Predators of bark beetles and alien species: A story of coevolution and odors

The great European spruce bark beetle (Dendroctonus micans, Curculionidae: Scolytinae) and the boreal spruce beetle (D. punctatus) are two phylogenetically and ecologically close bark beetles. They bore galleries into the bark of spruce in Europe and Asia (D. micans) and North America (D. punctatus). We analyze the mechanisms of coevolution between these species and their specific predators: D. micans-Rhizophagus grandis (Coleoptera: Monotomidae) and D. punctatus-Hapalaraea longula (Coleoptera: Staphylinidae). David Pimentel(2) suggested that a prey could evolve resistance against a longstanding associated predator. To test this hypothesis we compare the reproductive success of each predator on both prey and on the red turpentine beetle (D. valens) which is an ecologically close bark beetle outside the geographical range of the predators. R. grandis females fit their oviposition to prey availability probably relying on kairomones. It is likely (but not established) that H. longula developed a similar process. I proceed to chemical analyses (GC-MS using headspace extraction) to identify oviposition stimuli and inhibitors of each predator. Possible differences between prey may be linked to coevolution with the predator. Bioassays will be able to confirm the role of these molecules. Microorganisms could influence the survival and success of bark beetles, and perhaps also the chemical cues involved in oviposition of the predators. To emphasize their role I consider characterizing the microflora of each bark beetle and using antibiotics. D. micans adults have a reproductive diapause which has never been removed in laboratory. To get full life cycle rearing we use thermoperiods in conditioned rooms to simulate winter. (2)-Hokkanen H. & Pimentel D. (1984) New approach for selecting biological control agents. The Canadian Entomologist, 116: 1109-1121