_____ is caused by the pine wood nematode and transmitted by several species of longhorned beetles.

Pine wilt is a serious disease affecting pine trees, primarily caused by the pine wood nematode, Bursaphelenchus xylophilus. This nematode is typically transmitted to healthy trees by longhorned beetles that carry the nematode within their bodies. As these beetles infest the pine trees, they create entry points for the nematodes to infect the tree, leading to the rapid decline in health and eventual death of the host.

The nematode disrupts the tree's water transport system by feeding on the cells, leading to wilting of the needles and the tree's overall decline. This disease is particularly destructive because it can spread quickly with the movement of the beetles, and it greatly impacts forests where susceptible pine species are prevalent.

The other options, such as cedar wilt and chestnut blight, refer to different issues affecting other species of trees and are not related to the pine wood nematode or the longhorned beetles. Pine crimsonification does not accurately describe a recognized disease caused by these organisms, thus reinforcing why pine wilt is the correct choice in this context.