Factors determining vector competence of the thrips Frankliniella occidentalis for transmitting TSWV Tospovirus

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The epidemiology of the economically important Tomato Spotted Wild Virus (TSWV) is determined by the vector competence of thrips species such as Frankliniella occidentalis. The main aim of the study is to determine factors responsible for the high variability in vector competence of F. occidentalis individuals and populations. The study will be divided in three parts: (1) Investigation of the heritability of the trait vector competence of F. occidentalis for transmitting the TSWV tospovirus on sweet pepper (Capsicum annum) as a model crop. This part consists of crossings with individually characterized vector competent and non-competent females and males of F. occidentalis (single pair crossing). Crossing schemes include back-crossings (F1 -- F2). Frequency of competent individuals (phenotype) will be determined in a biotest, moreover competent vs non-competent individuals should be characterized by genetic markers such as microsatellites and/ or AFLPs to determine allele frequencies on the genome level (genotype) in addition. (2) Determination of the dynamics (over generations) of vector competence (percentage of competent individuals) in differently structured populations over multiple generations in isolated populations of different sizes, of different initial proportions of competent and non-competent individuals and after artificial fragmentation of populations (gene drift and bottle-neck effects). (3) The third part will focus on selected non-genetic factors assumed to additionally influence vector competence or allele shifts in isolated populations. Parameters to be evaluated from individuals characterized as either competent or non-competent will be mating preferences, host plant selection, feeding behavior and mobility (host plant switch) as well as fitness parameters such as longevity and fecundity.