Evaluation of Flea Beetle (Phyllotreta spp.) Resistance in Spring and Winter-type Canola (Brassica napus).
This thesis is an investigation into the understanding of flea beetle (Phyllotreta spp.) resistance in spring-type and winter-type canola quality Brassica napus L.. Canola is one of the world’s most widely grown oilseed crops and an economically important crop in Western Canada. Genetic resistance to this common pest would add to the available tactics for integrated pest management of flea beetles in canola. The purpose of this research was to better understand the interactions of the flea beetle with canola at key feeding times in the life cycle of the flea beetle and identify genetic components related to flea beetle herbivory on canola seedlings. The objectives were to: 1) investigate seasonal effects of flea beetle herbivory on both spring-type and winter-type canola; and 2) identify quantitative trait loci (QTL) for flea beetle herbivory in two winter-type doubled haploid (DH) populations using simple sequence repeat (SSR) markers and single nucleotide polymorphic (SNP) markers. Year and seasonal effects were noted but overall trends amongst entries were similar concluding that flea beetle feeding patterns did not change throughout its life cycle. Spring-type and winter-type germplasm reacted similarly under flea beetle feeding. As such, there does not appear to be any novel resistance mechanisms that evolved as a result of divergent growth habit types in canola. Seven QTL were identified over the iii two DH populations studied. Linkage group (LG) N13 had multiple QTL identified. The remaining QTL were located on LG N04, N06, N15 and N17. It is unknown as to what mechanisms these QTL are associated with. The results of this thesis provide insight into flea beetle-canola plant interactions and identify some genetic areas of interest related to flea beetle herbivory in canola.