The first report of damage caused by an insect pest (Papilio machaon) on ‘Moshgak’ medicinal herb (Ducrosia anethifolia) in Iran

Background and objectives: Ducrosia anethifolia (commonly known as ‘Moshgak’) is a medicinal plant belonging to the family Apiaceae. It is distributed in the southern regions of Iran, particularly in Fars province. This plant is traditionally used for both culinary and medicinal purposes. Its essential oil has shown significant insecticidal activity against certain date palm pests. Additionally, it possesses antioxidant, antibacterial, anti-inflammatory, and memory-enhancing properties. To date, no reports have documented insect pest activity or damage on this plant. However, during a study in the southern regions of Fars province, extensive larval activity of an insect species was observed on D. anethifolia. This report aims to identify the insect species and examine its biological characteristics.
Methodology: Field studies were conducted in March and April 2021, and continued in the following years, in the natural habitats of D. anethifolia in the Khor region (335 km southeast of Shiraz, Fars province). Larvae were observed feeding extensively on the young leaves, stem tips, and flower buds of the plant. These larvae were collected at different developmental stages and reared in the laboratory until they reached adulthood. The adult insects were then identified.
Results: The adult insect was identified as Papilio machaon Linnaeus (Lepidoptera: Papilionidae). The larvae belonged to the first generation, which became active in Larestan from March onwards. No signs of a second generation were observed during the region’s hot summer. In spring, when the first generation was active, 30–40% of the plants were infested, particularly in the early morning or evening. It is important to note that this plant is naturally distributed in a sparse pattern. The insect was consistently observed on D. anethifolia over multiple years. In certain remote areas where perennial plants with thick roots were present, larval infestations were more frequent. Papilio machaon is widely distributed across North America, Europe, North Africa, and most of Asia. In Iran, it has been reported from nearly all regions, including Fars province (Shiraz and Kazerun). This butterfly can be found from sea level to altitudes above 3,600 meters. Its host plants belong to the families Apiaceae and Rutaceae. The larvae employ camouflage as a defense mechanism: young larvae resemble bird droppings, while older larvae exhibit coloration similar to their host plants. Some subspecies of P. machaon are unpalatable to birds, serving as an additional defensive strategy. The adults feed on nectar. Certain wasp species have been reported as parasitoids of this butterfly, suggesting that future studies should investigate the presence of natural enemies in the region.
Conclusion: The D. anethifolia population in Larestan, Fars province, faces threats due to overharvesting and climate change. Local communities harvest this plant during its vegetative growth phase, preventing many individuals from reaching the flowering stage. In nature, the plant primarily propagates through seeds. Given that P. machaon larvae feed on the immature and unopened flower buds, this insect may negatively impact the reproductive success of D. anethifolia by reducing seed production, ultimately threatening the plant’s natural regeneration and survival.