Resposta comportamental de formigas cortadeiras ao sesquiterpeno [beta]-eudesmol

• Autor(a) principal: Marinho, Cidália Gabriela Santos
• Data de Publicação: 2006
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/854
• topic: Formigas cortadeiras; Comportamento; Comunicação química; Eucalyptus maculata; Sesquiterpenos; Leaf-cutting ants; Behavior; Chemical communication; Eucalyptus maculata; Sesquiterpene; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::ENTOMOLOGIA AGRICOLA

A previous research with the sesquiterpene [beta]-eudesmol extracted from leaves of Eucalyptus maculata nest and offered to ants at their foraging arenas at the nest showed that it induced behavioral modifications among nestmates of Atta sexdens rubropilosa. These alterations were characterized by inspection and bites at different body parts of a contaminated ant, with mutilation and even death. Based on these findings, this research aimed at evaluating the effect of the synthetic commercial [beta]-eudesmol on colonies of leaf-cutting ants. The studies were conducted in laboratory colonies at the Insectary of the Animal Biology Department of the Federal University of Viçosa (UFV). Room conditions were: 25±5oC, 75±10%R.H. and 12:12 (L:D). Small (1.5L of fungus garden) and large colonies (25.0L of fungus garden) of Atta sexdens rubropilosa, of A. laevigata and of A. bisphaerica; colonies of Acromyrmex subterraneus subterraneus and Ac. subterraneus molestans (fungus volume between 5.0 and 6.0L) and colonies of Solenopsis invicta were used to conduct the bioassays. They consisted of simultaneously offering, at the foraging arenas, filter paper fragments impregnated with either [beta]-eudesmol (treatment), with the solvent used in the product dilutions (control) or only the filterpaper fragment (blank). [beta]-eudesmol induced aggression among nestmates, the reaction being stronger in larger colonies and characterized by inspection, biting of legs, abdomen and head, followed by mutilation and death. In a second step, it was verified that the substance promoted aggression only in colonies of Atta, with strongest effects on A. sexdens rubropilosa. [beta]-eudesmol did not elicit reactions when its application was topic on the workers. On the last part of the research, the mode of action of [beta]-eudesmol was investigated. Bioassays were conducted in ants able or unable to release alarm pheromone and in contact with the product. These bioassays were based on the hypothesis that the product synergizes the alarm pheromone. Furthermore, chemical analyses were performed on the cuticle of workers that had previous contact with [beta]-eudesmol. The hypothesis was that a possible chemical modification of the cuticle resulted on interference with the individual odor and, therefore, on nestmate recognition. The results revealed that [beta]- eudesmol interferes with both the alarm system and the recognition system of nestmates. They suggested that the product ruptures the colony cohesion through a modification of the cuticle and interference on the alarm system.