Michael Qwarse¹, Matobola J. Mihale^1,, Leonia Henry², Joseph Sempombe³, Veronica Mugoyela³, Fortunatus Sung'hwa⁴

This study assessed the pesticidal activities of Phytolacca dodecandra extracts in controlling Sitophilus zeamais and Tribolium castaneum pests in stored maize grains. The study was conducted at ambient conditions (25–30°C and 65–70% relative humidity) and designed in a completely randomised design with 8 treatments in triplicate. Contact toxicity, percent mortality, feeding deterrence and grains weight loss were assessed using developed procedures for 21 days and first filial generation progeny was assessed for 42 days of post-pest introduction. Both ethanolic root and leaf extracts of P. dodecandra demonstrated significant bioactivities against both S. zeamais and T. castaneum, with the leaf extract being more active than the root extracts. P. dodecandra leaf extracts killed 98% of S. zeamais and 99% of T. castaneum at concentration of 150 mg/mL on day 3. Similarly, P. dodecandra leaf extracts reduced grain damage to 0% and had moderate repellence of 57% and 66% to S. zeamais and T. castaneum, respectively. Hence, after biosafety studies this plant-based products can be included in the Integrated Pest Management strategies and can be recommended as an alternative remedy in treating maize storage pests in subsistence agriculture. Further isolation and structure elucidation of bioactive ingredients in the plant species are recommended and are underway.

Pesticida Activity, Phytolacca dodecandra, Mbulu, Tanzania, Sitophilus zeamais, Tribolium castaneum, maize