Population ecology of leafhopper Jacobiasca lybica (Bergevin & Zanon, 1922) (Hemiptera: Cicadellidae) and its control based on degree-days in Moulouya area of Morocco

The cotton leafhopper (Jacobiasca lybica) is one of the polyphagous species and its control is mainly based on chemical treatments, however its bio-ecological parameters are still poorly understood especially under Moroccan conditions. In this work, the population ecology of this leafhopper and the planning of insecticide treatments based on the recorded degree-days (DD) in a citrus orchard and vineyard separated by a windbreak (WB) of Cypress and Acacia were investigated. Leafhopper adults were monitored with five yellow sticky traps for each experimental unit and removed weekly from April to August for identification and counting. The sampling indicated the presence of five peaks of adult flight during 2017 and seven during 2018. Whereas six generations were predicted each year according to DD recorded until mid-August. Leafhopper populations were present on WB plants throughout the study period, and its preference for Acacia over Cypress was observed. During 2018, insecticides used were applied one week after DD predicted new generations on WB plants, and they were also applied on grapes at second, third, fourth and fifth adult peaks. The use of DD to predict the outbreak of new generations is discussed as a promising strategy to manage leafhopper populations below economic thresholds.