Biologia e parasitismo social em Acromyrmex subterraneus subterraneus Forel, 1893 e Acromyrmex ameliae Souza et al, 2007

• Autor(a) principal: Soares, Ilka Maria Fernandes
• Data de Publicação: 2007
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/945
• topic: Formigas; Parasitismo social; Acromyrmex; Formiga cortadeira; Ants; Acromyrmex; Social parasitism; Leaf-cut ants; CNPQ::CIENCIAS BIOLOGICAS::ZOOLOGIA::ZOOLOGIA APLICADA

Social parasitism is the coexistence in the same nest of two species of social insects, one of which is parasitically dependent on the other. There are several types of social parasitism, the inquilinism being the most derived. In this relationship, the parasitic species depend entirely on the host. Workers may be present but usually in small numbers, and do not perform all the tasks necessary for colony maintenance. Acromyrmex ameliae, a social parasite of Acromyrmex subterraneus subterraneus, and of Acromyrmex subterraneus brunneus, was discovered in 2003 in eucalypt plantations located in the Itapoã (V&M Florestal Ltda.) Farm, in Paraopeba, MG. Further studies of this parasite are described in this work, dealing with biological and behavioral aspects of the association host-inquiline and its evolution. Acromyrmex ameliae is an inquiline that has minor workers, differing from the host workers by having a rugous, hairy body, prominent eyes and a bulla-spiracle distance that is larger than that of the host workers. Having also smaller metapleural glands, it is possible that they are more susceptible to pathogens than host workers. The parasite queens are smaller than the host workers and their presence, as well as of their workers, do not interfere significantly in the egg production but inhibit the production of sexuals of the host subspecies. Spermatozoa are different in both species. Acromyrmex subterraneus subterraneus has spermatozoa and spermatic nuclei longer (105 µm and 9.5 µm respectively) than A. ameliae (91.3 µm and 7 µm, respectively). Spermatozoa diameter of the host is constant, except a its end, when it tapers abruptly. In the parasite, the nuclei thins abruptly from the anterior third. Both host and parasite workers tend to the immatures of both species although the host workers do prefer co-specific immature nestmates. Larvae from the same nest are not discriminated. Host workers are attracted by larvae of their species, if they are not from the same nest. However, if larvae are from the same colony, there is no preference. The entrance and permanence of a parasite queen in a host nest are related to its fecundity and to the lapse of time since colony invasion. The secretions of the Dufour gland seem to be associated to the invasion and acceptance process, because secretions from virgin females do not have an attractive effect of workers but those of fertilized queens are attractive to workers of both species. These secretions must be important for maintenance of parasitism; those of the parasite attract both species while those of the host queen attract only host workers. Host queens taken from non-parasitized colonies are more aggressive toward queens of A. ameliae than to queens from parasitized nests. Host queens showed larger quantities of cuticular hydrocarbons than parasite queens; however, opposite results were found for workers and larvae. This deserves further investigation.