Genetic structure of the lucerne flea, Sminthurus viridis.

The lucerne flea, Sminthurus viridis, is a major agricultural pest of pasture legumes and broadacre throughout southern Australia and New Zealand. As current control methods for this pest are heavily reliant on pesticide use, there is a need for the development of an integrated pest management (IPM) strategy. However, this requires a greater understanding of lucerne flea biology and ecology than that currently available in the literature. This study aims to rectify this problem by examining the population biology and life-cycle of the lucerne flea, as well as investigating chemical and biological control methods. Genetic markers are being used to examine the population structure, migration potential and mode of reproduction. Allozyme markers have been already used to show that Victorian lucerne flea populations reproduce sexually and have significant structure due to limited gene flow. Microsatellite markers are being developed to obtain greater resolution for these important aspects of population biology. Pesticide testing so far has found the lucerne flea to be substantially more tolerant of several registered chemicals when compared to the red-legged earth mite. Longitudinal sampling of several populations suggests at least two generations occur during a season with numbers peaking in autumn and spring. In additions, field experiments investigating the process of summer aestivation in the lucerne flea are to be carried out in 2007 and 2008. The findings from these experiments will have potential importance for timing lucerne flea control strategies.