Verification of the interaction of the best pheromones and stridulation has been shown for Dendroctonus pseudotsugae (Rudinsky and Michael 1972). Males stridulate at or near the entrance to a female-o... Verification of the interaction of the best pheromones and stridulation has been shown for Dendroctonus pseudotsugae (Rudinsky and Michael 1972). Males stridulate at or near the entrance to a female-occupied gallery to produce a recog- nizable ‘courtship’ sound, distinguishable in oscilloscope traces from distress sounds. An identical sound is produced on exposure to frontalin, 3-methyl-2-cyc- lohexen-1-one (MCH) and transverbenol, all female-produced pheromones (table 8.1). A D. pseudotsugae female is able to mask her aggregation pheromone in response to the male’s stridulation, or to a non-stridulating male placed in her gallery (Rudinsky 1968, 1969, 1970; Rudinsky and Michael 1972). The pheromone mask stops within 9 to 14 min after males are removed from galleries (Rudinsky 1968) or after the stridulation sound is stopped (Rudinsky and Michael 1972). It does not mask the primary response to host volatiles and is limited to a small area around a gallery entrance. Thus, ying females can still respond to volatiles from unattacked regions of a host tree and males can respond to nearby unmated females (Rudinsky 1970)  Attack termination: It has recently been demonstrated that MCH is, in fact, the natural pheromone mask released by female D. pseudotsugae (Rudinsky et al. 1973). Since MCH inhibits the response of beetles in the eld to aggregation phero- mones (Rudinsky et al. 1972a), it is probably the attack termination factor responsible for inhibiting response to saturated hosts. Pheromone masks or response in- hibitors may occur in species other than D. pseudotsugae. Solitary virgin or mated Dypodendron lineatum produce secondary attraction, but the presence of males in the galleries greatly reduces the attraction, possibly because they can mask the aggregating pheromone (Nijholt 1970). Verbenone inhibits pheromone response in Dendroctonus frontalis (Renwick and Vité 1969) and D. brevicomis (Renwick and Vité 1970;Wood 1972). In part. termination of mass attack may be in response to decreasing production pheromones according to http://sundowndivers.org/feeling-anxious-sniff-this-pheromone/ For example, frass expelled from the galleries, and male Ips paraconfusus guts lose attraction in proportion to the number of females in the gallery, with attraction being completely lost after three or four females are present (Borden 1967). In support of this result, Vité et al. (1972) found that male I. calli- graphus joined by three or more females quickly cease to synthesize the frass pheromone ipsdienol. In order for reproduction to occur in most scolytid species, both sexes remain in the host and participate in a fairly intricate type of reproductive behavior (Swaine 1918', Reid 1958b; Wilkinson et al. 1967; Barr 1969; Borden 1969; Schmitz 1972). Although there is little or no experimental evidence, the environmental cues for establishment must include various host factors such as taste, smell, moisture and temperature, and must also include the presence of the opposite sex. This last factor is also little understood, but recognition probably occurs through chemical, acoustic and tactile communication, particularly in the dark reaches of a cryptic gallery. Whether or not various aggregation pheromones or other compounds serve as close-range recognition factors has not been investigated. Finally, if all factors are acceptable, the beetles of both sexes become physiologically tied to their hosts through degeneration of their ight muscles and consequent temporary inability to leave the host (Chapman l957; Reid 1958a; Hensen 1961; Atkins and Farris 1962; Bhakthan et al. 1970). Thus, the sequence is complete.* Beetles have emerged from their previous host or overwintering site and through a sequence of genetically controlled, behavioral events have successfully colonized a new host in which they will reproduce. With- out the employment of aggregation pheromones in host selection and concentration of the population, successful large scale colonization of this type would be improbable. Source: Free Articles from ArticlesFactory.com Alexander P is a blogger that studies pheromones. He is from Los Angeles.

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