Host species for the southern pine beetle include loblolly pine and Virginia pine, which commonly co-occur within forests of the southeastern United States. A study within one mixes species site (ca. 3 ha area) in the Bankhead National Forest of Alabama indicated that southern pine beetles tended to preferentially attack Virginia pine even though they had markedly higher reproductive success in loblolly pine. If this pattern is general, then beetle infestations should tend to favor the persistence of loblolly pine relative to Virginia pine in sites where they co-occur at the spatial scale that beetle individuals discriminate among host trees (< 1 ha). However, if beetles have lower reproductive success within Virginia pine, then infestations should be less likely to persist and grow within pine stands that are chiefly Virginia pine, in which case stands of Virginia pine should be more likely to survive an epidemic of outbreaks than stands of loblolly pine. These predictions were supported by sampling of pine survival patterns across a 2500 km2 landscape that experienced a 3-year epidemic of southern pine beetles. Thus, southern pine beetles tend to reduce the abundance of Virginia pine relative to loblolly pine at one spatial scale but increase it at a coarser spatial scale. Furthermore, southern pine beetles tend to reduce the alpha diversity of pine stands and create a landscape that contains fewer mixed stands. Results have implications for reforestation strategies because Virginia pine can apparently function similar to a "trap crop" and increase the survival probabilities of other pine species wtihin the same infested forest.
Species 1: Coleoptera Scolytidae Dendroctonus frontalis (southern pine beetle)
Keywords: host susceptibility, spatial scale
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