PHEROMONE PRODUCTION BY THE PINE ENGRAVER IPS-PINI FOLLOWING FLIGHT AND STARVATION

Flown and unflown males of the pine engraver, Ips pini (Say) (Coleoptera: Scolytidae), exposed to 0.1 μl of the pheromone precursor myrcene in a 3.5 ml vial, produced similar amounts of the pheromone ipsdienol; the production of ipsdienol was not correlated with the duration of flight preceding myrcene exposure. In contrast, exposure of flown or starved males to a larger 0.4 μl dose of myrcene, which apparently "challenged" their metabolic capacity, revealed a reduction of ipsdienol production in relation to the loss of body weight during flight or starvation. A declining capacity during dispersal flight to metabolize myrcene and possibly other monoterpenes could alone or in concert with lipid oxidation be part of an internal feedback system that induces a reversal from dispersal to host selection behaviour. Alternatively, it may reduce the spectrum of suitable hosts to pine trees of moderate resin pressure, as naturally preferred for colonization by I. pini. © 1990.