Using Circular Open Field Thigmotaxis to Test Fermented Plant Extracts as Rat Repellents

We investigated the efficacy of five fermented plant extracts (kaffir lime, noni, garlic, chili and mint) as rat repellents, using circular open field thigmotaxis. Plants were fermented for 1, 3 and 5 days. Rats (Rattus rattus) were exposed to fermented plant extracts placed in the core zone (central area) of a circular open field. Rat behaviors in the field were observed for one hour and movements within the outer, middle and core zones of the field were recorded. Rats showed anxiety and aversion to the circular open field’s core zone. The average time (in minutes) that rats spent in the three zones was compared using a one-way ANOVA. Rats showed the highest aversion responses to noni and kaffir lime extracts. Calculation of thigmotactic ratios revealed that fermented noni and kaffir lime had higher scores than any of the other plants. Our results show that noni and kaffir lime could be used in rat repellent products, which would be low cost and environmental friendly.