<span style="font-family: Times New Roman;">Occurrence of the quarantine mite pest Aculus schlechtendali (Acari: Eriophyidae) in apple orchards of Serra Gaúcha, Rio Grande do Sul state, Brazil</span>

Abstract

The aim of this work is to report the presence of Aculus schlechtendali (Nalepa, 1890) (Prostigmata: Eriophyidae) (Apple rust mite—ARM), in apple orchards of Serra Gaúcha, state of Rio Grande do Sul, Brazil. Surveys were conducted from apple leaves of Gala cultivar in a commercial orchard of Vacaria County (S 28' 34.540 W 050' 52.153) in the Northeast region of the state of Rio Grande do Sul, between November 2016 and January of 2017. The morphological traits and the relative measurements matched with those of A. schlechtendali. This is the first report of this mite pest in Brazil, so far regulated as a quarantine pest, and the third country report in South America. Consideration on the potential pest status of ARM is discussed.

Biodiversity and mite population fluctuation in different apple orchards in southern Brazil

“…The fact that A. schlechtendali was the main phytophagous mite collected and present in all orchards evaluated, which serves as a warning to researchers and producers, since it is a species of Brazilian quarantine importance (Ferla et al 2018;Nascimento et al 2020) and already has high populations in different cultivars and producing regions of the country (Silva et al 2022). It was considered an important pest in several countries (Duso et al 2010), especially in nurseries and orchards, where it can be found feeding on flowers, fruits and leaves, affecting the physiological activity of plants, the quality and aesthetics of plants (Easterbrook & Palmer 1996;Walde et al 1997;Spieser et al 1998;Duso et al 2010).…”

“…It was considered an important pest in several countries (Duso et al 2010), especially in nurseries and orchards, where it can be found feeding on flowers, fruits and leaves, affecting the physiological activity of plants, the quality and aesthetics of plants (Easterbrook & Palmer 1996;Walde et al 1997;Spieser et al 1998;Duso et al 2010). To date, in Brazil, A. schlechtendali was not observed causing significant economic damage in apple orchards in the south of the country (Ferla et al 2018;Nascimento et al 2020;Silva et al 2022). It is possible that the species is not causing significant damage to the crop in organic orchards due to the natural control carried out by natural enemies present (Maula & Khan 2015;Solomon et al 2000).…”

Abundance and distribution of Aculus schlechtendali on apple orchards in Southern of Brazil

“…The first report of ARM in Brazil occurred in only one isolated point in the state of Rio Grande do Sul (Ferla et al 2018) and the situation of orchards located in the states of SC and PR was unknown. Our results indicate the presence of ARM in all the producing regions of Southern Brazil, although not in all orchards.…”

“…The introduction of this mite in Brazil may have occurred across borders, or due to the intense crossing of fruits from Argentina and Chile to Brazil. However, the possibility of this species being associated with traffic of vegetal material can't be excluded, despite the controls established in the Brazilian import system (Ferla et al 2018). Besides that, long distance dispersal through air is an important survival strategy to many organisms, allowing them to swiftly colonize new territories or migrate between habitats (Gage et al 1999).…”

“…They can also survive in adverse conditions during the dispersion, like solar radiation, high water transpiration, low temperatures/concentrations of oxygen and the absence of food (Valenzano et al 2019). Two species of phytophagous mites, previously considered quarantine pests, were recently introduced in Brazil: Raoiella indica Hirst (Tenuipalpidae, Red Palm Mite -RPM) (Navia et al 2010) and Aculus schlechtendali (Nalepa) (Eriophyidae, Apple Rust Mite -ARM) (Ferla et al 2018).…”