Improved Funnel-Type Extractors for Soil Arthropods

Berlese and Tullgren funnel-type extractors have now been used for qualitative work for more than 50 years. Many variants have been described since then but little progress has been made towards adapting them for reliable quantitative work. The history of the subject is given in an earlier paper (Macfadyen 1953) in which the inadequacy of current practice was demonstrated (see also Forsslund 1948) by comparing funnel yields with direct counts. It was later shown (Macfadyen 1955) that the control of temperature and humidity both above the soil sample and beneath it in the funnel can result in increased yields. The purpose of the present paper is to consider three methods by which control can be achieved in practice and the effects of such control on the yield of animals. Each of these methods is appropriate to a different set of circumstances as follows: