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Dispersal
kernels of the invasive alien western corn rootworm and the
effectiveness of buffer zones in eradication programmes in Europe L.R.
Carrasco, T.D. Harwood, S. Toepfer, A. MacLeod, N. Levay, J. Kiss,
Baker, J.D. Mumford, J.D. Knight (2010) Annals of Applied Biology |
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AbstractEurope
is attempting to contain or, in some regions, to eradicate the invading
and maize destroying western corn rootworm (WCR). Eradication and
containment measures include crop rotation and insecticide treatments
within different types of buffer zones surrounding new introduction
points. However, quantitative estimates of the relationship between the
probability of adult dispersal and distance from an introduction point
have not been used to determine the width of buffer zones. We address
this by fitting dispersal models of the negative exponential and
negative power law families in logarithmic and non-logarithmic form to
recapture data from nine mark-release-recapture experiments of marked
WCR adults from habitats as typically found in the vicinity of airports
in southern Hungary in 2003 and 2004. After each release of 4000–6300
marked WCR, recaptures were recorded three times using non-baited
yellow sticky traps at 30–305 m from the release point and sex
pheromone-baited transparent sticky traps placed at 500–3500 m. Both
the negative exponential and negative power law models in non-log form
presented the best overall fit to the numbers of recaptured adults (1%
recapture rate). The negative exponential model in log form presented
the best fit to the data in the tail. The models suggested that half of
the dispersing WCR adults travelling along a given bearing will have
travelled between 117 and 425 m and 1% of the adults between 775 and
8250 m after 1 day. An individual-based model of dispersal and
mortality over a generation of WCR adults indicated that 9.7–45.3% of
the adults would escape a focus zone (where maize is only grown once in
3 consecutive years) of 1 km radius and 0.6–21% a safety zone (where
maize is only grown once in 2 consecutive years) of 5 km radius and
consequently current European Commission (EC) measures are inadequate
for the eradication of WCR in Europe. Although buffer zones large
enough to allow eradication would be economically unpalatable, an
increase of the minimum width of the focus zone from 1 to 5 km and the
safety zone from 5 to 50 km would improve the management of local
dispersal. |
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