Two iron chelates, one toxic (iron 'butan') and the other not (iron 'octan'), were ingested by slugs (Deroceras reticulatum) at either a low (5 g kg(-1) diet) or a high (100 g kg(-1) diet) dose rate. In tissue sections of the digestive gland and body wall, iron was detected by energy-filtering transmission electron microscopy (EFTEM), using electron spectroscopical imaging (ESI) and electron energy-loss spectroscopy (EELS). The strongest signals for iron were obtained in secondary lysosomes of the resorptive cells in the digestive gland of slugs treated with a low dose of either compound, or with the high dose of iron 'octan'. At the cell apices of these cells, in endocytotic vesicles and in apically located lysosomes, iron was detected only in slugs fed with either dose of iron 'octan'. In slugs fed with the high dose of iron 'butan', iron could clearly be localised in the epithelial and mucus cells of the skin. The results are discussed with respect to differences in the toxicity of the two iron chelates. (C) 1999 Society of Chemical Industry.

Summary Extracts of 15 species of lichen were tested for antifeedant properties against the field slug Deroceras reticulation (Müller) (Mollusca: Pulmonata). All but three showed some activity and two of these were from endolithic species. The most effective extract was from Letharia vulpina. The major active compound from this species, vulpinic acid, was tested for dose response, applied as a foliar spray to turnip plants and as a dressing to wheat seeds in laboratory experiments. It provided effective protection against slug feeding under these conditions.

Test materials were incorporated in wheat flour pellets to measure their effect on slug feeding. The dry weights of individual pellets were measured before and after exposure for 24 h to starved slugs. The method gave consistent results, and can accommodate test materials with different physical properties. The phagostimulant effect of sucrose was confirmed. An extract of the herb tarragon (Artemisia dracunculus) was the most effective antifeedant of the materials used at the concentrations tested. The method is compared with other published techniques.

Individual adult beetles were confined in glass syringes (20 ml.) and mechanically stimulated by shaking. The plunger was then depressed so that the air in the syringe passed over the slug tentacle preparation. This was repeated several times with new slug nerve preparations. Two species of British Carabidae were tested: Pterostichus melanarius (Illiger), a common species found in many habitats including arable fields and known to prey on slugs, and Zabrus tenebrioides (Goeze), a herbivorous species which is an established pest of cereals in Europe and which occasionally damages crops in the UK.6 No spontaneous activity was recorded from the Application of stimulus

Indirect immunofluorescence assays were conducted on cryotome sections of four terrestrial slug species from three distinct phylogenetic groups, Arion ater (L.), Arion hortensis (Férussac), Tandonia (Milax) budapestensis (Hazay), and Deroceras reticulatum (Müller) using monoclonal antibodies for two glycosaminoglycans (GAGs), heparan sulphate, and chondroitin sulphate. Specific staining for a heparan sulphate-like component was demonstrated in the foot and tail regions of each species and was particularly intense in A. ater and A. hortensis, notably in the epidermis and associated mucus-like material, and in mucus-like material from the pedal gland region of the latter species. Subsequent studies with A. ater confirmed the presence of heparan-sulphate–like activity in the caudal gland duct region. No evidence of specific staining for chondroitin sulphate-like activity was found in any of the slug species. This work suggests that a specific GAG, or a group of closely related GAGs, is a common component of mucus in a range of slug species and of different types of mucus, including trail (pedal) mucus and the more viscous mucus produced by the caudal gland.

The ability of slugs (Deroceras reticulatum) to survive exposure to various chemical stressors such as molluscicides (carbamates, metaldehyde, iron-chelates) or other environmental pollutants (heavy metals, pesticides) was investigated using x-ray analyses, autoradiography, filter electron rnicroscopy, enzyme histochemistry, enzymatics, electron microscopy, and stress protein analyses. Uptake pathways, target sites, modes of action and general responses in the animnals were studied, and the results (including aspects of resorption and metabolism of the toxins as well as their cellular and biochemical effects ) interpreted in terms of both molluscicidal efficiency and of the consequences to slugs' ecological role as soil decomposers.

Grass and Forage ScienceVolume 49, Issue 1 p. 105-106 Yield response to insecticide treatment of a perennial ryegrass sward following sheep grazing or cutting by machine R.O. CLEMENTS, Corresponding Author R.O. CLEMENTS AFRC Institute of Grassland and Environmental Research, North Wyke Research Station, UKR. O. Clements, AFRC Institute of Grassland and Environmental Research, North Wyke Research Station, Okehampton, Devon EX20 2SB, UKSearch for more papers by this authorL.F. HENDERSON, L.F. HENDERSON Rothamsted Experimental Station, Harpenden, UKSearch for more papers by this author R.O. CLEMENTS, Corresponding Author R.O. CLEMENTS AFRC Institute of Grassland and Environmental Research, North Wyke Research Station, UKR. O. Clements, AFRC Institute of Grassland and Environmental Research, North Wyke Research Station, Okehampton, Devon EX20 2SB, UKSearch for more papers by this authorL.F. HENDERSON, L.F. HENDERSON Rothamsted Experimental Station, Harpenden, UKSearch for more papers by this author First published: March 1994 https://doi.org/10.1111/j.1365-2494.1994.tb01981.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Volume49, Issue1March 1994Pages 105-106 RelatedInformation

