The date palm scale (DPS) Parlatoria blanchardi is a serious pest due to the damage it inflicts on its host tree (Phoenix dactylifera). To develop an effective control against DPS in arid regions, it is essential to know its bio-ecology including population dynamics and climatic factors influencing the duration and timing of life history and also the densities of different phenological stages (crawlers, first and second instars nymphs, adult males, and adult females). Monitoring of biological cycle and population dynamics of the pest were achieved through weekly counts of DPS densities on leaflets sampled at different position of date palm trees in an oasis of Ouargla region (Algerian Sahara Desert). Within this hyper-arid region, DPS established four generations per year, the most important was the spring generation. Two overlapping generations occurred in spring-early summer and two in autumn-early winter; these two pairs of generations were interspersed by two phases of high-mortality rates, the first corresponds to winter cold and the second refers to the extreme heat of summer. Statistical analysis of the effects of the studied climatic conditions (minimum, maximum and mean temperatures, precipitation, humidity, wind, rain days, and climatic indices) on the DPS densities at different phenological stages showed great variability from one stage to another. Among these, adult females were the most affected by climate factors. For the total DPS population, high values of minimum temperatures negatively affected population density, while high maximum temperatures, hygrometry, and De Martonne aridity index showed a positive influence.

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.Abstract --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. Résumé --Introduction. L'acarien Oligonychus afrasiaticus, localement appelé « Boufaroua », est un ravageur des palmeraies algériennes. Pour se nourrir, il pique les dattes qui se dessèchent ensuite en fin de maturité et deviennent impropres à la commercialisation et à la consommation humaine. Des pertes économiques importantes sont alors enregistrées. Les dégâts les plus spectaculaires ont été notés sur la variété Deglet-Nour à haute valeur marchande. Matériel et méthodes. Le taux d'infestation des arbres d'une palmeraie de la région d'Ouargla a été évalué. Quatre stades phénologiques ont été considérés. Une coccinelle très vorace, Stethorus punctillum, a été récoltée dans six palmeraies puis lâchée sur des arbres expérimentaux afin de vérifier son efficacité prédatrice sur le « Boufaroua ». Résultats. L'infestation des arbres a été très variable et a augmenté au fur et à mesure de la maturité des dattes. L'efficacité de la coccinelle lâchée a été significative, et cela a été d'autant plus constaté que les arbres étaient fortement infestés. Discussion et conclusion. Stethorus punctillum joue un rôle important dans le contrôle de l'acarien O. afrasiaticus. D'autres prédateurs seraient toutefois présents en Algérie ; ils devront être testés afin d'établir une méthode de lutte biologique apte à protéger suffisamment les palmeraies contre O. afrasiaticus.Algérie / Phoenix dactylifera / fruits / stade de développement végétal / ravageur des plantes / Oligonychus afrasiaticus / lutte antiacarien / agent de lutte biologique / préda...

Taux d'infestation et morphologie de la pyrale des dattes Ectomyelois ceratoniae (Zeller) sur diffé rentes varié té s du palmier dattier Phoenix dactylifera (L.

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