INSECTICIDAL POTENTIAL OF OLEANDER (NERIUM OLEANDER) AND MINT LEAVES (LAMIACEAE FAMILY) POWDER AGAINST THE AMERICAN COCKROACH (PERIPLANETA AMERICANA)

Abstract

This study evaluated the insecticidal efficacy of Nerium oleander and Mentha spp. leaf powders individually and in combination against the American cockroach (Periplaneta americana) under laboratory conditions. Plant materials were collected from Adarawa and Shama villages within the permanent site of Usmanu Danfodiyo University, Sokoto, located in the Sudano-Sahelian ecological zone of Northwestern Nigeria. Fresh leaves were authenticated, shade-dried, pulverized, and stored for bioassay experiments. Adult P. americana were collected from infested residential and commercial areas, acclimatized for 5–7 days, and exposed to three concentrations (0.5 g, 1.0 g, and 1.5 g) of each plant powder using a completely randomized design. Mortality and behavioral responses were monitored at 6, 12, 24, and 48 hours over a four-day exposure period. Qualitative phytochemical screening of the powders revealed the presence of flavonoids, tannins, saponins, alkaloids, glycosides, steroids, terpenoids, and phenols in varying amounts, while anthraquinones were absent in both plants. Results showed that mint powder produced the highest cumulative mortality (60%), followed by the combined treatment (50%), while oleander powder caused 40% mortality; the control recorded 0% mortality across all days. Mint demonstrated earlier and stronger toxic effects, indicating higher insecticidal potential. The findings suggest that Mentha spp. and Nerium oleander, especially when combined, possess phytochemicals capable of exerting significant insecticidal activity and may serve as environmentally friendly alternatives for managing cockroach infestations.