FURTHER DATA ON SCALE INSECT SPECIES IN AN ORGANIC CITRUS ORCHARD IN NORTH-EASTERN TUNISIA: BIODIVERSITY, ABUNDANCE AND NATURAL ENEMIES

Abstract

Elimem M., Jendoubi H., Lahfef C., Limem-Sellemi E., Ben Belgacem L., Kalboussi M., Rouz S. - Further data on scale insect species in an organic citrus orchard in north-eastern Tunisia: biodiversity, abundance and natural enemies. Faunistic studies on pests are always needed to update checklists of species in a country and enlighten the emergence of new potential species. A survey was carried out on the scale insect fauna of citrus and associated natural enemies in an organic orchard from the north-eastern of Tunisia (Zaghouan province). The occurrence, incidence, dominance and biodiversity parameters for each scale insect species were recorded. Samples of infested fruits, leaves and twigs (8 400 samples and 416 053 coccids) were collected at random from the citrus grove during three years (2017, 2019 and 2021). Eight scale insect species belonging to four families were identified: Aonidiella aurantii Maskell (1879), Parlatoria ziziphi Lucas (1853) (Diaspididae); Planococcus citri Risso (1813) (Pseudococcidae); Ceroplastes floridensis Del Guercio (1900), Coccus hesperidum Linnaeus (1758), C. pseudomagnoliarum Kuwana, Saissetia oleae Olivier (1791) (Coccidae) and Icerya purchasi Maskell (1878) (Monophlobidae). The eudominant species was P. ziziphi, presenting the highest densities (98.8%) during all the period of survey. The other coccids were classified as subrecedent species. The natural enemy fauna was limited to two coccidophagous species of ladybirds; Chilocorus bipustulatus Linnaeus (1758) which was the most dominant species and Rodolia (Novius) cardinalis Mulsant (1850). Records on scale insect fauna in Tunisia is enough completed within the citrus crop but should be extended to other fruit trees and ornamental plants. The checklist of coccids in Tunisia needs regular investigations. Key Words: Citrus, scale insects, biodiversity, natural enemies