Research Progress on Aggregation Pheromone Systems of Major Ips/Pseudips Bark Beetles Attacking the Thickleaf Spruce: A Mini-Review Extraction and identification of aggregation pheromone components of Scolytus schevyrewi Semenov(Coleoptera: Scolytidae) and trapping test Olfactory Reception of Conspecific Aggregation Pheromone and Host Volatile Terpenes by Asian Larch Bark Beetle, Ips subelongatus