Insect laccase-1 is involved in immune defense and detoxification.The differences in the ability of the invasive whitefly,Bemisia tabaci Middle East-Asia Minor 1(Gennadius)and Trialeurodes vaporariorum(Westwood)(both Hemiptera: Aleyrodidae)to utilize laccase-1 were explored.Laccase-1 was found in the watery saliva of both B.tabaci MEAM1 and T.vaporariorum,and its activity in T.vaporariorum was higher.Gene transcript analysis revealed that laccase-1 could be expressed at every developmental stage in both species.The highest expression level in B.tabaci MEAM1 was observed at the adult stage,but no significant difference was observed in T.vaporariorum.Expression levels in adult B.tabaci MEAM1 were higher than T.vaporariorum.The transcriptional level of laccase-1 in the midgut was higher than those in cephalothorax and abdominal tissues in both species.After feeding on tomato plants sprayed with salicylic acid solutions,the expression level of laccase-1 in B.tabaci MEAM1 decreased,but T.vaporariorum was not significantly affected.The present result indicated that the laccase-1 may be important in the host defense response and in the competition between B.tabaci MEAM1 and T.vaporariorum.