Egg mortality in the cedar processionary moth, Thaumetopoea bonjeani (Lepidoptera: Notodontidae), in an outbreak area of Algeria

The cedar processionary moth, Thaumetopoea bonjeani (Lepidoptera: Notodontidae), is one of the most serious pests of Cedrus atlantica in north-western Africa (Algeria and Morocco). We report on T. bonjeani egg mortality and the diversity and abundance of parasitoids associated with its eggs in the area of Djurdjura Mountain (Tala-Guilef, Algeria). For this goal, 223 egg batches were collected from C. atlantica over two cohorts (2012 and 2013). The average number of eggs per egg batch increased from 143 in 2012 to 171 in 2013, while the egg mortality decreased from 47.4% and 23.9%, respectively, possibly because of a dilution effect. The most important factors of egg mortality were parasitoids and predators, with hymenopteran egg parasitoids killing from 12.1% to 34.9%, and predators from 5.2% to 7.4% of the eggs. The pattern of egg parasitism was driven largely by Ooencyrtus pityocampae, accounting for about 94% of the total parasitoids, followed by Baryscapus servadeii and Trichogramma embryophagum. An hyperparasitoid Chartocerus sp. was collected for the first time from eggs of Thaumetopoea species. As the two major egg parasitoids are shared with the pine processionary moth Thaumetopoea pityocampa in the same area, it is likely that parasitoid abundance may depend on the occurrence of both hosts.