What are the main species of coniferous longicorn beetles? What are the characteristics of Monochamus alternatus?

In China, there are many kinds of longicorn beetles that harm conifers. Common species are Monochamus alternatus, Monochamus alternatus, Monochamus alternatus, Monochamus alternatus, Monochamus alternatus and so on. Except for a few species, most of them infringe on weak trees and cut down trees, and hinder the growth of trees after other disasters (such as leaf-eating pests, floods and droughts, etc.). ). Because larvae drill large passages in xylem, it will seriously damage materials and cause huge economic losses.

Among them, Monochamus alternatus 1 year 1 replaced mature larvae to overwinter in xylem pores. In late March of the following year, the overwintering larvae began to pupate in the pupa room at the end of the wormway. Adults emerged in mid-April, and the peak of adult activity was in May. Adult activities can be divided into three stages, namely, moving and dispersing stage, supplementing nutrition stage and spawning stage. At first, it was mainly on the trunk and twigs of 1 ~ 2 years old, and then it gradually moved to perennial branches to feed. Adults like biennial branches. Adults hardly move in the late stage of nutritional supplement. Before laying eggs, they bite grooves in the trunk, and then put the ovipositor tube into the bark to lay eggs. Mating and spawning take place at night. Each female lays about 200 eggs100 in her lifetime. Weak wood and newly cut wood can attract adults to lay eggs.

Larvae * * * 5th instar, 1 instar larvae feed on the endothelium, and 2nd instar larvae feed on the surface of sapwood, forming irregular flat pits on the endothelium and sapwood, which leads to the destruction of the tree transportation system. Larvae burrow into xylem for about 3 ~ 4 years. In autumn, after 3 ~ 4 cm deep into xylem, longitudinal pits are dug up or down, about 5 ~ 10 cm long, and then bent outward to eat sapwood. A pupa chamber is built at the bottom of the pit to pupate, and the whole tunnel is U-shaped. Except for a little debris left near the pupa chamber, most of the larvae were pushed out under the accumulated bark.

Adults like light, and the optimum temperature is about 20℃, which generally occurs more seriously in sparse stands. In the stand with high canopy density, the edge trees suffer the most, or the open space in the forest occurs first and then spreads around. If the cut trees are transported out of the forest in time, stay in the forest for the summer, or are not peeled, they will soon be invaded by this insect, and the migration distance of adults is 1.0 ~ 2.4 km.