Abstract: The Yunnan shoot borers, Tomicus species, are indigenous shoot-feeding beetles that attack the Pinus yunnanensis in southern China. To provide a generally concentration on the physiological aspects and feeding divisions, the proventriculus of 4 Tomicus species, including T. yunnanensis, T. minor, T. piniperda and T. brevioplius, were analyzed with scanning electron microscopy. The results showed the adult proventriculus consisted of 8 chitinous plates are in lantern-like shape. Each plate is involved in the anterior plate and masticatory plate. The former has no median suture on the surface plate, which presents many transverse tooth lines with all types of denticles; while the latter is composed of declivity, stopping bristles and mastiutory brush. Together evolutionary relationship of proventricular structure corroborate the cuticular denticles and stopping bristles as well as substitute stopping bristles that play a critical role in feeding divisions among the scolytidae. Particularly, the spine-like hairs occurred on the median suture may indicate the niche difference of coadaptation on Tomicus species. The results will benefit for the further understanding the nutrient utilization and resistance ability of Tomicus species to the host trees.

Key words: Pinus yunnanensis； Tomicus spp., proventriculus, ultrastructure, feeding divisions