Control of fall armyworm (Spodoptera frugiperda) with lemon basil (Ocimum africanum) in Tolon, northern region of Ghana

The use of synthetic pesticides to control pests often comes at the expense of environmental and human health. To address this in recent times, botanicals prepared from local herbs have been used as an alternative management option because of their relatively safe and environmentally friendly nature. In line with that, we tested for the efficacy of a botanical formulation prepared from wild lemon basil (Ocimum africanum Lour.) on Fall Armyworm (FAW) on the field. The O. africanum formulations used for the study were sun dried powder (SUDP), Sun dried water extract (SUDWE), shade dried powder (SHDP) and shade dried water extract (SHDWE). We applied a mixture of 250 g of the O. africanum material in a 15-liter knapsack sprayer separately of each formulation to sixteen (16) 5 m × 5 m plots of maize stands in a Randomized Complete Block Design (RCBD) with four (4) replications and four (4) treatments. The main parameters used to assess the efficacy of the botanicals under study were, damage severity of the worm on maize plants, abundance of live worm and count of mortality of the worm on the experimental plots. Our results showed that lemon basil negatively affected the FAW population by increasing mortality (approximately 65% for SUDP, 85% for SUDWE, 60% for SHDP and 82% for SHDWE) on treated plots compared to untreated plots with a reduced live population leading to enhanced protection of the maize stands, although water extract formulations performed better than powdered ones. We recommend that awareness be created in maize producing areas with an abundant wild lemon basil plant to conduct several tests with different preparations from different parts of the plant to document the impact on FAW to encourage using such extracts to control FAW as an alternative to synthetic pesticides.