Leaf litter in fruit orchards in winter is a hot spot for invertebrate predators

Abstract

Overwintering of invertebrates in Central Europe drives the population dynamics in the subsequent seasons and have the direct impact on ecosystem services and biodiversity conservation. The objective of this study was to investigate the spatial and temporal distribution of overwintering arthropods in the fallen leaves in three fruit orchards. The autumn and early spring distributions of several arthropod taxa were studied in fallen leaves in apple, pear, and cherry orchards in relation to several environmental variables. In the predefined areas (1 x 1 m) samples of fallen leaves were collected in autumn and spring 2018/2019 and 2019/2020. Data from an area of 168 m2 was used for evaluation. A total of 1281 arthropod individuals were collected. The most abundant were spiders with 787 specimens. Samples also comprised 17 other arthropod species or higher taxonomic categories, 10 of which were considered as beneficial, four as pests, and three were unclassified. Spiders were analysed more precisely due to their dominance and their importance in plant protection as biocontrol agents. We demonstrate for the first time that fallen leaves in fruit orchards offer a suitable overwintering microhabitat for predatory arthropods, which contribute to the biological control of pests, and comprehensively evaluate the overwintering arthropod assemblage in relation to several ecological and environmental variables.