Methyl anthranilate (MA) is a known nociceptive bird repellent. The present study was conducted to determine the histopathological effect of methyl anthranilate causing gastrointestinal malaise and thus conditioned taste aversion in house rat, Rattus rattus, which is a known rodent pest worldwide. Both mature male and female rats were fed on 2.5% MA treated bait continuously for 30 days under laboratory conditions. Histomorphometric studies showed that consumption of MA treated bait causes a significant reduction in the thickness of different layers of the stomach and intestinal wall. Vacuolization in the stomach and intestinal mucosa was also recorded, which resulted in a significant reduction in the number of cells present in intestinal and gastric glands. Histopathological studies also revealed focal hyperplasia with keratin pearl, squamous cell papilloma, and mucosal cysts in the lumen of the non-glandular region of the stomach of rats. Present studies confirmed that gastrointestinal tract was severely affected in rats fed on 2.5% MA treated bait. In the future, methyl anthranilate based repellent formulations can be developed to induce condition taste aversion in the rats to repel them for long period in commensal situations

Methyl anthranilate; gastrointestinal tract; Rattus rattus; histopathology

From the present study, it is concluded that 2.5% MA severely affected the gastrointestinal tract causing gastric distress (secondary repellent effect) in house rats. Therefore, exposure of rats to 2.5% MA treated bait can induce condition taste aversion (CTA) against MA leading to avoidance towards its smell for a long time. Earlier studies conducted in our laboratory also reported its olfactory and gustatory repellent (Primary) effects

Bindu Bala and Bhupinder Kaur Babbar (2025). Development of Gastrointestinal Distress in Rattus rattus Against Methyl Anthranilate: A Bird Repellent. Biological Forum, 17(6): 30-37.