The lucerne flea, Sminthurus viridis,
is a major agricultural pest of pasture legumes and broad acre crops throughout
southern Australia.
As current control methods for this pest rely heavily on pesticides, there is a
need for the development of an integrated pest management (IPM) strategy.
However, this requires a greater understanding of the biology and ecology of
the lucerne flea. This study aims to examine the population biology and
life-cycle of this pest, 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
shown that Victorian lucerne flea populations reproduce sexually and have
significant population structure due to limited gene flow. Microsatellite
markers are been developed to obtain greater resolution of the genetic
structure of populations and determine what limits gene flow between
populations. Pesticide assays have been conducted on a number of chemicals
commonly used for the control of the lucerne flea. These assays have shown that
the lucerne flea is substantially more tolerant of these chemicals when
compared to the redlegged earth mite, H. destructor. This is an
important finding and helps to explain the difficulty in controlling this pest
in the field as application rates of pesticides are generally the same for both
pests. Longitudinal sampling of several populations suggests at least two
generations occur during a season with numbers peaking in autumn and spring.
Field trials investigating the process of summer aestivation in the lucerne
flea are being carried out to provide a complete picture of the lifecycle of
this pest.