ARTICLE IN PRESS Crop Protection 22 (2003) 1033–1038 Barriers, repellents and antifeedants for slug and snail control I. Schuder. a,*, G. Porta, J. Bennisonb a University of Newcastle upon Tyne, School of Biology, Ridley Building, Newcastle upon Tyne, NE1 7RU, UK b ADAS Boxworth, Cambridge, CB3 8NN, UK Received 31 March 2003; received in revised form 30 April 2003; accepted 15 May 2003 Abstract Laboratory bioassays were carried out to evaluate the efficacy of various products with potential for slug and snail control in horticulture and agriculture. The products tested were cinnamamide, copper ammonium carbonate, garlic, aluminium and copper foil, a mulch, ureaformaldehyde and the proprietary products SnailBans and Tex-Rs matting. The trials were carried out using the slug Deroceras panormitanum (Lessona and Pollonera, 1882) (D. caruanae) and the snail Oxyloma pfeifferi (Rossmassler,. 1835), which are the most abundant slug and snail pest species found damaging hardy ornamental plants in commercial nurseries in the UK. The tested products had irritant, antifeedant, physical barrier, chemical repellent, or molluscicidal effects or showed a combination of more than one effect. Garlic, ureaformaldehyde and cinnamamide were the three best products for controlling molluscs. In 7 day bioassay trials these products had mortality rates between 20% and 95% which was significantly higher than on the untreated compost. In comparison to the untreated compost they also gave significant reductions in damage, between 41% and 100%, depending on species and application technique. Further investigations are needed to evaluate their efficacy under field conditions, the behavioural response of the slugs and snails, the most cost-effective concentrations and the best application techniques, and to understand the mode of action of the products. Some of the products will only be applicable in horticulture due to their cost or the practicalities of their use. However, most of the products also may have potential for use in agriculture as the slug tested, D. panormitanum, is closely related to D. reticulatum, the main slug pest species in agriculture. r 2003 Elsevier Ltd. All rights reserved. Keywords: Deroceras panormitanum; Oxyloma pfeifferi; Pest control; Horticulture; Molluscicide 1. Introduction used in an integrated control strategy, would reduce plant losses, improve plant quality and offer a sustain- Slugs and snails are common pests in UK horticulture able strategy for controlling slug and snail pests with and agriculture. Growers and farmers often experience reduced molluscicide input. The development of alter- difficulty controlling these pests with conventional bait native snail and slug control methods compatible with pellets containing molluscicides such as methiocarb and Integrated Pest Management (IPM) strategies used metaldehyde. For example, in wet conditions the to control other pests will help satisfy increasing efficacy of these pellets can be very low (Hata et al., market demands for ornamental plants and edible crops 1997) leading to unsatisfactory control levels. Further- grown with environmentally responsible production more, poison baits can be toxic to other non-target soil methods. invertebrates, as well as birds and mammals such as Investigations carried out by ADAS in 2000 (unpub- shrews and field mice (Martin, 1993; Purvis, 1996). lished) established two mollusc species as the main pests The development of effective alternatives to conven- in horticultural nurseries producing hardy ornamental tional molluscicides, particularly those which could be plants in the UK: the snail Oxyloma pfeifferi and the slug Deroceras panormitanum. As part of a programme *Corresponding author. Tel.: +44-191-222-5952; of research to establish IPM strategies for these pests a fax: +44-191-222-5229. range of potential barriers, repellents and antifeedants E-mail address: [email protected] (I. Schuder).. were studied and the results are reported here. 0261-2194/03/$ - see front matter r 2003 Elsevier Ltd. All rights reserved. doi:10.1016/S0261-2194(03)00120-0 ARTICLE IN PRESS 1034 I. Schuder. et al. / Crop Protection 22 (2003) 1033–1038 2. Methods dish and mortality were recorded every 24 h for 2 days (with the slugs) and for 7 days (with the snails). Slugs (D. panormitanum) and snails (O. pfeifferi) were collected from field sites and from ornamental plant 2.2. Barrier against vertical movement nurseries, respectively. The potential repellent, barrier or antifeedant effects of 10 products were investigated Slugs were starved for 24 h prior to the experiment. (Table 1), using replicated laboratory bioassays. One slug was buried in each of 20 individual transparent SnailBans is an incinerated kaolin mineral and is plastic beakers (300 ml, 6 cm