Sampling soil earthworm populations using household detergent and mustard

Abstract

Abstract Sampling earthworm populations in soil using detergent or mustard is compared with traditional hand-sorting techniques. The physiological effects of these vermifuges on earthworms are reported Earthworm populations are a valuable educational resource for ecological and environmental studies. However, sampling them is more difficult than for other invertebrate species. Standard practice has been to use a chemical irritant to bring earthworms to the surface, but the use of the most effective chemical, methanal (formalin), is restricted by COSHH regulations. Four litres of household detergent applied to the soil in a 50 by 50 cm quadrat at a concentration of 20 ml I-1 makes a cheap, simple to handle, and efficient vermifuge. However, earthworms are adversely affected by the detergent and are likely to die after extraction. Mustard solution applied at 25 ml I-1 is as effective as detergent and is less toxic to earthworms but is more expensive and difficult to apply. Both techniques are far less efficient than hand sorting the soil but this is a slow and laborious procedure. Detergent and mustard vermifuges can only be recommended for comparative studies of earthworm populations. Keywords: EarthwormsSampling techniquesVermifuges