Effects of groundcover management on ground beetles (Coleoptera: Carabidae) in an apple orchard

Abstract

A field experiment was conducted in a cider-apple orchard to evaluate the effect of six groundcover management systems (pine-bark, plastic and straw mulches, tillage, herbicide and natural soil) on the occurrence of ground beetles (Coleoptera: Carabidae). Eight species of carabids were collected in pitfall traps. The three most common beetles, Steropus gallega Fairmaire (65.8%), Pseudophonus rufipes (DeGeer) (18.2%) and Poecilus cupreus L. (14.6%), represented more than 98% of the total catches. The specific dominance depended on the sampling date. The soil management treatment significantly affected the following parameters. (1) The overall carabid catch: the plastic mulch (5.6% of the total catches) negatively affected total carabid collection, which was higher in the tilled (24.3%) and herbicide-treated (21.4%) plots, although not significantly different from the natural soil (16.5%), straw mulch (16.3%) and pine-bark mulch (15.9%) treatments. (2) The specific preferences of the three most common carabids: the plastic cover adversely affected the catches of S. gallega whilst P. rufipes was collected in greater numbers in tilled areas and P. cupreus in the herbicide treatments. (3) The structure of the carabid community: based on species richness, diversity and evenness indices, herbicide and tillage provided the most diverse carabid community and the straw mulch the poorest. It was concluded that groundcover management in apple orchards may affect the activity density of epigeic predators which may contribute to the natural control of pests.