Natural Enemies of the Cedar Processionary Moth, Thaumetopoea bonjeani (Lepidoptera: Notodontidae) in Algeria

The cedar processionary moth, Thaumetopoea bonjeani (Powel) (Lepidoptera: Notodontidae) is one of the damaging defoliators of Atlas cedar forests in North Africa (Démolin 1988; Mouna 2013; Battisti et al. 2015; Rahim et al. 2016; El Mokhefi et al. 2021). Thaumetopoea bonjeani is known to be monophagous on Atlas cedar which is adapted to high elevation/altitude. This species was included in the fauna of Algeria in 1986 (Démolin 1988). The negative impact of cedar processionary moth can be regarded in at least two aspects. Defoliation reduces wood growth and can also lead to drying of the wood (Rahim 2016). Infestations can also be harmful to humans, causing skin lesions (i.e. urticaria or dermatitis), conjunctivitis and respiratory symptoms or even anaphylactic shock (Battisti et al. 2017). Populations of the cedar processionary moth, like many other foliage-feeding forest insects, exhibit periodic gradations or population cycles. For example, in Djurdjura Forest in northern Algeria, heavy defoliation caused cedar tree dieback since 2010 (Rahim 2016). The reasons of the increase in density are unknown, although one can speculate that these relic stands are less buffered against changes of both abiotic (weather) and biotic (natural enemies) factors. The populations of many phytophagous insects are largely determined by their natural enemies (Price et al. 1980; Wallner 1987). For example, parasitoids and predators play an important role in reducing the population density of T. bonjeani in egg batch stages (Rahim et al. 2016). However, little is known of the natural enemies of T. bonjeani at larval and pupal stages, or what role they might play in the regulation of populations. We investigated the natural enemies of T. bonjeani in the Djurdjura National Park (36°39’N 4°01’E), in natural stands of Atlas cedar (age of trees: 20–90 years). The park is 140 km southeast of Algiers, Algeria, approximately 1600 m above sea level and with a sub-humid climate. Collections were made of larvae and pupae of T. bonjeani in 2014 and 2015. All larval instars of T. bonjeani were collected at about. biweekly intervals from April to July in both years, corresponding to the larval development period. The first four larval instars were collected to 1–3 m up a tree trunk, and then taken to the laboratory (at 22 ± 2 °C) where they were reared in clear plastic containers (26.5 × 13.5 × 7.5 cm) and fed Cedrus atlantica needles. The fifth-instar larvae were collected when they began their procession that would result in pupation and placed in containers containing soil, and reared at 30 ± 2 °C. The containers were checked every other day for parasitoid emergence. Thaumetopoea bonjeani pupae were collected during August in both years of the study. The pupae that were collected were placed individually in glass tubes (70 mm × 9 mm diameter) closed with cotton plugs, until parasitoids or adult moth emerged. Dead pupae with the presence of external mycelium were separated for fungal pathogen identification. All insects observed hunting or feeding on larvae and pupae of T. bonjeani during the two years of sampling were collected carefully, and transferred to the laboratory to make sure that each natural enemy fed on one or several biological stages of the pest. The identity of the predators was assessed through observations made during daytime on a total of 16 field visits in April–August 2014 and 2015. Identification and/or confirmation