Posted on: 02 March, 2017
Author: Alexander P
Learn about the best aggregation pheromone. For example, frass expelled from the galleries, and male paraconfusus guts lose attraction in proportion to the number of females in the gallery, with attra... Learn about the best aggregation pheromone. For example, frass expelled from the galleries, and male 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. calligraphus joined by three or more females quickly cease to synthesize the frass pheromone ipsdienol. Establishment 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 pheromonal 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 1957; 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 according to http://swankyseven.com/effective-pheromone-cologne-revealed/ Associated Pheromone insects In addition to scolytid beetles, which are the principal colonists in most of their hosts, a large complex of other species may join them. Some of these may compete for host tissue, or utilize areas of the host not inhabited by the scolytid species in question. Among such insects are other scolytid species, cerambycid and buprestid beetles and siricid woodwasps. In addition to other host feeders, there are many insect associates which are commensals, parasites (parasitoids) or predators of scolytids. Similarly, Heydenia unica Cook and Davis, a pteromalid parasite of Dendroctonus frorztalis respond in the field to oz-pinene, and response was not signicantly increased by combining known bark beetle phero- mones with ac-pinene (Camors and Payne 1972). Berisford and Franklin (1971) noted that three hymenopteran parasites of southern Ips species, Coeloides pissodes (Ashmead), Heydenia unica and Roptocerus eccoptogastri (Ratz.), oriented to in- fested trees in peak numbers 7 to 10 days after the peak Ips response, ‘suggesting a response to something other than aggregating pheromone. Finally, if the associated insects arrive during the period of aggregation phero- mone production, they could utilize them as kairomones (ch. 1). Brown et al. (1970) proposed the term kairomone and defined it asa transpecic chemical messenger, the adaptive benet of which falls on the recipient rather than on the emitter’. Thus, an associated predator, parasite or commensal of scolytid beetles which utilizes scolytid pheromones to locate a suitable host tree or beetle is, in fact, using them as kairomones. In host habitat nding a relatively small number of insect scolytid associates have definitely been shown to- exhibit a kairomone response to scolytid pheromones (table 8.2). Source: Free Articles from ArticlesFactory.com Alexander P is a blogger from Los Angeles who studies pheromones.