关键词: 祁连圆柏, 银蛾属, 祁连圆柏双歧姬小蜂, 生物防治

Abstract: Sabina przewalskii is an endemic tree species of the genus Sabina (Cupressaceae) in China, serving as a key constructive species of the alpine ecosystems across the northeastern Qinghai-Tibet Plateau, western Loess Plateau, and the western edge of Sichuan. However, in recent years, cones of S. przewalskii have been severely damaged by seed-feeding pests, with seed infestation rates generally exceeding 80% and leading to near-total seed loss in some stands, thereby significantly impeding both natural regeneration and artificial afforestation efforts. To clarify the pest species and their natural enemies in an effort to develop control strategies, an investigation was conducted from 2024—2025 in Beishan Forest Farm, Huzhu County of Qinghai Province, located in the core areas of the Qilian Mountains. Cones of S. przewalskii were collected from different Sabina forest stands and altitudes and subsequently reared in laboratory. Emerged insects were monitored daily and collected, which allowed the identification of two pest species and four parasitoids. The two cone pest species are larvae of Argyresthia sp. (Lepidoptera: Argyresthiidae) feeding on the outer green fleshy scales, and Megastigmus sabinae (Hymenoptera: Torymidae) damaging the seed kernels. Furthermore, the four species of parasitoids attacking the larvae and pupae of Argyresthia sp. and the torymid wasp were identified. Among the parasitoids, one dominant eulophid species was found with parasitism rate of 88%. By taxonomic study, it was determined as a new species, Dicladocerus qilianshanensis Yang et Liu, sp. nov. (Eulophidae, Hymenoptera), for which morphological description was detailed with color photographs. Meanwhile the comparison of the new species with a close species in the genus Dicladocerus was provided. It is close to Dicladocerus occidentalis Yoshimoto, 1976 in North America, but the new species females are with long body (3.2—4.0mm) (for D. occidentalis, only 3.0mm), gaster length 1.27 times as long as mesosoma (for D. occidentalis, 1.5 times), the branch on funicle 1 of male with length 1.3 times its funicle length (for D. occidentalis, 3 times), the branch on funicle 2 with length 1.7 times its funicle length (for D. occidentalis, the branch reaches to club 1); the male gaster length 0.85 times the mesosoma (D. occidentalis, the gaster is longer than the mesosoma). Additionally, the bionomics of the new parasitoid was briefly summarized too. The discovery of the new species offers promising biological control agents against the two cone pests, particularly the Argyresthia sp. With high parasitism rate and relative female proportion, the natural enemy has a promising potential for use in biological control and will play a crucial role in managing the cone pests, thereby contributing substantially to the conservation of the germplasm resources of this valuable tree species.

Key words: Sabina przewalskii, Argyresthia sp., Dicladocerus qilianshanensis Yang et Liu, biological control