Different soybean plant arrangements affect ground beetle assemblages

It was expected that there would be a relationship between plant density and arrangement within soybean plantations and ground beetles due to changes of abiotic habitat conditions. The aim of this study was to determinate the effect of different plant arrangements of soybean plants on the abundance and species diversity of ground beetles (Coleoptera, Carabidae). The studies were conducted from 2015 to 2017 at the Experimental Research Station, Wrocław, Poland. The occurrence of beetles was examined on soybeans, growing in four different treatments: row spacing of 15 cm or 30 cm, and seeding density of 50 or 90 seeds per m2. The experiment was conducted in a split-plot design in four replicates. Ground beetles were collected with 16 pitfall traps, with one trap in the middle part of each plot. The obtained results show that the general number of ground beetles was similar between the treatments. Some minor effects were found in species number, which was higher in the lower row spacing treatment. Only less abundant species were significantly affected. The most abundant species in all years and treatments were Pseudoophonus rufipes, Harpalus affinis, Calathus fuscipes and Pterostichus melanarius. The abundance of the above-listed common ground beetle species did not differ significantly between treatments.