Breeding performance of the second generation in some bivoltine populations of Ips typographus (Coleoptera Curculionidae) in the south-eastern Alps.

The spruce bark beetle, Ips typographus, is one of the most extensively studied European forest pests. Gaps exist in the knowledge about second generation breeding performance in bivoltine populations. In this study, the breeding performance of the second generation was evaluated in three bivoltine populations of I. typographus in the SE Alps. Length of the maternal galleries (from 40.5 to 44.8 mm), population growth rate (PGR; from 0.7 to 3.6), and emerged adults per m2 (from 669 to 1,570 insects/m2) varied among populations and were negatively correlated with bark colonisation density. Pheromone traps set up in the three investigated forests differed in the number of trapped beetles, with mean captures ranging between 5,310 and 19,850 insects per trap. The populations giving the highest captures in the traps showed the lowest bark colonisation density (248 vs. 489 maternal galleries per m2) and the best breeding performance. The populations of parasitoids and predators corresponded t...