Effectiveness of the ladybird Stethorus punctillum (Weise) as a predator of the mite Oligonychus afrasiaticus (McGregor) in the palm plantations of the area of Wargla in Algeria.

摘要

Introduction. The mite Oligonychus afrasiaticus, locally called "Boufaroua", is a pest of the Algerian palm plantations. To feed itself, it pricks the dates, which become progressively dry at the end of the maturity and become unsuitable for marketing and human consumption. Significant economic losses are then recorded. The most spectacular damage was noted on the Deglet-Nour date variety, with high commercial value. Materials and methods. The rate of infestation of palm tree plantations of the Wargla area was evaluated. Four growing stages of the plant were considered. A very voracious ladybird, Stethorus punctillum, was collected in six palm plantations, then was released on experimental trees in order to check its predatory effectiveness against the mites. Results. The tree infestation was very variable according to the tree and increased progressively according to date ripening. The effectiveness of the released ladybird was significant, especially when trees were highly infested. Discussion and conclusion. Stethorus punctillum plays an important role in the control of the mite O. afrasiaticus. Other predators, however, are present in Algeria; they will have to be tested in order to establish a method of biological control suited to sufficiently protecting the palm plantations against O. afrasiaticus.