Potential damage byAcromyrmexant species in pine plantations in southern Brazil

摘要

Acromyrmexspecies primarily attackPinus taedaplantations during the first months after planting, with more intense damage in the first 30 days. We evaluated potential damage byAcromyrmex crassispinusandAcromyrmex subterraneusin 30-day-oldP. taedaplantations in southern Brazil by assessing the number of attacked plants and the distance reached by each colony, along with the losses in plant development resulting from different levels of defoliation. Both species were significant pests in newly established pine plantations. A single colony can attack a substantial number of seedlings (up to 453 seedlings). Colonies with larger nests attacked more plants and ranged farther;A. crassispinusreached 59 m andA. subterraneus87 m. After 10 years, no significant losses in plant development were seen in seedlings defoliated less than 50% at 30 days after planting. But when defoliation of the young plants attained 75%, 100%, and 100%, including the cut of the apical meristem, volume losses reached 32%, 37%, and 43%, respectively. Leaf-cutting ant controls should be carried out in plantations ofP. taedawithin 30 days of planting to avoid attacks. When seedlings are defoliated more than 75%, they should be replanted to avoid future losses in final wood volume.