Occurrence patterns of Myllocerinus aurolineatus (Coleoptera: Curculionidae) and histological observation of adult female tissues.

Abstract

From March 2023 to December 2024, a comprehensive study was conducted on the field population dynamics, developmental duration, life history, and ovarian development of Myllocerinus aurolineatus (M.aurolineatus). The study combined systematic field surveys, laboratory rearing, and ovarian dissection. The results indicated that M. aurolineatus has one generation year. The temporal dynamics varied slightly between years. In 2023, adult emergence began in early May, with a population increase in late May and a peak density in early June. In 2024, emergence occurred earlier (late April); the population abundance increased in mid-May, reaching maximum abundance by late May. The developmental duration of M. aurolineatus varied markedly, with the larval stage lasting the longest (281.71 d) and the egg stage the shortest (13.49 d). Oviposition peaked between mid-June and early July. Larvae began hatching in mid-June and inhibited the soil until the subsequent April. Pupation occurred in mid-April, marking the onset of adult emergence in late April. The ovarian development process could be divided into 6 grades, from grade I to grade VI. Field sampling revealed that by late May, adults at the oviposition peak grade (grade IV) had already appeared, and subsequently collected adults were all sexually mature. Taken together, the analyses of population dynamics and ovarian development indicate that the optimal time for controlling M. aurolineatus is before late May, when the adult population has reached peak abundance but females have not yet oviposited, thereby providing valuable guidance for its management.