Do Locusts seek greener pastures? John Weiss, Mick McCarthy, Kim Lowell & Simon McKirdy CRC NPB, Vic DPI & CEED (UoM)
PhD candidate
biosecurity built on science Cooperative Research Centre for National Plant Biosecurity
Visual Host Selection Vic DPI Biosecurity SA DAFF – APLC “must not be green-coloured, as locusts are attracted to green areas.” GRDC “The locusts seem to be attracted to any green bridge of volunteer cereals and paddocks of grass” biosecurity built on science
Host Selection
biosecurity built on science
Adult APL abundance vs “greenness�
biosecurity built on science
Aust. Plague Locusts in Victoria 2010-2011
Egg beds and hoppers to Oct 2010
Survey locations and sites – Dec 2010 – April 2011
biosecurity built on science
Adult APL abundance vs “greenness”
2 generations – weekly surveys for 4 months 2000+ transects, 152 sites, 19 localities
biosecurity built on science
1st generation
Adult APL abundance vs “greenness”
gC/m2/day
2 generations – weekly surveys for 4 months 2000+ transects, 152 sites, 19 localities
biosecurity built on science
Bayesian Hierarchal modelling APL[i] ~ dpois(m)
2nd generation
log(APL) = b1 + b2*sGPP+ b3*sGPP2 + reDay + reSite + reLocation + reluse + re
gC/m2/day biosecurity built on science
Bayesian Hierarchal modelling APL[i] ~ dpois(m)
2nd generation
log(APL) = b1 + b2*sGPP+ b3*sGPP2 + reDay + reSite + reLocation + reluse
gC/m2/day biosecurity built on science
Bayesian Hierarchal modelling APL[i] ~ dpois(m)
2nd generation
log(APL) = b1 + b2*sGPP+ b3*sGPP2
gC/m2/day biosecurity built on science
95% Creditable intervals 2
log(APL) = b1 + b2*sGPP + b3*sGPP + reDay + reLocation + reluse + reSite 3
2
1
0
-1
biosecurity built on science
Comparison Modelled vs Actual b1 + b2*sGPP+ b3*sGPP2 + reDay + reSite + reLocation + reluse
Ln (Actual)
b1 + reDay + reSite + reLocation + reluse
b1 + b2*sGPP+ b3*sGPP2
Ln (Model prediction) 2 r =0.772
r2=0.766 r2=0.001 biosecurity built on science
Summary Most important variables Location Site Less important Day Least important VI (FPAR, GPP, NDVI) Landuse (subcomponents of grasslands) biosecurity built on science
Summary
Do locusts seek greener pastures? No evidence to suggest they did in Vic in 2010-2011 Strong spatial autocorrelation (2 scales - site and location) Limit to spatial/ temporal resolution of Veg indices. Possible threshold level reached
biosecurity built on science
Summary
Do locusts seek greener pastures? No evidence to suggest they did in Vic in 2010-2011 Strong spatial autocorrelation (2 scales - site and location) Limit to spatial/ temporal resolution of Veg indices. Possible threshold level reached
biosecurity built on science
Aust. Plague Locust Commission 10yrs data 2001-2010
Eg 2007-08 4000 APL presence 10000 absence
Thank you  For more information, please email John.Weiss@dpi.vic.gov.au biosecurity built on science