The bark beetle Ips pini (Say) (Coleoptera: Scolytidae) is a chronic pest of pine forests throughout North America. Male beetles bore into the subcortical tissue of trees and emit aggregation pheromones, attracting male and female conspecifics. Various predators exploit these pheromones as kairomones. The complement of natural enemies arriving at the tree changes as pheromone production ceases and bark beetle broods develop. We conducted a field experiment in which we monitored the arrival and reproduction of natural enemies of I. pini in red, jack, and white pine logs. The predators Thanasimus dubius (F.) (Coleoptera: Cleridae) and Medetera spp. (Diptera: Dolichopodidae) arrived simultaneously with colonizing I. pini, while Roptrocerus xylophagorum (Ratzeburg) (Hymenoptera: Pteromalidae) arrived at later stages of brood development. Dipteran predators were primarily reared from red pine logs, while pteromalid parasitoids and cerembycids were primarily reared from white pine. Overall attraction and reproduction of I. pini did not differ between pine species. These data suggest that separation of natural enemies across time and host trees may reduce interspecific competition.
Species 1: Coleoptera Scolytidae Ips pini (pine engraver)
Species 2: Hymenoptera Pteromalidae Roptrocerus xylophagorum
Species 3: Diptera Dolichopodidae Medetera spp
Keywords: natural enemies, competition
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