On the specific attraction of the males of the six-toothed spruce bark beetle,Pityogenes chalcographus (L.) to a mixture of synthetic pheromones of the eight-toothed spruce bark beetle,Ips typographus (L.) (Coleoptera, Scolytidae)

Abstract

Summary. Traps containing a mixture of attractants for Ips typographus also caught other species of bark beetles. The numbers of Pityogenes chalcographus, Pityogenes conjunctus, and Trypodendron lineatum were too high to be interpreted as accidental captures. The males of the polygamous P_ chalcographus were specifically attracted, indicating that the L typographus pheromone or one of its components acts as a kairomone and primary attractant for the pioneering males of P. chalcographus. Key words. Attraction; bark beetles; Ips typographus; kairomone; Pityogenes chalcographus; population aggregation pheromone; Trypodendron lineatum.Colonization of host trees by bark beetles has been divided into four phases: dispersal, selection, concentration, and establishment ~. Dispersal begins with the emergence of the beetles from brood trees or overwintering sites in the ground and ends with a response to host stimuli and/or attractive pheromones, initiating the selection of a suitable host. This second phase ends with the landing on the tree and sustained feeding in the bark. The pioneering beetles are females in the case of the so-called monogamous bark beetles, but males in the case of the polygamous bark beetles. They initiate the concentration phase by emitting their specific population aggregation pheromone, which attracts both males and females and thus concentrates the population on one or a few suitable host trees.The polygamous bark beetles, Ips typographus (L.) and Pityogenes chalcographus (L.), swarm twice a year at about the same time 2. Both infest mainly wind blown, water-stressed, diseased or otherwise weakened spruce trees (Pieea spp., mainly Norway spruce, Picea abies). It is generally thought that such trees produce primary attractants that are missing or less concentrated in healthy spruce. These substances attract the pioneering males to suitable trees where each of them bores a hole into the bark and enlarges it to a nuptial chamber. By eating some of the bark the males take up oleoresin containing monoterpenes which are oxidized to one or several substances and excreted with the frass. These substances function as the specific secondary attractants for both males and females of their species 3. In the case of L typographus the main aggregation pheromone components are 2-methyl-3-buten-2-ol and (S)-cis-verbenol 4's. They are first excreted, whereas ipsdienol, another substance produced by the male beetle s , is excreted after the nuptial chamber has been excavated and 2-3 females have entered the gallery 7. The main component of the population aggregation pheromone of P. chalcographus is 2-ethyl-1,6-dioxaspiro(4,4) nonane s.European forest entomologists consider P. chalcographus a typical 'companion' of L typographus. But while the much larger L typographus prefers the thicker bark of the lower two thirds of the stems of more than 50-year-old spruce, P.ehalcographus prefers young spruce trees and/or the crown region, i.e. the upper third of the stems and the large branches of older trees, where the bar...

Exploiting fugitive resources: How long-lived is “fugitive”? Fallen trees are a long-lasting reward for Ips typographus (Coleoptera, Curculionidae, Scolytinae)

“…We thus probably overestimate the relative impact of intrinsic phloem decay as compared to inter-specific competition. Specifically, active avoidance by I. typographus of areas colonized by its main competitor, Pityogenes chalcographus, has been described (Benz et al, 1986;Byers, 1993;Hedgren, 2004). This latter species is also known to have a negative effect on the production of I. typographus and is observed on 38-89% of the available hosts (Eriksson et al, 2006;Komonen et al, 2011).…”

Primary attraction in host recognition of coniferous bark beetles and bark weevils (Col., Scolytidae and Curculionidae)

“…Aggregation pheromones elicit a very specific and often stronger attraction than do host odours, but the electrophysiological basis seems only partly clarified ( T P I M M E~S 1985). Even species not producing aggregation pheromones themselves are reported to respond to kairomones from other beetle species (e.g., HEDDEN et al 1976;WOOD 1982;KOHNLE 1985;BENZ et al 1986;BYERS 1989;T 0 M M E d S et al 1989;PHILLIPS 1990a, b). The bait billets in the present experiment were intentionally shielded from attack, but logs in the surroundings that could be attacked, would after the first attack (boring) result in an increase in the release of host volatiles and by that attractivity, a situation similar to and sometimes misinterpreted as secondary attraction, see discussion in TILLES et al (1986a) and.…”

SEMIOCHEMICAL-BASED COMMUNICATION IN INTERSPECIFIC INTERACTIONS BETWEEN IPS PINI (SAY) AND PITYOGENES KNECHTELI (SWAINE) (COLEOPTERA: SCOLYTIDAE) IN LODGEPOLE PINE

“…However, P. knechteli exploited the aggregation pheromone of I. pini to aid in host location (Figs. The male to female sex ratio for captured P. chalcographus was much higher than the natural sex ratio; mostly males were captured (Benz et al 1986;Zuber and Benz 1992). The relative response of male P. knechteli to I. pini males was higher than that of females, given a 1:5 sex ratio (Table 1).…”

“…The relative response of male P. knechteli to I. pini males was higher than that of females, given a 1:5 sex ratio (Table 1). Both species attack windthrown or weakened spruce trees, and resource partitioning could be mediated by the preference of the larger I. typographus for the thick bark of the lower two-thirds of the bole, and of P. chalcographus for younger trees or the crown region of larger trees (Benz et al 1986). There was a relatively greater response by male than female I. pini to P. knechteli males in one instance These results agree with those for the six-spined spruce bark beetle, Pityogenes chalcographus (L.), and the eight-spined spruce bark beetle, Ips typographus (L.), in European spruce trees (Picea spp.).…”