Population dynamics of the leafhopper Jacobiasca lybica (Hemiptera: Cicadellidae) within vineyards and citrus orchards of Morocco

Abstract

The population dynamics of Jacobiasca lybica were monitored in different grapevines cultivars, citrus trees, and windbreak trees and the planning of insecticide treatments based on the recorded degree days (DD) was investigated. The study was conducted in Berkane province of Morocco during 2019, 2020 and 2021, using five yellow sticky traps for each experimental unit that were collected weekly for identification and counting of leafhopper adults. The leafhopper population fluctuated within vineyards, citrus trees and windbreak trees according to temperature recorded where three to seven overlapping peaks of adult flight were observed until September in 2019 and 2021, while a total of ten generations were predicted according to DD until December in 2020. The incidence started to appear clearly on Carignan during July of each year, but on Syrah it appeared only at August to reach 100% of incidence. These periods coincide with the nymph peaks that were higher on Carignan than Syrah. The leafhopper preference to Acacia trees over Cypress trees was observed for all years. Finally, the leafhopper population was decreased after the insecticides applications that were planned mostly after the week following the achieved DD. This technique is discussed as a promising technique to apply the control measures at the correct time.