Responses of the earthworm Lumbricus terrestris (L.) to iron phosphate and metaldehyde slug pellet formulations A. Mark Langan * , Emma M. Shaw Department of Environmental and Geographical Sciences, John Dalton Extension, Manchester Metropolitan University, Chester Street, Manchester, M1 5GD, United Kingdom Received 9 January 2005; received in revised form 30 January 2006; accepted 13 February 2006 Abstract Earthworms are susceptible to many pesticides, including some slug pellet formulations, but very little is known about the effects of iron phosphate formulations on non-target fauna. In artificial burrows, the study provides the first evidence of deleterious impacts on the survival and behaviour of the earthworm Lumbricus terrestris of pelleted iron phosphate. This occurred at eight times recommended field application rates, but it is noteworthy that this type of trial requires higher numbers of pellets to be applied as animals usually contact only very few pellets. Effects were stronger than another widely applied pelleted formulation (metaldehyde) which did not differ significantly from control groups, even when this treatment was applied at very high rates (35 times recommended field application rates). Again few pellets were contacted by the earthworms, but more than in iron phosphate assays. Exposure to iron phosphate increased earthworm mortality, and surviving individuals gained less mass than those exposed to metaldehyde (significantly less than the control group; metaldehyde did not differ significantly from the other two treatments). Significant reductions in the rates at which pellets and leaves were removed from the soil surface were observed after exposure to iron phosphate, indicating reduced surface foraging activity. Findings are discussed in relation to the chemical formulations and other pellet characteristics and highlight the requirement for dose-dependent earthworm assays with iron phosphate formulations. # 2006 Elsevier B.V. All rights reserved. Keywords: Molluscicides; Soil function; Foraging behaviour; Artificial burrows; Daniel funnels 1. Introduction Earthworms are of paramount importance in many soil systems, often comprising the dominant fraction of the soil macrofauna. The structure and size of earthworm communities varies greatly between habi- tats, for example, Lumbricidae may attain abundances of over 2000 m À2 in pastures (Lee, 1985). Earthworm densities are lower in crops, reflecting the impacts of cropping and management practices (Jordan et al., 2004). Often, their activities have positive influences on soil functioning, for example recycling nutrients and promoting plant root growth (Devliegher and Ver- straete, 1997; Scheu, 2003) and other aspects of the ecology of plant communities (Kreuzer et al., 2004). The addition of fertilisers tends to enhance earthworm populations (Edwards and Bohlen, 1996), however, negative impacts of biocides (particularly insecticides) on earthworms are well documented (Greig-Smith et al., 1992; Spurgeon et al., 2003; Scheu, 2003). Molluscicidal impacts on earthworm health under laboratory conditions suggest a potential to reduce soil ecosystem function. Relatively high sensitivity to carbamates has been reported (Edwards and Bohlen, 1996) and laboratory exposure to methiocarb pellets www.elsevier.com/locate/apsoil Applied Soil Ecology 34 (2006) 184–189 * Corresponding author. Tel.: +441612471583; fax: +441612476316. E-mail address: m.langan@mmu.ac.uk (A.M. Langan). 0929-1393/$ – see front matter # 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.apsoil.2006.02.003