In recent years, jassids have become a problem for cotton and the current control program for this pest seems ineffective. This study was therefore initiated with the objective of evaluating the effectiveness of three new phytosanitary protection programs against jassids. Trials were conducted at the Nambingué observation post. The study designs were Fisher blocks with 5 objects and 4 replications. Each elemental plot had a length of 10 m and a width covering 10 lines, 8 of which were treated. The spacing between rows was 0.8 m. The distance between patches on a line was 0.4 m. The distance between blocks was 2 m. Six insecticide treatments were carried out. Treatments were started on the 45th day after cotton emergence, at 14-day intervals. These three new programs, which differ according to the composition and positioning of the active substances, were tested during two years in a fisher block design with four repetitions. Two programs, labelled programs B and C, had an efficacy threshold greater than 80%. Program B was characterized by a positioning spiromesifen or chlorantraniliprole in T1 and T2, cypermethrin + abamectin in T2 and T3 and spinetoram + sulfoxaflor in T5 and T6 respectively. And program C was characterized by a positioning spinetoram + sulfoxaflor in T1 and T2, Deltamethrin + chlorpyrifos ethyl in T3 and T4 and dinotefuran 14% + alphacypermethrin 22% in T5 and T6 respectively. They both contributed to a significant reduction in jassid outbreaks during the two years of experimentation. Programs B and C can be used as an alternative to the extension program to manage resistance.

The aim of this study is to highlight the diversity of leafhopper species and their impact on the cotton crop in Côte d'Ivoire. The collections made in 2021 allowed the identification of three species. Jacobiasca lybica is the most abundant, with proportions ranging from 73.3–93.3% depending on the site. The other two species are respectively Empoasca papayae (8.3%) and Jacobiella (= Empoasca) facialis (5%). In 2022, collections revealed the invasion of a new species, Amrasca biguttula, which became dominant with proportions of 90 to 100% depending on the site. Two other species J. lybica (2.7%) and J. facialis (1.3%) cohabit with A. biguttula. Thus, if the damage noted in 2021 was attributable to J. lybica, that observed in 2022 is essentially due to A. biguttula. The northeastern part of the cotton basin was the area most affected by attacks by these two new species. This zone seems to be favorable to the outbreak of leafhopper because of the low rainfall recorded in the localities. The results of the study reveal significant changes in the composition of leafhopper species in the cotton production areas of Côte d'Ivoire from one year to the next. This situation also explains the variations in damage levels. This raises the problem of adapting the phytosanitary protection programs applied by the producers.

In recent years, a change in the spatiotemporal profile of leafhopper populations has been observed, resulting in persistent infestations in cotton parcels throughout the crop cycle. The need to investigate the various causes of this change led to the present study, which aimed at identifying the leafhoppers found on cotton in the Ivorian cotton basin. Collections were made in 12 localities of the cotton basin. The identification of these samples revealed the existence of at least three species of leafhoppers. These are Jacobiasca lybica (Bergevin & Zanon, 1922), Empoasca papayae (Oman, 1937) and Jacobiella fascialis (Dworakowska, 1972). The first two species mentioned were not previously known on cotton in Côte d'Ivoire. The three species cohabit in the same cotton parcels, with a predominance of J. lybica (70 to 97%). This study thus highlights a probable diversity of leafhopper species present on cotton.