Phytoseiid mite diversity (Acari: Mesostigmata) and assessment of their spatial distribution in French apple orchards

Abstract

The present study reports the results of surveys carried out over two years in 173 apple orchards in France. Eleven species of Phytoseiidae were observed, among them three were dominant: Amblyseius andersoni, Kampimodromus aberrans and Typhlodromus (Typhlodromus) pyri. Cydnodromus californicus was also found but only in some orchards and nearly always in association with one of three dominant species. This observation confirms the faunal modification initiated more than ten years ago. Amblyseius andersoni was recorded in high densities in nearly all the regions considered. Typhlodromus (T.) pyri was also widespread, even if particularly frequent and abundant in the Rhône-Alpes region. Kampi-modromus aberrans was localised in some regions; it was especially frequent and abundant in the Mediterranean region. An identification key containing the eleven reported species is provided. Taylor's law was applied in order to characterize the Phytoseiidae distribution in apple orchards. The distribution is clearly aggregative, whatever the region and the Phytoseiidae species considered. Relationships between the occupation rate and the mean number of Phytoseiidae per leaf was established and an abacus was constructed to facilitate surveys and the counting during practical assessments of Phytoseiidae fauna in apple orchards. © Tixier M.S. et al. Acarologia is under free license.