نوسانات فصلی جمعیت کفشدوزک نقاب‌دار دولکه‌ای Chilocorus bipustulatus L. شکارگر سپردار سفید خرما Parlatoria blanchardi (Targioni Tozzetti) در شهرستان بم

Dates are an economically valuable crop in the southern regions of Iran. Pests such as the palm weevil, date palm rhinoceros beetle, date palm leafhopper, spider mites, and scale insects cause significant damage to this crop. The date palm scale Parlatoria blanchardi (Targioni Tozzetti) is one of the key pests of date palms in Iran, causing substantial damage to orchards, especially young trees. Coccinellids, belonging to the order Coleoptera, are among the largest groups of predatory insects. The heather coccinellid C. bipustulatus L., belonging to the family Coccinellidae, is one of the most important predators of scale insects. This omnivorous insect is widely distributed across Europe, the region, West Asia, and North Africa. It effectively preys on the date palm scale and also feeds on aphids, other scale insects, and mealybugs from the families Eriococcidae, Coccidae, Asterolecaniidae, and Pseudococcidae. Due to its wide distribution, this coccinellid has been considered for mass release in biological control programs. Considering the export of dates and issues such as pesticide residues and the need to replace chemical control methods with safe and sustainable approaches, this study aimed to investigate the population dynamics of the predominant and effective predator of the date palm white scale. For sampling conducted during 2021 and 2022, three groves were selected, and four trees were chosen from each grove. Bi-weekly sampling was performed on each tree. Observations were made on the two lower rows of palm leaves by direct inspection and by shaking the leaves over a white cloth measuring 2 x 5 square meters. The number of ladybugs was recorded during each sampling session. The results showed that the population growth trend of the coccinellid coincided with the population increase of the date palm white scale, with three population peaks observed in May, September, and December. Previous studies indicated that this ladybird is not observed in the orchards during the summer, whereas recent findings show that, although its population is not substantial, it is actively present in the orchards during the summer months. Additionally, the observations in January 2021 and 2022 showed that when daily temperatures ranged between -1 to 11 °C, the coccinellid was seen feeding on the date palm white scale. The population fluctuations of the coccinellid are not influenced by photoperiod, and the population density decrease in summer and winter is related to temperature. The findings of this study contribute to a better understanding of predator-prey interactions and consequently aid in the development of sustainable pest management methods that are environmentally compatible.