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San Carlos de Bariloche, Argentina

Paola Perez S.,National University of Comahue | Carlos Corley J.,Instituto Nacional de Tecnologia Agropecuaria | Farji-Brener A.G.,Laboratorio Ecotono
Agricultural and Forest Entomology | Year: 2011

The economic losses associated with crop damage by invasive pests can be minimized by recognizing their potential impact before they spread into new areas or crops. We experimentally evaluated the preferences of the leaf-cutting ant Acromyrmex lobicornis (Hymenoptera: Formicidae) for the most common conifer species commercially planted in northern Patagonia, Argentina. The areas of potential forest interest in this region and the geographical range of this ant overlap. We performed field preference tests and monitored the level of ant herbivory on planted conifer seedlings next to nests. Acromyrmex lobicornis preferred some conifer species and avoided foraging on others. Pseudotsuga menziesii and Austrocedrus chilensis were the less preferred species, Pinus ponderosa and Pinus contorta were the most preferred by A. lobicornis. The item mostly selected by ants was young needles from P. contorta. This species was also the pine mostly defoliated. Seedlings without ant-exclusion showed a mean±SE of 60±5% defoliation during the sampling period. Pinus ponderosa was less defoliated; control seedlings showed a mean±SE of 8.5±1% of leaf damage in the sampling period. The present study shows how the use of simple field tests of leaf-cutting ant preferences could allow an improved selection of appropriate conifer species for future plantations in areas where leaf-cutting ants are present. © 2010 The Authors. Agricultural and Forest Entomology © 2010 The Royal Entomological Society.

Elizalde L.,Laboratorio Ecotono | Elizalde L.,National University of Quilmes | Fernandez M.A.,National University of Quilmes | Guillade A.C.,National University of Quilmes | Folgarait P.J.,National University of Quilmes
Journal of Pest Science | Year: 2015

The damage to plantations by pests is often determined by perceptions rather than objective data, resulting in excessive use of pesticides. Leafcutter ants are considered important pests to plantations in America. We evaluated the difference in Pinus taeda biomass consumption by four Acromyrmex leafcutter ant species which co-inhabit plantations of this pine species. These ants exhibit morphological and behavioral differences, i.e., Ac. heyeri has mandibles adapted to cut monocots, while the other species cut dicots, which may result in differences in their consumption of pine. We collected the plant biomass that ants carried into their nests and recorded the foraging activity in different seasons throughout a year. The P. taeda biomass carried into leafcutter nests was less than 20 % compared to total plant biomass. Colonies with greater foraging activity carried a greater amount of total biomass, but they did not carry more pine biomass. The leafcutter ant species studied differed in their use of pine biomass, but not of total biomass. Acromyrmex ambiguus and Ac. crassispinus were the species carrying the greatest amount of pine biomass and with more colonies using pine, whereas very little amounts of pine were carried by Ac. heyeri and by very few colonies. Thus, leafcutter ant species do not cause the same damage to pine plantations. Our results also highlight the importance of pest management strategies based on a thorough knowledge of the biology of the species, including those characteristics which can predict the use that each species will make of the plantation. © 2015 Springer-Verlag Berlin Heidelberg

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