Comparative Bio-Pesticidal Efficacy of Citrus sinensis arancio Leaf and Peel Ethanolic Extracts Against Adult Periplaneta americana

Cockroach infestation poses serious public-health challenges due to their role in the mechanical transmission of pathogenic microorganisms. This study evaluated the comparative bio-pesticidal efficacy of Citrus sinensis leaf and peel ethanolic extracts against a total of seven hundred and twenty (720) adult Periplaneta americana under laboratory conditions. Ethanolic extracts of leaves and peels (5%, 10%, 15%, 20%) were tested for contact toxicity, fumigant activity, and repellency. Phytochemical screening revealed the presence of alkaloids, flavonoids, tannins, terpenoids, phenols, essential oils and limonoids, with peel extract exhibiting higher levels of limonene, flavonoids and volatiles. Mortality increased with concentration and exposure time. At 24 hours, leaf extract caused 64.0–100% mortality, while peel extract induced 74.7–100% mortality. Peel extracts acted faster, producing higher mortality at lower concentrations and earlier time points. Tukey HSD analysis showed no significant difference between leaf and peel overall (p = 0.2388), although variation existed among concentration groups (p < 0.05). Probit analysis showed LC₅₀ and LC₉₀ values of 11.8% and 17.9% for leaf extract and 9.4% and 15.2% for peel extract, confirming potency of the peel. Repellency was also dose-dependent, with peel extract (53–94%) outperforming leaf extract (44–91%). The findings demonstrated that both plant parts possess strong insecticidal and repellent properties, with peel extract exerting more rapid action. This study supports the use of C. sinensis extracts as eco-friendly alternatives to synthetic insecticides in cockroach management.