Fragmentos florestais no entorno de cafezais e sua influência no controle biológico conservativo

Abstract

Coffee has enormous historical, social, and economic importance in Brazil and Minas Gerais, especially since the 19th century. However, coffee plants are attacked by various pests that cause significant damage and lead to a high use of pesticides, which burden the growers and generate considerable environmental liabilities. Among these liabilities is the death of natural enemies, creating a problematic vicious cycle. One solution to this problem is the use of conservative biological control, a technique that aims to attract and maintain beneficial insects, the natural enemies, in the cultivation areas through vegetation management within or around the crop to control the pest insects. Although promising, technical aspects of conservative control, such as the species to be used for enrichment or the spatial dimensions of the necessary border areas for efficient control, are still poorly understood. In this study conducted on Cachoeira and Goiaba farms in the municipality of Santo Antônio do Amparo, MG, the influence of forest fragments and fallow areas on the richness and abundance of parasitic insects in coffee pests was evaluated in order to observe the influence of fragment size on the richness, abundance, and diversity of these populations. For this purpose, 100 traps were placed in the field, installed in conventional coffee plots at Cachoeira Farm and organic coffee plots at Goiaba Farm. Additionally, traps were also set up in points within the forest close to the plots. Then, an imaginary circle with a diameter of 200 meters was drawn from each point, and based on satellite images, the forest/coffee ratio was established and the diversity of parasitic insects for each of these ratios was analyzed, both in organic and conventional management. Laboratory identifications and non-metric scaling (NMDS), dissimilarity (SIMPER), and generalized linear model (GLM) analyses were conducted. The results of NMDS and SIMPER showed significant differences among all treatments from both farms. The GLM indicated that there was a difference in richness between treatments with 10% and 60% surrounding forest at Cachoeira Farm, with no significant difference in abundance and diversity. At Goiaba Farm, there were differences in abundance and richness between the forest treatments with 20% and 40% on one side, and 50%, 60%, and 70% on the other side. It can be concluded that different proportions of surrounding forest influenced the assembly of parasitic insects, especially in conventional management, but there was no linear increase in diversity with an increase in the proportion of surrounding forest. More comprehensive studies over time and space, as well as identifications at the genus or species level, would provide more conclusive results.