Abstract:
The attack spatial pattern of the Douglas-fir beetle, Dendroctonus
pseudotsugae Hopkins was shown to be regular within a given subarea
of bark on its host, Pseudotsugae menziesii (Mirb.) Franco. Empirical
arguments were advanced which indicated the uniform spacing of attacks
was the result of a beetle controlled spacing mechanism dependent on the
production of 3-methyl-2-cyclohexen-l-one (MCH-one). Tests of selected
treatments in the field showed that virgin females in bolts, screened
in such a way that the closest another beetle could approach in any
direction was 1.24 cm, were more successful in eliciting attack
responses than any other treatment. Field tests also showed that
attacking beetles preferred to attack trees with rough bark texture
as smooth bark trees were less heavily infested.
