Area-wide efficacy of a localized forest pest management practice

Few experimental studies have examined the movement of forest pest populati ons, particularly in response to management tactics that disrupt the growth of pest infestations. We quantified the interinfestation patterns of dispe rsal of the southern pine beetle, Dendroctonus frontalis Zimmermann (Coleop tera: Scolytidae), by monitoring the fates of fluorescently marked beetles after emergence from small natural infestations. Dispersal patterns from 3 untreated infestations were compared with those from 6 infestations treated with the widely used disruption suppression tactic, cut-and-leave (infeste d trees are felled and left in the forest). Among untreated infestations, 1 0 +/- 4% (+/-1 SE) of the marked beetles were successful in colonizing expe rimentally created infestations located 100-500 m away. The highest proport ion of marked beetles was recaptured at the nearest experimental infestatio ns (at 100 m) and recaptures declined precipitously with distance from the source. Dispersal by beetles emerging from disrupted infestations showed a similar pattern to untreated infestations with respect to distance, but a m uch greater fr action of the beetles were recaptured at each distance. Over all, colonization success for treated infestations was 37 +/- 6%, almost a 4-fold increase over untreated infestations. This suggests that by altering the dispersal patterns of beetles, the cut-and-leave suppression tactic ma p favor increased densities of flying beetles, and possibly more infested t imber, in the surrounding region. Effective control of mobile pests may be enhanced by expanding our spatial scope and seeking to maximize the area-wi de, not just the local, efficacy of management tactics.