Psyllid ecology and biodiversity in the Pacific Northwest

Abstract

Potato is the fourth-most-valuable commodity in Washington State. The emergence of zebra chip disease (“ZC”) has triggered economic losses in the U.S. Pacific Northwest (“PNW”) with a ca. 7% increment in the total cost of potato production, endangering the economic viability of the region. The vector of the ZC pathogen, Candidatus Liberibacter solanacearum (“Lso”) is the potato psyllid (“PP”), Bactericera cockerelli (Šulc) (Hemiptera: Triozidae). The overall aim of my research was to study the PP ecology on a non-crop host, bittersweet nightshade (Solanum dulcamara L.) (“BN”), and determine presence of Lso. Chapter 1 is an introduction of the importance of ZC. Chapter 2 presents the population dynamics of PPs living BN in Eastern Washington in 2012-2013. A high population and reproduction of PPs was found on BN, higher

than the numbers usually found in potato fields. Molecular analyses found an apparent absence of Lso in these PPs and plants, while revealing that all PP collected were of the Northwestern COI-haplotype. Other agricultural pests were found living on BN. Chapter 3 describes the predator community found (> 40 species), which could be reducing PP. The dominant taxa were Araneae (> 70% of all predators) and predator mites (Anystidae) (> 15% of all predators found). Observations of predator activity revealed PP egg consumption by the tiny coccinellid Stethorus punctillum Weise and attack of PP nymphs by the parasitoid Tamarixia triozae (Burks). Chapter 4 presents a checklist of the Psylloidea superfamily found in the PNW. To know the diversity of psyllid species in this region I compile the published registers and the specimens housed in PNW entomological museums. The list presents 124 species from 25 genera; 35 species are new reports in the PNW. Chapter 5 contains a scientific note about the thrips species found during my sampling of BN patches; I report these species that could have been living on BN or on the surrounded plants. Overall, my results show a complex community of PP, other agricultural pests, and predators living on BN, alongside the apparent absence of the Lso bacterium in PP and BN.