How do different agricultural managements interfere with the Phytoseiidae mite (Acari: Phytoseiidae) community in apple trees?

Abstract

In this study we performed the sampling of phytoseiid mites in different apple production orchards, and we evaluated the richness and abundance of these mites, as well as their distribution in the different strata of the plants. Furthermore, we studied how the different apple tree cultivars affect the diversity and distribution of these predatory mites. Collections were carried out in apple orchards in three different production areas: 1- organic agriculture (Antônio Prado, RS); 2- conventional agriculture (Muitos Capões, RS); 3- regenerative agriculture (São Joaquim, SC). In total, seven orchards were evaluated, in Muitos Capões and São Joaquim, two orchards of the Fuji and Gala, whereas in Antônio Prado, three cultivars (Eva, Fuji and Gala) were considered. In each orchard, 40 plants were evaluated, and from each plant a median branch was randomly chosen from which a leaf was removed from the apical, median and basal thirds. The collected leaves were taken to the laboratory, they were observed and the mites found mounted in Hoyer's medium and identified. A total of 695 phytoseiid specimens were collected. Greater abundance was noted in the apical stratum of plants of the Gala cultivar, demonstrating the effect of cultivar and stratum on phytoseiid richness, abundance and distribution. Neoseiulus californicus (McGregor) (Phytoseiidae) was the main species in areas of conventional and regenerative cultivation, being present in all evaluated orchards, but with low occurrence in areas of organic management. In organic orchards, species of the genus Euseius [Euseius mesembrinus (Dean) and Euseius inouei (Ehara and Moraes)] (Phytoseiidae) were more abundant. The results suggest that producers consider less intensive use of pesticides and herbicides in orchards in order to maintain populations of predatory mites due to their potential for biological control.