## 1 Introduction  
The longhorn beetle _Monochamus alternatus_ (coleoptera: Cerambycidae) is an important stem-boring pest of conifer. The adults gnaw on bark, causing host decay. Larvae bore the harm of decay, damage the xylem and phloem of trees, seriously affect the growth of pine trees, and even lead to the death of pine trees. It is also the main vector in Asia of the invasive pine wood nematode (PWN), _Bursaphelenchus xylophilus_ (Steiner et Buhrer) Nickle (nematoda: Aphelenchoididae) [1, 2]. Originating from North America, _B. xylophilus_ causes a devastating pine disease [3, 4]. Since the first outbreak of pine wood nematode disease (PWD) in 1914 on Japan's Honshu Island, the disease has been found in East Asia (Japan, Korea and China) and Europe (Portugal) [5]. It has now become a worldwide threat to forest ecology and international trade [4]. _B. xylophilus_ has a very short life history and can reproduce rapidly in the host. After the eggs hatch into larvae, they develop into adults in different instars (J2-J4) within a week. _B. xylophilus_ has strong fertility, with each female laying 90-100 eggs on average during the breeding period, and the parasitic nematodes in each infected tree can reach into the millions [6]. A large number of disease-related enzymes, including cellulase and pectinolytic enzyme, are secreted in the host body of _B. xylophilus_, which mainly cause cell-wall decomposition, and promote the infiltration and migration of pine wood nematode between host cells [7; 8; 9; 10]. _B. xylophilus_ also causes xylem and tracheid dysfunction, hindrances nutrient exchange and water transport, and ultimately causes tree death [11]. Pine wilt disease causes needles to lose water, turn green, red, and yellow, and eventually die; the disease is known as the \"cancer\" of pines. In China, hundreds of millions of pines have been infected since 1982, when it was discovered in the black pine forest at the Sun Yat-sen Mountain in Nanjing. PWD in Asian pines presents typical pathogene-dominant disease characteristics; that is, the prevalence of the disease does not depend on the growth state of the pines, but on whether _B. xylophilus_ can spread to the region to infect the pines. If a pine tree is infected with pine wood nematode disease, it will die no matter how healthy it is. In the process of diffusion and infection of _B. xylophilus_, _M. alternatus_ in Asia as well as other _Monochamus_ spp. in other parts of the world play a key role in carrying, spreading, and assisting the pathogen to invade the host [12]. _B. xylophilus_ cannot complete the infection cycle on its own and needs to be spread via vector insects, which allow it to enter pine trees through wounds caused by _M. alternatus_ feeding or spawning. As an important vector insect of _B. xylophilus_, the control of _M. alternatus_ has always been targeted as a possible method of preventing and controlling PWD [13]. The longhorn beetle is a kind of insect with a perfect self-protection mechanism. Longhorn beetle larvae grow and develop in tree trunks, are not affected by climate, and have little contact with natural enemies, so the population development is stable. Especially, the adult body wall and elytra are thick and have a strong drug resistance. There are few natural enemies and sufficient food resources. General conventional control methods not only cause serious harm to the forest ecological environment, but also have poor control effects. Since the adults are exposed at emergence, the control at the adult stage may represent a suitable control period. Compared with the cryptic larval stage, the insect traps targeting adults, based on the chemical ecology of _M. alternatus_, have been widely used in the monitoring, prevention, and control of forest pests as an environmentally friendly control method. At present, this method has become an important part of the integrated control system of _M. alternatus_[14]. There have been many reports of the successful use of traps to monitor and control pests in the wild.