How do slugs cope with toxic alkaloids?

Abstract

Arion lusitanicus and other slugs are able to feed on a variety of plants, even those containing toxic secondary metabolites, such as alkaloids. Alkaloids, like sparteine, lupanine, quinidine and atropine are avoided in no-choice feeding experiments only when they are present in concentrations above 1 mg/g food pellet. Alkaloids (sparteine, lupanine, cytisine, quinidine, atropine, senecionine, eserine, and harmaline) are toxic to Arion lusitanicus when injected. LD 50 values are 10 to 20 fold higher than in vertebrates indicating that slugs have a high tolerance towards food toxins. The tolerance is higher in young animals than in adult slugs. Injected alkaloids are rapidly detoxified within 72 h. Tolerance and detoxification can be induced by feeding slugs on non-lethal doses of lupin alkaloids. Using isolated microsomal preparations from the digestive gland, active detoxification was observed in vitro. Evidence is presented that cytochrome p450 plays an important role in detoxification of the applied alkaloids. A powerful and inducible detoxification systems appears to be the main mechanism that allows slugs to feed on plants rich in secondary metabolites (when no other food is available), that are usually avoided by other herbivores.

Glycoalkaloid composition explains variation in slug resistance in Solanum dulcamara

“…By utilizing a metabolomics approach to analyse the underlying chemical mechanisms, we identified four prominent steroidal glycoalkaloids (GAs) showing particularly strong negative correlations with slug feeding preference. This is in line with previous studies reporting toxic or repellent effects of different types of alkaloidal secondary metabolites to gastropods (Aguiar and Wink 2005; Bog et al 2017; Speiser et al 1992; Wink 1984) and insect herbivores (Altesor et al 2014; Hare 1983). …”

“…However, gastropods may also be able to endure toxic substances. Some gastropod species have been shown to possess effective microsomal detoxification mechanisms to cope with alkaloids to a certain extent (Aguiar and Wink 2005). The same authors suggested that cytochrome P450 oxidizing enzymes play a central role (Aguiar and Wink 2005).…”

“…Some gastropod species have been shown to possess effective microsomal detoxification mechanisms to cope with alkaloids to a certain extent (Aguiar and Wink 2005). The same authors suggested that cytochrome P450 oxidizing enzymes play a central role (Aguiar and Wink 2005). However, further experimental testing of GA metabolism, for example by feeding labelled GAs to slugs, is necessary to support this hypothesis.…”

Molluscan biological and chemical diversity: secondary metabolites and medicinal resources produced by marine molluscs

“…Some novel terpenes that inhibit HIV‐1 reverse transcriptase have been isolated from extracts of the giant African snail Achatina fulica (Patil et al , 1993) and cardioexcitatory peptides have been identified from the freshwater snail Lymnaea stagnalis (Tensen et al , 1998). There is evidence that some terrestrial pulmonate snails can sequester bioactive terpenes from their lichen diets (Hesbacher et al , 1995) and terrestrial slugs, such as Arion lusitanicus, have been shown to sequester and detoxify alkaloids from a variety of plants (Aguiar & Wink, 2005). These studies highlight the potential for further discoveries within the natural products and chemical ecology of terrestrial pulmonates.…”

Bioactivity of the Alkaloids, Norharman and L-N-Methylcrotonosine/Linearisine

“…The production of excess mucus is an indicator of poisoning in slugs but they are known to be well equipped to detoxify poisons (Aguiar and Wink, 2005). In this study, it is possible that the slugs detoxified the initial quantity of toxicant absorbed and then secreted mucus to prevent further contact with the toxicant or to nullify its effects.…”