A diversidade e o papel da fauna de formigas em áreas agrícolas submetidas ao cultivo orgânico e convencional

Abstract

Agriculture is an essential activity for food supply and for the Brazilian economy, but it is among the practices that cause the most negative environmental impacts. Among the most serious problems caused by agricultural activities is the loss of biodiversity. However, alternative crop types to conventional ones, with the absence of synthetic pesticides and other forms of management of cultivated areas impacting the environment, can minimize the negative effects of agricultural areas on biodiversity. This is the case with organic food crops. Ants (Hymenoptera; Formicidae) are among the most common animals in cultivated areas, and because ant communities are indicative of biodiversity, they can be used as model organisms in studies aimed at evaluating the influence of the characteristics of cultivated areas on biological diversity. The present study had as general objective to investigate the diversity and functions of the myrmecofauna in eight areas cultivated with the conventional system and eight areas of organic cultivation in the city of Paraíba do Sul, RJ. In each area 15 pitfall traps containing 70% alcohol were installed. The work was divided into two chapters. The first chapter aimed to evaluate the richness, diversity, abundance and composition of the ant fauna in areas of organic cultivation and conventional cultivation. In addition, it also aimed to evaluate the factors that influence the myrmecofauna in the cultivated areas. In the second chapter, the objective was to study the functional groups of ants in areas of organic cultivation and conventional cultivation, to investigate the influence of myrmecofauna on the abundance of other insects in agroecosystems and to compare the fauna of arthropods, with emphasis on insects, with conventional and organic cultivation. Also identifying the species of ants beneficial or causing problems in the agroecosystems studied. It was observed that areas with organic food cultivation are more conducive to the maintenance of an ant fauna more diversified than areas under the conventional cultivation system. The abundance of ants was higher in organic than conventional crops. In addition, it was concluded that the characteristics of the cultivated areas influence the richness, diversity and abundance of the myrmecofauna, mainly leaf litter depth, number of cultivated species, air temperature and variations in cultural dealings. The richness of functional groups mean was significantly higher in organic than in conventional crops. It can be affirmed that the functional group of ants that obtained the second greatest richness "Omnivorous that inhabit the soil, the leaf litter and the plants" can play an important role in the biological control of Coleoptera in the areas of conventional cultivation. The high richness of the functional groups of ants "Omnivorous that inhabit the soil and the leaf litter" and "Predators generalists that inhabit the soil and the leaf litter", although they do not present significant relation between the abundance of ants and the abundance of Hemiptera, Orthoptera and Coleoptera, shows a potential for the use of these ants in the biological control of insect pests.