Mite fauna abundance and composition on apples in southern Brazil

Abstract

The production of apples (Malus domestica: Rosaceae) in Brazil is concentrated in three states in the southern region of the country. This crop is of great economic importance for the region, and is usually susceptible to infestations of mite populations. However, recent surveys of mite species associated to apples are scarce. The aim of the present study was to fill this void by analyzing species abundance and composition on three apple cultivars in the southern region of Brazil. The survey was carried out in the states of Rio Grande do Sul (RS), Santa Catarina (SC), and Paraná (PR). A total of 94 apple orchards were evaluated (43 Gala, 40 Fuji and 11 Eva), in 19 municipalities. Twenty plants were sampled from each orchard in March 2019, with four leaves collected from each plant, thus totaling 80 leaves/orchard. Mites were screened and identified in the Laboratório de Acarologia of Universidade do Vale do Taquari - UNIVATES. Data were analyzed using the R software with mixed generalized linear models, non-metric multidimensional scaling, and PERMANOVA. A total of 4,909 mite specimens were identified, belonging to eight species and six genera, of which 1,833 were classified as phytophagous, 1,758 as predators, and 1,318 as generalists. The most abundant phytophagous species was Aculus schlechtendali (33.55%), followed by the predator Neoseiulus californicus (33.14%) and by the generalist Tarsonemus (Tarsonemus) sp. (23.99%). Abundance was similar between Eva and Fuji cultivars. However, these cultivars differed in composition, as did Eva and Gala. The mean number of mites found in Santa Catarina and Rio Grande do Sul was similar, although Paraná had a higher number. Species composition also differed among the three states evaluated. Considering the importance of the apple production in the southern region of Brazil, studies on species composition and abundance are important, aiming to monitor potential damage-causing organisms to the crop and associated predators.