Characteristics of date fruit and its influence on population dynamics of Oligonychus afrasiaticus McGregor (Acari: Tetranychidae) in the southern Tunisia

摘要

Oligonychus afrasiaticus, the old world date mite, is a serious pest of dates in Tunisia. The infestation of O. afrasiaticus begins and increased during the Kimri stage, characterised by the green colour of fruit. The aim of this study is to compare the susceptibility of three cultivars of date palm (Phoenix dactylifera) from Tunisia: Deglet Noor, Alig and Bessr, at different ripening periods, to feeding by O. afrasiaticus. The Deglet Noor cultivar was the most susceptible to O. afrasiaticus. The largest population of O. afrasiaticus on Deglet Noor, Alig and Bessr were recorded when the water content reached 83 %. Highest acid activity >2 mEq/100g, prevented mite establishment on the tree cultivars. Later in the season, when total sugar levels reached >420 mg/g fresh fruit, total soluble solids increased above 10% and fruit moisture decreased to < 80 %, mite populations declined. Total phenolics and hardness of the exocarp were not key factors in mite establishment.