A clearer
understanding of the mating and dispersal behavior of the Western corn
rootworm, Diabrotica virgifera virgifera (LeConte), is essential to help predict potential resistance
to transgenic corn technologies (B.t. corn) deployed to combat this pest. Field
research was conducted in the summer of 2006 to determine how far newly emerged
female beetles move before mating occurs and the time of day of this initial
mating. Newly-emerged females were examined from the time of emergence for up
to 4 hours or until mating occurred. Preliminary data indicate that female
beetles do not move a significant distance from the site of emergence before
mating. In order to quantify movement of male beetles, complementary studies
were conducted in commercial transgenic cornfields that included the
EPA-mandated 20% refuge acreage.
Wing traps containing a single virgin female beetle were placed in the
transgenic area of the field, at known distances from the nearest refuge and
vice versa. Male beetles were collected from the sticky bottoms of traps and
had their gut contents assayed with protein test strips to determine whether
the B.t. protein was present. This provided an estimate of the distances
traveled by males to reach virgin females. The implications of these data for
movement and mating patterns of adult rootworms in B.t./refuge environments are
discussed.