diameter) under a 2 cm available as a snail barrier on the amateur gardening layer of damp compost. The treatments were applied to market. Mypexs is a plastic woven matting and is the surface of the compost as a solid disc (metal foils and widely used in the horticulture industry to cover benches mattings), 6 mm-deep layer of material (minerals and and other production areas. Tex-Rs is a textile non- mulch) or 8 ml solution, respectively. The position of the woven matting with a copper-salt formulation bound to slugs and the damage caused to a 4 cm2 piece of Chinese a latex matrix. This matting is widely used in land- cabbage leaf (area eaten) on the surface were recorded scaping to suppress plant root growth. All bioassays every 24 h for 7 days. were carried out under identical laboratory conditions (15 C and 16:8 h light:dark). 2.3. Statistical analysis Two different approaches of applying products were used in laboratory experiments testing the effect of Binomial data were analysed with a G-Test. Multiple materials as a horizontal barrier (tested with slugs and comparisons of the control with all treatments were then snails) or a vertical barrier (tested with slugs only). In carried out based on the angular transformed propor- addition to the barrier effect, mortality and leaf damage tions (according to Zar, 1999). were recorded, providing data on the repellent, irritant Continuous data was tested for normality. Non- or antifeedant effects of the products. parametric data was analysed with a Kruskal–Wallis- Test and consequently with a post hoc procedure of multiple comparisons of the untreated compost with all 2.1. Barrier against horizontal movement treatments (Wilcoxon and Wilcox, 1964) as cited in Zar (1999). The slugs and snails were starved for 48 h prior to the experiment. Experiments were carried out in circular plastic dishes, 16 cm in diameter and filled with 2 cm of 3. Results damp compost. A 3 cm-wide strip in the middle of each dish was treated with one of the products (30 ml solution 3.1. Barrier against horizontal movement— or application of foil or mineral). A 4 cm2 piece of D. panormitanum Chinese cabbage was offered in one semicircle and two slugs or one snail were placed in the other. Slugs A significant barrier effect against horizontal move- weighing 150–400 mg and snails weighing 50–120 mg ment of D. panormitanum was observed with three were used. Pieces of cardboard (9 cm2) were provided as products (N=20, G-Test: Po0.001, Table 2). Garlic shelters. There were 20 replicate dishes per treatment. and ureaformaldehyde had a strong effect in repelling Leaf damage (cm2 eaten), position of the animals in the the slugs, with 65% and 72.5% barrier efficacy, Table 1 Products used in bioassays and their abbreviations in tables Product Type of product Concentration Abbreviation Untreated Compost n.a. UNT Aluminium Metal foil n.a. AL Cinnamamide Solution 1% CIN Copper Metal foil n.a. CU Croptex-Fungexs Copper ammonium 0.6% CF carbonate solution Garlic Solution 2.5% and 5% (horiz. and vert. barrier) GA Mulch Chipboard waste 1 cm depth MU Mypexs Horticultural matting n.a. MYP SnailBans Mineral 1 cm depth SB Tex-Rs Horticultural matting n.a. TEX Ureaformaldehyde Solution 6% UF ARTICLE IN PRESS I. Schuder. et al. / Crop Protection 22 (2003) 1033–1038 1035 Table 2 Table 3 Barrier efficacy of treatments against horizontal movement, mortality Barrier efficacy of treatments against horizontal movement, mortality of and damage (7SE) by D. panormitanum after 48 h. Treatment of and damage (7SE) by O. pfeifferi after 7 days. Treatment abbreviations as in Table 1 abbreviations as in Table 1 Treatment Barrier Mortality Damage Treatment Barrier Mortality Damage efficacya (%) rate (%) efficacy (%) rate (%) Accum. Reducedb Accum. (cm2) Reduced (cm2) (%) (%) UNT 0 3 6.670.4 x UNT 0 0 5.570.5 x AL 0 8 6.570.3 1 AL 0 5 2.970.3ÃÃÃ 46 ÃÃÃ CIN 10 15 5.270.4 41 CIN 35ÃÃÃ 20Ã 1.170.3ÃÃÃ 90 ÃÃÃ ÃÃÃ CU 25 5 3.970.6 60 CU 80ÃÃÃ 5 0.570.2ÃÃÃ 95 CF 0 3 2.770.5 21 CF 30ÃÃÃ 0 0.270.1ÃÃÃ 80 ÃÃÃ ÃÃÃ GA 65 0 0.370.1 95 GA 25ÃÃÃ 30Ã 0.770.2ÃÃÃ 88 ÃÃÃ MU 13 13 3.970.6 41 MU 55ÃÃÃ 10 1.770.5ÃÃÃ 70 MYP 0 0 5.570.4 17 MYP 0 5 3.070.4ÃÃÃ 46 SB 0 0 6.970.3 À5 SB 35ÃÃÃ 15Ã 1.570.4ÃÃÃ 72 ÃÃÃ TEX 0 15 2.870.3 58 TEX 5 5 1.970.4ÃÃÃ 66 ÃÃÃ ÃÃÃ UF 73 3 0.470.3 94 UF 90ÃÃÃ 20Ã 0.070.0ÃÃÃ 99 a ÃÃÃ Barrier efficacy: no damage occurred and no slug observed crossing Significantly different from the untreated compost, Po0.001. the barrier before the end of the experiment; ÃMortality significantly higher than with untreated compost, ÃÃÃ significantly higher than with the untreated compost, Po0.001. Po0.05. b Damage reduced: in comparison with the untreated compost; ÃÃÃindicates that accumulated damage over 7 days was significantly lower than with the untreated compost, Po0.001.