Quinestrol nanoparticle-based formulation for long-term oral contraception against the wild female rats, Bandicota bengalensis

This study developed and evaluated a ready-to-use quinestrol nanoparticle-based bait for contraception in female Bandicota bengalensis (lesser bandicoot rat). B. bengalensis in three treatment groups: Control (plain bait), Q (bait with bulk quinestrol, 100 ppm), and QNP (bait with quinestrol nanoparticles, 10 ppm) were evaluated at 15, 45, and 75 days after a five-day treatment in a bi-choice setting. Results showed no significant difference between treated and plain bait consumptions, indicating good acceptability. Ovary weight decreased, and uterine weight increased significantly in the treated groups. Organ histology revealed significant contraceptive effects, including an increased number of atretic follicles, a reduced number of normal follicles in the ovaries, and increased uterine gland numbers and diameter. The 17β-hydroxysteroid dehydrogenase and 3β-hydroxysteroid dehydrogenase activities were significantly increased. Treated females produced 65–85% fewer pups when bred with untreated males. Quinestrol did not affect body weight, weight of vital organs, the activity of alkaline and acid phosphatases, and aspartate and alanine aminotransferases, indicating its safety. The effects of Q lasted up to 45 days, whereas the effects of QNP persisted for 75 days, despite using 10 times less active ingredient. This research represents a potential advancement in sustainable rodent pest management with extended efficacy and reduced dosage requirements.