Chemical Composition, Antioxidant Activity, Cholinesterase Inhibitor and in Vitro Insecticidal Potentiality of Essential Oils of Lippia multiflora Moldenke and Eucalyptus globulus Labill. on the Main Carpophagous Pests of Cotton Plant in Ivory Coast

Abstract

The abusive and repeated use of synthetic chemical insecticides has proven to be harmful to human health and the viability of the cotton production system in Ivory Coast, so it is imperative to find alternatives. . Thus, the objective of this study was to study the chemical composition and biological activity of essential oils of Lippia multiflora (Verbenaceae) and Eucalyptus globulus (Myrtaceae) and to evaluate their insecticidal potential in the laboratory on three main pests of cotton. After essential oils extraction, their chemical composition was determined. Also, antioxidant activity and cholinesterase inhibitor of essential oils were evaluated. After that, different concentrations of the two essential oils were prepared and applied by contact on groups of insects constituted by ten. The essential oil of L. multiflora was the most toxic for the three pests tested. Indeed, the lethal concentrations (LC50) were 1.74 %, 1.39 and 7.20 %, respectively, on Pectinophora gossypiella, Thaumatotibia leucotreta and Helicoverpa armigera. In contrast, the values obtained with E. globulus essential oil were nine to two times greater (16.05 %, 10.23 % and 16.32 %, respectively on these pests). With respect to the chemical composition of the essential oils, E. globulus essential oil was the richest in oxygenated monoterpenes (65 %) with 1,8‐cineole or eucalyptol as the majority compound (61.6 %). The essential oil of L. multiflora was distinguished by a lower proportion of oxygenated monoterpenes (44.3 %), but it contained more terpene elements (24 vs. 15 for the essential oil of E. globulus). The essential oils of L. multiflora and E. globulus also showed significant inhibition of acetyl (2.13 and 2.16 mg galantamine equivalent (GALAE)/g, respectively) and butyryl cholinesterase (4.03 and 3.61 mg GALAE, respectively). L. multiflora was differentiated by its good inactivation of tyrosinases (163.46 versus 58.95 mg kojic acid equivalent (KAE)/g in E. globulus). Better antioxidant activity was observed with L. multiflora essential oil relative to DPPH (7.05±0.34 mg trolox equivalent (TE)/g). Biopesticides based on L. multiflora essential oil could be developed for the phytosanitary protection of cotton plant.

In Vitro and Molecular Docking Evaluation of Larvicidal Effects of Essential Oils of Five Aromatic Plants on the Fall Armyworm Spodoptera frugiperda JE. Smith (Lepidoptera: Noctuidae) from Ivory Coast

“…Indeed, for all essential oils, increasing concentrations led to an increasing evolution of mortality in the batches of caterpillars. This fact was the same when testing the sensitivity of adults of Pectinophora gossypiella , a carpophagous insect of cotton, with the same essential oils [12–14] . Our observations are in line with those of Akantetou et al.…”

“…This fact was the same when testing the sensitivity of adults of Pectinophora gossypiel-la, a carpophagous insect of cotton, with the same essential oils. [12][13][14] Our observations are in line with those of Akantetou et al. [15] Indeed, these authors revealed the well-marked positive evolution of average mortality rates with increasing concentration of essential oil of O. canum and O. basilicum and regardless of the duration of aphid exposure.…”

“…This gauze film represents the support for the oviposition of the females. After the females mated and laid their eggs, the gauze was placed on the underside of the lids of a rectangular box containing artificial nutrient medium of known composition [13] . After the eggs hatched, the neonate caterpillars had direct access to their food, which they easily reached.…”

“…After the females mated and laid their eggs, the gauze was placed on the underside of the lids of a rectangular box containing artificial nutrient medium of known composition. [13] After the eggs hatched, the neonate caterpillars had direct access to their food, which they easily reached. These larvae constituted the generation (G1) of reared individuals and were the focus of the bioassays.…”

Phytochemical profiling, antioxidant activities, enzymatic activities and insecticidal potential of aqueous extracts of four plants on the larvae of Helicoverpa armigera (Lepidoptera: Noctuidae), the main pest of cotton plant in Ivory Coast

“…Any individual that moves and moves normally was considered alive (Doffou, 2012). If mortality in the control batch was greater than or equal to 10%, the test was rejected or when dead or moribund insects were observed among the controls, mortality rates were corrected by the Abbott (1925) formula: T A B L E 1 Composition of the artificial nutrient substrate for rearing H. armigera (Kobenan et al, 2022). As a first approximation, we must admit that the lethal toxic effects, resulting from the contamination of the food, depend on the concentration (C) of the aqueous extracts in it and on the duration of exposure (T) to this concentration, following Haber's law: When there is at least one study of sufficient quality for the exploitation of the experimental results retained for the lethal effects, the model f, will be the statistical model "probit" (Finney, 1971).…”