Parasitoids of the Southern Pine BeetleThis article is part of a larger document. View the larger document here.
Hymenopterous parasitoids make up a significant portion of the natural enemy complex associated with the southern pine beetle (SPB). Collectively, parasitoids can affect the growth of individual SPB infestations and area populations by reducing the survival rates of developing SPB larval/pupal broods. A substantial body of information on parasitoids has been accumulated, mostly during and after research supported by the Expanded Southern Pine Beetle Research and Applications Program (ESPBRAP) during the 1970s. The parasitoids most closely associated with the SPB have been identified, and a key to larvae of the most abundant species is available. The sequence of arrival of parasitoids at infested pines relative to SPB attack and brood development has been documented. Some chemical cues by which parasitoids locate trees infested with SPB broods that are in susceptible developmental stages have been determined. However, the precise mechanism by which parasitoids locate specific hosts beneath the bark has not been described, although it is thought to involve specific olfactory cues. Factors that affect parasitoid efficacy such as host density and bark thickness have been quantified, and the overall contribution of parasitoids to natural enemy impact has been estimated and incorporated into population growth models.