Larval Instars and Adult Flight Period of Monochamus saltuarius (Coleoptera: Cerambycidae)

Abstract

Monochamus saltuarius is a vector of Bursaphelenchus xylophilus in Japan, South Korea, and the middle temperate zone of China. However, there are only a few reports on this species in China, and its biological characteristics are still unclear. In this study, we aimed to elucidate the larval development and adult flight period of M. saltuarius to provide a theoretical basis for the effective control of pine wilt disease in the middle temperate zone of China. Seven morphological variables of larvae were measured to determine the number of larval instars, and the adult specimens of M. saltuarius were collected from traps in forests to study the flight period of adults in Fushun, Liaoning, the epidemic center of pine wilt disease in the middle temperate zone of China. The results revealed that the full larval period of M. saltuarius was 279.6 d, and the larvae had five instar stages, with an average duration of 7.4, 14.3, 49.8, 83.6, and 124.5 d, respectively. Additionally, 78.4% of the overwintering larvae were fourth instar, and 21.6% were fifth instar larvae. We also found that the adults began to emerge from early May to late June, and the period was from early May to mid-August in the forest. During the investigations period from 2018 to 2020, the total number of adults captured was minimal at 744, and precipitation was highest at 291.54 mm in 2019. We characterized the larval instars and adult flight period of M. saltuarius, which is a prerequisite for developing appropriate management strategies. The results of this study will provide an important reference for the formulation of strategies to control M. saltuarius and pine wilt disease.