Multiple Introductions of the Pestiferous Land Snail Theba pisana (Müller, 1774) (Gastropoda: Helicidae) in Southern California

Bio-molluscicidal potential and biochemical mechanisms of clove oil and its main component eugenol against the land snail, Theba pisana

The land snail, Theba pisana is a serious pest that adversely affects various crops in sustainable agriculture. Essential oils and their constituents represent an environmentally sound alternative to synthetic pesticides. Our study aimed to investigate the lethal and sub-lethal toxicity of clove oil and its main component eugenol to understand the mechanisms underlying its toxic action against T. pisana. The GC-MS profile of the clove oil composition was characterized. In the laboratory experiment, LD₅₀ of clove oil and eugenol via the contact testing were determined after 48 and 72 h. Moreover, sub-lethal effects of clove oil or eugenol on the survivors following the exposure of snails to the 25 and 50% of the LD₅₀/48 and 72 h were evaluated through using snail tissues for biochemical measurments. The GC-MS analysis showed that eugenol (64.87%) was the major constituent present in the oil. The results also showed that LD₅₀ values at 48 and 72 h were 2006.5 and 1493.5 μg/g b.w for oil and 239.6 and 195.3 μg/g b.w for eugenol, respectively. Compared to control, the sub-lethal effects of clove oil or eugenol at 48 and 72 h showed a significant increase in reduced glutathione (GSH) levels. Catalase (CAT) and glutathione-S-transferase (GST) activities significantly elevated in oil- or eugenol-treated snails, except at low dose after 48 h. After two exposure times, snails exposed to oil or eugenol at both sub-lethal effects had considerably higher γ-glutamyltransferase (γ-GT) and aspartate aminotransferase (AST) activities. Moreover, markedly augmentation in alkaline phosphatase (ALP) and alanine aminotransferase (ALT) activities at all exposure times, with the exception of snails treated with low dose of eugenol after 48 h was observed. Both clove oil and eugenol at the tested doses caused a significant inhibition in acetylcholinesterase (AChE) activity at two exposure times. Our findings highlight the potential of clove oil and eugenol, as an efficient natural molluscicide alternative to its synthetic counterparts for snail control.

First record of the genus Xeropicta Monterosato, 1892 (Gastropoda: Eupulmonata: Geomitridae) in Serbia

Xeropicta Monterosato is a pulmonate xerophilous snail genus of the family Geomitridae. It is distributed in the eastern Mediterranean and the Black Sea region and also in Asia Minor, Ukraine, the Caucasus, the Middle East and Iran. No species of this genus was known from Serbia until now. Here, we present the first record of Xeropicta from Serbia. Morphological, anatomical and ecological characteristics of the species as well as its variation are discussed. Because of the wide shell variation, the analysed specimens were identified based on anatomy, and correspond to X. krynickii. However, in their shell morphology, some specimens resemble X. derbentina. Therefore, here they are treated as X. cf. krynickii. Further studies should shed more light on their identity.