Evaluation of palatability of 20 plant species as a food source for slugs Deroceras reticulatum (Mi.iller), Arion lusitanicus (Mabille) and Arion ruf us (Linnaeus) was performed under laboratory conditions in tests with multiple choices and without choice. Rate and degree of damage of seedlings and leaves of matured plants of herbs and winter oilseed rape were calculated. Based on conducted experiments, plant species preferred and rejected by particular slug species were defined. Plants that were preferred by all examined slug species were the following: Brassica napus, Conium maculatum and Lamium amplexicaule. Rejected plants were Polygonum nodosum and Plantago lanceolata. Slugs have showed differentiated preferences towards the remaining plant species.

The intensity of Arion lusitanicus occurrence and the damage degree of 31 crop species have been estimated. It has been found that the slug damaged lettuce and cabbage plants very heavily (Lactuca sativa L. var. capitata L., Brassica oleracea L. var. capitata L. f. alba) and many species of other vegetables (Cucumis sativus L., Phaseolus vulgaris L., Raphanus sativus L. subvar. radicula Pers.). Plant damages in the edge strips were also observed on rape and barley plantations attacked by this slug. The moving activity of particular individuals of Arion lusitanicus was varying. Planning of the experiments in a nested block design has made it possible to statistically determine tendencies of the slug movement. It was observed that when some individuals remained at the point where they were initially placed, others, 2 hours after, moved over 7 m away. The mean weighed length of pathway covered by a single individual and the mean movement rate of one were estimated for each of 9 observation dates. It has been found that slugs penetrating the site surface under observation displayed their tendencies to move towards more moist places and towards food sources.

Studies on food preference of herbivores include no-choice test and test with choice or multiple choice. Conclusions from statistic analyses of these tests are compared descriptively. The definition of compatibility index and consumption growth index has enabled us to use nonparametric test for verification of hypotheses about homogeneity of the consumption growths of selected plant species under no-choice and multiple choice conditions. The studies were conducted on food preference of the slug Deroceras reticulatum. It has been found that Chamaenerion angustifolium, Geraniumpusillum and Potentilla anserina can be used to reduce this slug feeding on cultivated plants. It has been also found that seedlings of Polygonum aviculare can be used as alternative food for slugs.

Studies on palatability of some commom weed species, herbaceous plants and oilseed rape to D. reticulatum, A. lusitanicus and A. rufus slugs have been carried out under laboratory conditions. In food choice trials the rate and degree of damage to seedlings and leaf disks were determined for 20 plant species. The conducted experiments have also permitted to establish, which plant species were preferred or were not accepted by particular slug species. It was found that the studied slug species preferred seedlings and leaves of Brassica napus and Papaver rhoeas, but showed no preference for Epilobium hirsutum, Geranium sanguineum and Saponaria officinalis plants. As to the remaining plant species under study, the preferences exhibited by particular slug species were quite diverse.

Vegetables in addition to arable crops and ornamentals are also at high risk from slug and snail attack at all growth stages. The no-choice tests were conducted under laboratory conditions to assess the harmfulness of the slug Arion rufus (Linnaeus) and the snail Cepaea hortensis (Müller) to young vegetable plants. Ten species representing leaf and root vegetables, allium, brassica, cucurbit and edible pulse plants were chosen to compare their susceptibilities to feeding of these pests (agrotechnical classification – Polish National List of Varieties of Agricultural and Vegetable Plants 2005). The evaluation of the growth of the tested vegetables included a percentage of the damaged plant area and changes in aboveground plant mass. The trend toward increase of mass was defined by the means of regression analysis. Losses of aboveground plant mass resulting from pest feeding and plant growth restraint caused by the slug or the snail damage were assessed. Variance analysis of the general linear model and orthogonal contrasts were calculated to compare the vegetable groups included in the research. The highest losses of aboveground plant mass, by both pest species A. rufus and C. hortensis, were on common bean plants and the smallest on plants of leaf vegetables (lettuce, dill), brassica plants (cauliflower, white cabbage) and allium plants (garden onion).