1. SDS-PAGE of trail mucus from seven species of terrestrial mollusc revealed few similarities in the pattern of protein or carbohydrate-containing bands.2. The trail mucus of the black slug, Arion ater L., contained 1 2% solids (9% protein, 21% hexose, 31% uronic acid, 39% hexosamine, 1% sulphate and < 1% sialic acid).3. The major carbohydrate fraction (50-100 kDa) after borohydride reduction of A. ater mucus, was shown by PAGE and FAB-MS to consist of long chains of a repeating disaccharide, probably HexNAc-HexUA. The linkage sugar between carbohydrate and protein was a hexosamine, GlcN(Ac) or possibly GalN(Ac).4. The carbohydrate fraction and whole A. ater mucus were susceptible to digestion with heparinase III, but not heparinase I, heparinase II, hyaluronidase or chondroitin sulphate ABC lyase, suggesting a structure similar to that of heparan sulphate.

In 1993, Rothamsted Experimental Station, the oldest agricultural research institute in the world, celebrated 150 years of experimental work on the production of farm crops. Most of the station's 'classical experiments', begun by its founder John (later Sir John) Lawes between 1843 and 1856, continue today and provide useful information for contemporary agriculture and ecology which Lawes could never have envisaged. These include development of a model for the turnover of organic matter in soil, assessments of the increasing pollution of soil by toxic metals and organic carcinogens resulting from twentieth century industrial activities, and insights into the ecological consequences of changes in agricultural policies. The experiments also provide many examples of the value of long term, systematic data collection and interdisciplinary research in agricultural production, ecology and environmental pollution. Facilities for this work became available through the scientific flair and foresight of Lawes, and since his death have been maintained and extended by generations of dedicated scientists.

Control of terrestrial slugs and snails by contact molluscicides acquired passively by crawling animals is potentially more efficient than the bait-delivery method currently used. An attempt was made to exploit the known molluscicidal activity of some common metals as contact-action poisons by comparing their rate of uptake and toxicity in different chemical forms. Uptake of iron and aluminium was faster from salt (sulphate)-coated than from chelate-coated surfaces and the rate of uptake also varied widely between chelates. Toxicity was dependent on metal uptake, but was modified by the ligand used. High mortality rates were associated with comparatively low metal uptake levels after contact with the lower members of an iron (III) pentanedionate and an iron (III) diazaalkanolate series of chelates.

The effects of seven potential phagostimulants and of four molluscicidal compounds on feeding were examined by confining slugs with agar gels containing the chemicals in varying concentrations. Sugars generally increased the amount of gel ingested; sucrose more than glucose, lactose and fructose. Feeding increased with increasing sucrose concentration to a maximum and then fell progressively: the optimum concentration lay between 2.5% and 5%. The sweeteners saccharin and aspartame at concentrations up to 2.5 % did not increase feeding. Addition of the molluscicides metaldehyde, methiocarb and ferric acetylacetonate to gels containing 2.5% sucrose progressively reduced feeding at concentrations of 0.001% and above. Metaldehyde reduced ingestion more than methiocarb and ferric acetylacetonate was intermediate. The molluscicidal herbicide Ioxynil deterred feeding completely at concentrations of 0.001%. The implications for slug bait development are discussed.

The present two field experiments, involving plots of Italian ryegrass sown in 1976, 1980 and 1984 confirmed results of earlier work in which the yield and persistence of Italian ryegrass was greatly increased by the application of pesticide. A range of pesticide treatments were used. The responses to application of permethrin applied three times per year average 8% for the three years of the first experiment and 5% for the five years of the second experiment. Such responses appeared cost-effective, but the overall environmental impact of such applications is not known.

The median lethal dose of a new molluscicide, aluminium acetylacetonate, was 646 mg kg−1 when forcibly injected into the gut of the slug Deroceras reticulatum (Müller). The mean dose voluntarily ingested by slugs which died after being confined with wheat flour bait containing the poison was equivalent to 1863 mg a.i. kg−1. The mean amount found in dead slugs collected from a grass/clover field treated with the bait was equivalent to 4797 mg a.i. kg−1.

SummaryA number of iron and aluminium compounds were compared as contact‐acting poisons against the slug Deroceras reticulatum, by confining slugs on treated surfaces of glass and wet soil in laboratory tests. Simple metal salts were effective poisons when applied to a glass surface, but were rapidly inactivated when applied to wet soil. Chelation of both metals with organic ligands retarded the rate of attenuation on wet soil. In a field trial D. reticulatum and Arion spp. slugs were killed by a broadcast application of the chelate iron (III) 2,4‐pentanedionate applied at 40 kg a.i. ha‐1.