Slugs as pests

Abstract

Few species of slug appear to have been adversely affected by human activities, apart from the localized effects of habitat destruction, while several species have extended their geographical distribution. Several have become considerably more abundant as the result of agricultural and horticultural activities (see Sections 1.2 and 10.5). Arable farming has tended to reduce species diversity and few slug species are found on cultivated land, although several, including D. reticulatum, A. hortensis and T. budapestensis have successfully adapted to these conditions and have become established in many areas as pests of field and horticultural crops (Section 10.3.3). Slugs may also hinder the regeneration of deciduous woodlands and Elliott (1985) showed that A. ater and A. hortensis damaged first-season tree seedlings while Urquart (1952) also reported slugs eating tree seedlings. In addition to their importance as crop pests, slugs have been shown to act as vectors of helminth parasites of domestic and wild mammals and birds, including the nematodes, A. cantonensis, which can also cause eosinophilic meningo-encephalitis in man, and A. costaricensis, which causes human abdominal angiostrongyliasis. The economic loss due to abdominal angiostrongyliasis in Central America was estimated by Andrews (1989) to be US$ 5 million per year. The role of slugs as vectors of disease has been discussed in Section 9.2.