S. Mahunka szerk.: Folia Entomologica Hungarica 56. (Budapest, 1995)

Design and use of a hand-hold suction sampler, and its comparison with sweep net and pitfall trap sampling F. Samu and M. Sárospataki Design and use of a hand-hold suction sampler, and its comparison with sweep net and pitfall trap sampling - The paper describes a simple design of a hand-hold suction sampler which was modified from a commercially available garden leaf blower. It also reports on a preliminary study where the range of arthropod taxa collected by the suction sampler, pitfall traps and by sweep netting, carried out in an alfalfa field and a neighbouring meadow was investigated. The three collecting methods produced significantly different pictures of the arthropod communities. The principal component analysis showed that there was much overlap between catches by suction and sweep net sampling, whereas pitfall trap catches were markedly different in the composition of the various taxa caught. INTRODUCTION In entomological research it has always been in the centre of interest to what extent samples gained by various collecting methods represent the true abundance structure of insect communities. Southwood (1966) classified collecting methods as relative and absolute population estimating methods. From relative methods it is difficult to derive valid abundance estimates of populations. However, these methods are widely used because they require simple equipment, they are logistically feasible, even if unattended they collect continuously over longer periods of time. Pitfall trapping can be considered as a typical representative of these methods. Pitfalls are frequently used in ecological studies, often as the only method. Catches of pitfalls are sometimes referred to as activity abundance', although recent criticism showed that not only abundance and variable intensity of activity, but also species specific 'trappability' determine the relative catches of different species (Sunderland et al. 1995). Thus translating pitfall trap catches into relative abundance data requires careful calibration and specific knowledge about the biology of each species involved (Samu & Sárospataki 1995). Absolute density estimating methods are usually based on sampling from units of a habitat (Southwood 1966). Suction sampling devices, which collect arthropods from their natural habitat by the power of air flow, can make absolute sampling relatively easy; therefore they might represent viable alternatives to relative methods. The first suction devices were constructed in the 1950's. Johnson et al. (1957) modified a portable electric blower for this purpose, Southwood and Pleasance (1962) devised a hand-operated suction apparatus. In Hungary Győrffy (1980) reported the construction of a suction sampler which was built from a motorised sprayer. These equipments had a small opening of 2-A