Efficacy of a Flonicamid-based formulation against the cotton leafhopper Amrasca biguttula biguttula on cotton, 2024

The leafhopper Amrasca biguttula biguttula was observed on cotton crops in Côte d’Ivoire during the 2022-2023 agricultural season, causing crop losses exceeding 50%. Faced with this critical situation, it is imperative to identify effective active substances. This study aimed to evaluate the effects of different flonicamid doses on the population of this pest and the damage caused to cotton plants. An experiment was conducted from June to November 2023 at a cotton research station in Bouaké, central Côte d’Ivoire. The experimental plots consisted of 10 rows of 10 m, covering an area of 80 m2. Three foliar insecticide treatments were applied at 14-day intervals using a knapsack sprayer with constant pressure and an output of 60 liter/ha. The products used, and their doses, are listed in Table 1. Observations of A. biguttula biguttula populations and damage were carried out at 3, 7, and 13 d after each treatment (3 days after treatment [DAT], 7 DAT, and 13 DAT, respectively). Thirty cotton plants were examined along the diagonal of the plot for each observation. Five terminal leaves were inspected to count the number of A. biguttula biguttula. A cotton plant was considered infested if any of these 5 leaves showed symptoms. The data were subjected to analysis of variance (ANOVA), and the means were separated according to Tukey’s HSD test. Means followed by different letters are significantly different (P ≤ 0.05, Tukey’s HSD). The data presented in Table 1 pertain to the progression of Amrasca biguttula biguttula populations and the mean number of infested plants following treatment. In terms of population density, the application of Floca 500 WG (flonicamid) at dosages of 100, 140, and 210 g/ha (equivalent to 50, 70, and 105 g a.i./ha, respectively) resulted in significantly reduced numbers (ranging from 4 to 18) compared to the insecticide THALIS 112 EC: emamectin-acetamiprid mixture (113 to 140 individuals) and the untreated control (123 to 153 individuals). The differences among treatments were statistically significant (P < 0.01) for all assessments conducted at 3, 7, and 13 DAT, thereby affirming the efficacy of flonicamid. Regarding plant damage, the mean number of infested plants was notably low in plots treated with flonicamid, with values ranging from 0.33 to 1.67 infested plants out of 30, contingent upon the dose. Statistical analysis results indicated that the 3 evaluated doses were equivalent in efficacy and demonstrated superior effectiveness compared to the emamectin–acetamiprid mixture, which performed similarly to the untreated control. Observations further reveal that flonicamid doses (50, 70, and 105 g a.i./ha) effectively controlled A. biguttula biguttula for a minimum of 14 d. This work was funded by the Interprofessional Fund for Agricultural Research and Advisory Services (FIRCA) and the Interprofessional Organization of the Cotton Sector (INTERCOTON) of Côte d’Ivoire, as part of the search for solutions against the invasion of Amrasca biguttula biguttula. None declared.