The marsh slug, Deroceras laeve in Darjeeling Himalayas, India: First record and modelling of suitable habitats

Invasive slugs are a menace from the agricultural point of view apart from the impact on the native biota and the ecosystems. Subsequent to the observations of the marsh slug, Deroceras laeve in West Bengal, India, an attempt was made to confirm the species identity and the species distribution modelling considering the Himalayas of West Bengal and adjacent regions as the geographical distribution of the species. Assessment of the DNA barcoding of the COI gene confirmed the species as D. laeve with 99.84% similarity with a specimen of Canada. Owing to its record from the concerned regions, the prospective spread and the invasion of the species in similar regions were modelled using Maxent species distribution modelling. The result of species distribution modelling indicated that precipitation seasonality, precipitation of the driest month, snow coverage, elevation, and herbaceous vegetation had the most influence on the occurrence of D. laeve. The possible spread of the species can be expected in the future if congenial conditions are available in the extended geographical regions. As an invasive species, D. laeve may affect agricultural productivity apart from altering the habitat conditions and imposing competitive interactions with the native species. Based on the present observation, appropriate strategies may be framed for monitoring and regulating the spread of the invasive slug.