Tomato psyllids: Molecular identification of populations, migrations, and a test of the rigor hypothesis of invasive species

John T. Trumble and D. Liu, Department of Entomology, University of California, Riverside CA 92521, USA

Although tomato psyllid, Bactericera cockerelli (Sulc.) (Homoptera, Psyllidae), annually causes significant losses in potato and tomato crops in Eastern Mexico and the Central United States, infestations in Western North America have been historically rare. However, substantial populations appeared in 2001 in Western North America and caused losses in tomato production exceeding 50% since 2002. To determine if these new outbreaks were the result of a simple range expansion or the evolution of a new B. cockerelli biotype, inter simple sequence repeat markers, as well as COI , ITS2, and wsp sequence data were used to characterize populations of the psyllid. The documentation of genetic differences between the native and invasive populations provided a unique opportunity to test the rigour hypothesis of insect invasions. This hypothesis states that invasive species are more robust than populations form the native range. The results from classical measures of fitness (growth rate, fecundity, size, survival) did not support the rigour hypothesis, but the invasive psyllids did demonstrate other advantages that promoted expansion into Western North America.