The effect of pitfall trap construction and preservative on catch size, species richness and species composition of ground beetles (Coleoptera: Carabidae)

Michal Knapp,Jan Růžička

doi:10.14411/eje.2012.054

Abstract

Pitfall trapping is the most frequently used sampling technique for epigeal arthropods. Trap design could significantly affect the catch so the results of studies using different trap designs may be difficult to compare. Although species composition is frequently investigated in ecological studies, however when pitfall trapping is employed, the effect of trap design on the recorded species composition is rarely considered. In the present study, we investigated the effect of trap construction (funnel or cup trap) and the preservative used (formaldehyde or propylene glycol) on total catch, catch of particular species, species richness and species composition of the ground beetle assemblage sampled. We were interested in the extent to which trap design could bias these charac- teristics. Total catch was significantly affected by trap construction and preservative used, with the effect of the latter being the stronger. Species richness was only slightly affected by trap design when assemblages caught by traps of a particular type were cor- rected for unequal sample size. Moreover, we show that the traps of different designs differ in their efficiency for catching particular species of carabid and thus the composition of assemblages recorded using pitfall traps is affected by trap construction and the pre- servative used. We conclude that to assess the full significance of the effect of pitfall trap design on the results of ecological studies on epigeal arthropods it is necessary to simultaneously use traps of various designs.

Highlights

Proper methodology is the basic prerequisite for obtaining reliable results in scientific studies (Elphick, 2008)
Carabus nemoralis and Bembidion lampros were caught in higher numbers by the funnel traps, and more Brachinus crepitans, Harpalus latus, Harpalus rubripes, Notiophilus palustris and Pterostichus ovoideus were caught by the cup traps
The preservative used significantly affected the size of the catches of six species (Carabus granulatus, Carabus nemoralis, Harpalus rubripes, Ophonus azureus, Poecilus versicolor and Pterostichus ovoideus), while, for all the significantly affected species, except Ophonus azureus, traps filled with propylene glycol caught more of these beetles than those filled with formaldehyde

Summary

Introduction

Proper methodology is the basic prerequisite for obtaining reliable results in scientific studies (Elphick, 2008). There are a number of ways of sampling epigeal arthropods (e.g., ground beetles), but pitfall trapping is by far the most widely used. This sampling technique was used in almost 90% of the field studies on the ecology of ground beetles published in 2008–2010 and cited on the Web of Science. The use of pitfall traps to sample epigeal arthropods has been criticised continuously since the 1960s (Greenslade, 1964; Adis 1979; Topping & Sunderland, 1992; Southwood, 1994; Spence & Niemelä, 1994; Hatten et al, 2007)

Methods

Results

Conclusion