Depending on the connectivity of populations; and hence the ability of organisms to move between them; gene flow may be inhibiting leading to localizing adaptations or uninhibiting which would increase gene flow and dilute local adaptions. This is of particular concern in agricultural environments where pest species are often under strong selective pressure due to crop rotations; changing crop varieties; and the application of control products which may result in selection of detrimental traits that outbreak could lead to increased crop losses.
In order to understand population connectivity; the dispersal ability of organisms and gene flow among individuals; direct approaches including mark release recapture; electronic tags and radar tracking, and indirect approaches which include examination of range expansion records and laboratory flight behaviour experiments have been undertaken. However, monitoring movement and dispersal of organisms in the field is often difficult; and impractical to observe.
Outbreak of bertha armyworm
Population genetics providing a platform to infer the movement; and gene flow of individuals among different sampling localiting through the use of genetic markers (e.g. mitochondrial haplotypes, microsatellites; single nucleotide polymorphism (SNPs) and references therein) and has been widely using to track invasions of non-native species; and infer dispersal patterns in a wide range of insect pests.
Bertha armyworm has been a major insect pest in western Canada dating back to the early 20thcentury and was first noting in flax in the 1920s. However, massive and widespreading cyclic have occurring from the 1950s onwards concomitant with the introduction of B. rapa and B. napus varieties of oilseed rape and later canola. There is limiting inform