Posted on: 02 March, 2017
Author: Alexander P
D. brevicomis and D. pseudotsugae, both of which are attracted to frontalin, could be maintained by the terpenes 3-carene and camphene in the respective host species (Pitman and Vité 1970). Subsequent... D. brevicomis and D. pseudotsugae, both of which are attracted to frontalin, could be maintained by the terpenes 3-carene and camphene in the respective host species (Pitman and Vité 1970). Subsequently it was found that oz-pinene is interchangeable with camphene in the D. pseudotsugae attractant (Rudinsky et al. 1972a) and that myrcene is a superior terpene synergist for the D. brevicomis attractant (Bedard et al. 1969). Detailed examination of terpene composition in the host species of the different beetles revealed a number of specic criticisms to the situation hypothe- sized above. However, the most important criticism of this work is that pheromone specificity was assumed without being tested. It is not known, for example, that D. brevicomis and D. pseudotsugae are not cross attractive. In every published case in which cross attractiveness of Dendroctonus species a has been tested, beetles responded in a number that would have been predicted by the bouquet of compounds they are known to produce. D. pseudotsugae forced to bore in several factitious or occasional hosts were attractive to the ying population (Jantz and Rudinsky 1965; Chapman and Dyer 1969) according to http://sundowndivers.org/dr-cutlers-athena-pheromones/ D. ponderosae reportedly responds to D. brevlcamls boring in ponder-on pine (Pitman et al. 1968). There is no reason to believe that D. brevicomis would not be attracted to D. ponderoszze boring in ponderosa pine or in another host even though D. brevicomis cannot successfully attack certain species (Smith 1961, 1963, 1965). It seems clear that neither production nor reception of attractant compounds from both the beetle and the tree is sufficient to enforce reproductive isolation among many of the species of sympatric Dendroctonus. 9.3. Pheromone systems and reproductive isolation Role of pheromones Our knowledge of behavioral specificity in Trogoderma and Ips exceeds our under- standing of pheromone specicity. The reverse is true in Dendroctonus. The role of pheromone systems in maintaining reproductive isolation appears, at this early stage of the field, to be quite different in these genera. Pheromone systems effectively prevent interspecic insemination in Ips because sympatric species are not (or only minimally) cross attractive. These species may share some attractive compounds, as do I. paraconfusus and 1. calligraphus, but the bouquet is unique, and blocking or some other mechanism mediates against cross attractiveness (Wood et al. 1967; Renwick and Vité 1972). Pheromone systems per se appear not to isolate most T rogoderma and certain sympatric Dendroctonus such as D. brevicomis and D. ponderosae or D. rupennis and D. pseudotsugae. Synergism by specific terpenes may play a role in minimizing attraction between two Dendroctonus species which produce some of the same pheromones, but infest different hosts (as theorized by Pitman et al. 1969), although this hypothesis has never been tested. To the contrary, conspecific and nterspecific attraction between D. pseudotsugae and D. rufipennis (J antz and Rudinsky 1965; Chapman and Dyer 1969) prove that, in some cases, host species is of little consequence to pheromone attractiveness. Consequence of interspecific attraction Breeding experiments demonstrated reproductive isolation among all combinations of the Trogoderma species listed in table 9.1 (Beal and Spitler 1959; Strong and Arndt 1962). Only the reciprocal combination of T. granarium and T. glabrum produced brood, but these were totally sterile. Source: Free Articles from ArticlesFactory.com Alexander P is a blogger that studies pheromones. He is from Los Angeles, CA.