Biopestcidal Potentials of Erythrophleum Africanum (Benth.) Harms Stembark and Leaf Extracts for the Management and Control of Termites

Abstract

Background Environmental concerns over the use of large quantities of synthetic insecticides for termite control owing to the huge pollution burdens and modern environmental health hazards (MEHH) of such chemicals on non-target living beings and other environmental element. To reduce the burden of such chemicals on the environment, the use of plant-based extracts to control termites could be an effective alternative if properly explored. One such plant with potential for anti-termite activity was assessed in this study. Result The phytochemical evaluation indicated high presence of alkaloids, cardiac glycosides, flavonoids and steroids in the stem-bark, while anthraquinones, saponins, tannins and terpenes were observed in the leaf extract. The GC-MS analysis revealed the presence of twenty-five compounds and thirty-four compounds in the leaf and stem bark extract respectively. On the other hand, the termiticidal activity of the leaf and stembark extracts was more against Reticulitermes flavipes Kollar (Subterranean) termites than Reticulitermes tibialis (Arid Land Subterranean) termites. Further study revealed that a concentration of 30.35 mg/L and 183.31 mg/L of the leaf extract was required to knock-off 50% and 90% of the Reticulitermes tibialis termites respectively, while a concentration of 40.76 mg/L was required to knock-off 50% and 66.19 mg/L is needed to knock-off 90% of the Reticulitermes flavipes Kollar termites Similarly, for 50% of the Reticulitermes tibialis termites to be knocked-off, 48.20 mg/L of the stembark extract was required. To achieve higher mortality of the termites (90%) of the Reticulitermes tibialis termites, 243.26 mg/L of the stembark was required. Concentrations of 33.24 mg/L and 54.35 mg/L of the stembark were required to knock-off 50% and 90% of the Reticulitermes flavipes Kollar termites respectively. E. africanum ethanol leaf and stembark extracts can be classified as Category 4 which gives the indication of moderate acute toxicity hazard. Conclusion E. africanum extract will therefore, serve as a safe, efficacious and environmentally friendly pesticide for use against termites.