J. A. A. Renwick

Population aggregating pheromone in the bark beetle, Ips grandicollis☆

Abstract Males and females of the bark beetle, Ips grandicollis , aggregate on host material in response to 2-methyl-6-methylene-7-octen-4-ol, a pheromone characteristic for five-spined Ips species. This compound is produced by the male beetle upon feeding in the phloem tissue of suitable pine trees. Other compounds such as trans -verbenol and host terpenes may cause occasional response to pines infested by other bark beetle species.

Oxidation products of pinene in the bark beetle, Dendroctonus frontalis☆

Abstract Southern pine beetles were collected as they emerged from infested pine bolts and exposed in Petri dishes to α- and β-pinene for 20 hr. Changes in the volatile contents of the beetles hindguts were detected by gas chromatography, and previously unidentified components were characterized by mass, i.r., and n.m.r. spectroscopy. A prominent compound in hindguts of both sexes before and after treatment was identified as myrtenol, and a less conspicuous, male-specific compound proved to be myrtenal. Upon exposure to α-pinene, males produced cis- and trans-verbenol, and 4-methyl-2-pentanol was found in both sexes. Compounds present after treatment with β-pinene vapour were identified as trans-pinocarveol in both sexes, and pinocarvone in the males.

Pheromones and host volatiles that govern aggregation of the six-spined engraver beetle, Ips calligraphus.

Abstract Both males and females of Ips calligraphus produce cis- and trans-verbenol upon feeding in suitable pine phloem, but only the males produce 2-methyl-6-methylene-2,7-octadien-4-ol (ipsdienol). They produce little or no 2-methyl-6-methylene-7-octen-4-ol (ipsenol), the aggregating pheromone of the sympatric engraver beetle, Ips grandicollis. The colonization of southern pines by I. calligraphus is guided by the combination of ipsdienol and cis-verbenol, and the attraction is enhanced by host volatiles. Field tests using traps baited with synthetic pheromones were successful in duplicating the phenomenon of mass aggregation.

The aggregation pheromone system of a Dendroctonus bark beetle in Guatemala

Abstract Analysis of the volatile contents of hindguts from a Dendroctonus bark beetle in Guatemala indicated distinct differences from those of D. frontalis, which it resembles morphologically. The major compound in emergent males, most of which disappears during initial attack of host trees (Pinus maximinoi), was identified as 1-phenylethanol. During initial attack females produce frontalin and trans-verbenol, males produce myrtenol, and both sexes produce 1-heptanol and 2-heptanol. Synthetic frontalin attracted predominantly males to small traps, but the use of larger trapping surfaces increased the proportion of females caught. The heptanols, as well as 1-phenylethanol, apparently had some regulatory effect on the response to frontalin, but myrtenol and trans-verbenol were inactive. The results suggest that frontalin is the key compound responsible for the aggregation of this species, but the response-regulating mechanism differs from that of D. frontalis.