Larvae of grassland caterpillar endemic to Qinghai–Tibet Plateau (Lepidoptera: Lymantriinae: Gynaephora): identification, distribution, and ultramorphology

Abstract The grassland caterpillar is a significant pest of alpine meadows in the Qinghai-Tibet Plateau. Its larvae primarily feed on forage grasses, resulting in financial losses. However, little research has been done on the morphological features of larvae of this species thus far. The distribution and habitat of Gynaephora menyuanensis were extensively investigated in this instance through field study. Using an optical and scanning electron microscope(SEM), the external morphology and ultramorphology of the last instar larvaeof G. menyuanensiswere investigated. The findings indicate that this species is primarily found in the northeast of Qinghai Province in alpine meadows at an altitude of 3,000–3,500 m. For the first time, SEM is used to report more comprehensive morphological structuresof G. menyuanensis, including larval head capsule, mouthparts, antenna, sensilla, thoracic legs, prolegs, and setae. The larvae have two distinct color funnel warts (yellow and red) on abdominal segments VI and VII, which sets them apart from other lepidopterous larvae. Additionally, the chaetotaxy of first instar larvae of G. menyuanensis were studied and described in detail, identifying seven clusters(PD, D, SD, L, SV, V, CV) on the larval trunk. This study offers a theoretical basis for phylogenetic analysis, the adaption evolution of G. menyuanensis, and a systematic discussion of the application of morphological features of larvae to classification.