The Australian plague locust (APL), Chortoicetes terminifera (Walker), is a native but serious pest in Australia. In order to control locust plagues, managers need to know not only what areas are at risk as the adults disperse but where the highest densities of locusts are. Foraging theory indicates that areas with greener grass (more digestible, with higher protein, carbohydrate and water content) should be where adult locusts would preferentially feed. Anecdotal evidence from farmers and the Australian Plague Locust Commission also supports this, however there is no published field research on this area. This work aimed to investigate the relationship between APL abundance and greenness as derived from satellite remote sensing vegetation indices.
In 2010-2011, Victoria suffered from its largest locust plague since 1976. Over a four month period from December to April 2011, 150 sites in 19 localities across central Victoria were monitored weekly and adult APL densities recorded. MODIS satellite Vegetation indices (FPAR, GPP and NDVI) were utilised as an indication of grassland and cereal crop’s “greenness”.
Bayesian hierarchal analysis was utilised to model densities of APL at different sites, localities, type of grassland use, time periods and determine the level of correlation to the Vegetation indices.
No evidence was found for increased locust abundance at greener sites. The most important variables were site and location which indicate two scales of spatial autocorrelation or clustering. The least important variables in determining abundance were any of the Vegetation indices and grassland landuse.
Possible confounding factors are the spatial and temporal resolution of the satellite data and the unusually wet summer contributing to much higher levels of greenness found throughout the study area.