Bio-insecticidal effects of essential oil nano-emulsion of Lippia multiflora Mold. on major cabbage pests

The present study investigated the potential use of the nano-emulsion of Lippia multiflora Mold. essential oil in managing the cabbage pest (Brassica oleracea L.) in two Ivorian areas (Yamoussoukro and Korhogo) during the wet seasons (April-September 2018). The nano-emulsion was tested against cabbage diamondback moth (Plutella xylostella), aphid (Brevicoryne brassicae), webworm (Hellula undalis), cutworm (Spodoptera exigua) and whitefly (Bemisia tabaci) under field conditions. The efficacy of essential oil emulsion was compared with the synthetic pesticide Karate 5 EC (Lambda cyhalothrin 52 g · l–1). The results indicated that the nano-emulsion of essential oil gave better control of the cabbage insect pest than the untreated plots. For all the insects studied, the nano-emulsion was very effective towards the species B. brassicae and P. xylostella for which the reduction of the mean population was respectively, 28.48 ± 0.2 and 0.6 ± 0.02 in Yamoussoukro and 0.0 and 7.11 ± 0.16 in Korhogo, compared to 45.32 ± 0.43 and 15.89 ± 0.23, respectively, for untreated plots. The yields of cabbage heads obtained in both areas Yamoussoukro and Korhogo were 4.7 and 15, respectively. The head damage percentages were 23.3% in Yamoussoukro and 26.7% in Korhogo when the fields were sprayed with nano-emulsion and were 13.3% and 28.3%, respectively, when the cabbages were treated with the synthetic pesticide. The formulation obtained here might be an interesting alternative for integrated pest management of cabbage.