed to measure the effect of prescribed, dormant-season burns of three different levels of severity (measured as fuel consumption and soil surface heating) on subsequent insect infestation and mortality of mature longleaf pine (Pinus palustris Mill.). Multiple-funnel traps baited with a low release rate of turpentine and ethanol were used to monitor activity of certain coniferophagous beetles. Non-aggressive species, including the root beetles Hylastes salebrosus Eichhoff and H. tenuis Eichhoff, the ambrosia beetle Xyleborus pubescens Zimmermann, the reproduction weevil Pachylobius picivorus (Germar), and buprestid borers, were attracted to burned plots in numbers that correlated positively with burn severity. Beetle attraction to burned sites was greatest in the first weeks post-burn and disappeared by the second year. Two potential tree-killing bark beetles, Dendroctonus terebrans (Olivier) and Ips grandicollis (Eichhoff), were trapped in significant numbers but exhibited no attraction to burned plots. Tree mortality correlated significantly with the severity of the burns and amounted to 5% of stems in the hottest burn treatment after 3 years. The majority of the mortality was observed in the second and third years post-burn. Attacks of Ips and Dendroctonus bark beetles were apparent on nearly all dead or dying trees, and evidence suggested that root pathogens may have contributed to tree susceptibility to beetle attack and mortality. Our data indicate that selection of burn regimes that reduce or eliminate consumption of duff (e.g., favoring heading fires over backing fires) could significantly reduce mortality of longleaf pine managed for long rotations. Published by Elsevier B.V.

No abstract

Hindgut volatiles from attacking, unmated males ofIps avulsus, I. calligraphus, I. grandicollis, andI. piniwere analyzed by combined gas chromatography and mass spectrometry. Based on the quantitative identifications of hindguts and subsequent individual aerations, baits were formulated and a combined species-specific subtractive field bioassay was set up for the four bark beetle species. The bioassays were subtractive for the compounds identified in the hindgut analysis of each species, and volatiles identified in sympatric species were added as potential inhibitors alone and in combination. The trap catches from this bioassay revealed strong interspecific inhibition. The subtractive assays showed thatI. grandicollisandI. calligraphusshare (–)-(4S)-cis-verbenol as one pheromone component, while their second, synergistic pheromone component, (–)-(S)-ipsenol inI. grandicollisand (±)-ipsdienol inI. calligraphus, acts as an interspecific inhibitor to the other species.I. avulsusandI. piniwere found to have very similar production of hindgut volatiles, and both use ipsdienol and lanierone as synergistic pheromone components. No beetle-produced interspecific inhibitor was identified between these two species. Lanierone was found to be an interspecific inhibitor for bothI. calligraphusandI. grandicollis.

No abstract

Intensive forest management practices have been shown to increase tree growth and shorten rotation time. However, they may also lead to an increased need for insect pest management because of higher infestation levels and lower action thresholds. To investigate the relationship between intensive management practices and insect infestation, maximum growth potential studies of loblolly pine, Pinus taeda L., were conducted over 4 yr using a hierarchy of cultural treatments. The treatments were herbaceous weed control (H), H + irrigation (I), H + I + fertilizer (F), and H + I + F + pest control (P). These treatments were monitored for differences in growth and insect infestation levels related to the increasing management intensities. The Nantucket pine tip moth, Rhyacionia frustrana (Comstock), was consistently found infesting study trees. In the third field season, the H + I + F + P treatment had significantly more southern pine coneworm, Dioryctria amatella (Hulst), attacks than the H and H + I treatments. There were significant differences in volume index (D2H) among all treatments after each of the four growing seasons. This study indicated that tree fertilization can increase coneworm infestation and demonstrated that tip moth management can improve tree growth initially. Future measurements will determine if the growth gains from tip moth management are transitory or sustainable.

No abstract

Different enantiomeric ratios and elution rates of the inhibitor pheromones verbenone and racemic endo-brevicomin were evaluated for their effects on the numerical response of the southern pine beetle, Dendroctonusfrontalis Zimm., to attractant-baited traps. Enantiomeric ratios and elution rates of verbenone were important factors in inhibiting response of male D. frontalis. Deterrence was most effective for enantiomeric ratios of verbenone containing 34 and 50% of the (+) enantiomer. Using a 34% (+): 66% (−) mixture of verbenone, the number of male D. frontalis captured in attractant-baited traps declined as elution rates increased from 4.2 to 12.5 mg/h. None of the enantiomeric ratios or elution rates of verbenone tested consistently influenced female response. endo-Brevicomin added to attractant-baited traps reduced catches of male D. frontalis, but did not significantly reduce catches further when added to traps also emitting verbenone. Female catches were not reduced significantly by the presence of endo-brevicomin. Numerical responses of the predatory beetle Thanasimusdubius Fab. are generally unaffected by the presence of verbenone alone or in combination with endo-brevicomin.