In vitro larvicidal activity of Kurthia gibsonii against the strongyle nematodes of sheep

A study was conducted to isolate bacteria from sheep dung and evaluate their nematocidal activity using an in vitro assay. The dung samples were collected from animals in two agro-climatic zones of Tamil Nadu, India, in 2024. The diluted faecal suspensions were first cultured in nutrient broth, and then a loop of the culture was streaked on a specific agar plate. The isolated bacteria were identified by cultural characteristics and Gram staining. A total of seven bacteria isolated in this study have been shown to possess varying levels of nematodicidal effects. One bacterium, which caused 100% (p<0.05) larval mortality (L1 and L2) within 4 hours at a concentration of 10% (p<0.05), was confirmed as Kurthia gibsonii by molecular analysis. At the lower concentrations of 5 and 7.5 % (p<0.05), it produced 100% larval mortality only after 6 hours of incubation. The results suggest that further studies are needed to evaluate the nematocidal potency of this bacterium under field conditions. This is the first report on nematodicidal activity of Kurthia gibsonii.