Abstract: Wheat is the world′s largest food crop, and about 40% of the world′s population consumes wheat as their daily food.As an indispensable energy source in human daily life, wheat is extremely vulnerable to stored grain pests during storage due to its rich nutrients and other characteristics.Tribolium castaneum(Herbst)is an important grain storage pest in the world, and it often occurs in grain processing and storage places such as wheat flour and rice.In the process of grain storage, it often secretes harmful metabolites, which discolors the grain, causes changes in the composition and content of volatiles in the environment, produces peculiar smell, reduces the quality of food, and causes huge economic losses.Therefore, how to minimize the damage of stored grain pests, reduce the post-harvest loss of grain, and ensure the safe storage of grain is an urgent problem that needs to be solved in the current world food security.In view of this, headspace solid-phase microextraction(SPME)and gas chromatography-mass spectrometry(GC-MS)were used to investigate the changes in the types, components, and contents of volatile substances in the grain storage environment damaged by T. castaneum with different times in this work.The changes of types, contents, and components of volatile substances from wheat infested by the initial population densities of 0, 6, 12 and 18 T. castaneum adults/kg were investigated, respectively.The results showed that the volatile substances of wheat infested by T. castaneum were hydrocarbons, alcohols, aldehydes, acids, esters, and other substances.Ketones appeared in wheat after 20 days of infestation.With the prolonging infestation time, the total contents of volatile substances from wheat increased, and the hydrocarbons gradually decreased first and then increased with increasing population density, while the acid substances first increased and then decreased, alcohol and ester substances decreased, ketone substances increased slightly, but the change was not obvious.The characteristic volatile substances of wheat infested by different initial densities of T. castaneum adults were isopropyl palmitate, 2-n-pentyl furan, longifolene and phenylacetaldehyde, N-decalactone, 2, 5, 5-trimethyl-heptane and n-hexanal.The research result provides a theoretical basis for predicting the occurrence of stored grain pests by detecting the changes of volatile substances in the stored grain environment.This study also lays a foundation for the future research on the tendency selection behavior of the adults of T. castaneum on the volatile constituents of wheat flour.