Volatile Component Analysis of Michelia alba Leaves and Their Effect on Fumigation Activity and Worker Behavior of Solenopsis invicta

Volatile compounds from mashed (fresh, fallen, and dried) leaves ofMichelia alba were collected via solid-phase microextraction and werethen identified via gas chromatography-mass spectrometry. The resultsshowed that linalool was the dominant component in different leaves,together with caryophyllene, β-elemene, and selinene, the contents ofwhich vary across the samples. The fumigation bioassay results showedthat the volatiles from M. alba leaves exhibited insecticidal activity againstred imported fire ant workers, and the mortality of workers could reachup to 100% after the fallen leaves were treated for 16 h. Mashed freshleaves could effectively reduce the aggregation and drinking ability ofworkers. The volatile substances released from the mashed leaves mightkill the ants, or affect their behavior and weaken the activity by interferingtransmit information between ants. A comprehensive consideration ofthe economic and ecological value of M. alba shows that fallen leavesmight be a good resource to control red imported fire ant