Understanding how populations and management tools interact for pest surveillance and eradication

Abstract

Eradicating insect populations is expensive and time-consuming. A better understanding offactors affecting surveillance and response options should improve prospects for eradication success. This thesis brings four linked components together by understanding the processes that interfere with a low-density population's growth rate and how population models and their validation trials can predict the effects of tools used for detection and eradication.The effects of spatial separation and predation on mating success for low- and high-density populations of flies was tested with 3D printed mazes of increasing complexity. Spatial separation and predation negatively affected the probability of mating for low-density, but not high-density fly populations.Population growth models predicted the effects of eradication tools on the intrinsic rate of increase for populations of Bactrocera tryoni, the Queensland fruit fly. The effective sampling area (ESA) of tools estimated the probability of individuals interacting with the tools.Extinction was predicted for populations exposed to some of the tools examined.The effect of combining odours into one trap to optimise fruit fly surveillance was investigated.Antagonistic effects were observed. Fly species trap interaction probabilities were assessed by predicting changes to the relative ESAs of the traps. Up to a 3-fold increase in trap density was estimated to mitigate any reduction of multiple-lure surveillance efficacy when compared to a single lure system.The odour-based eradication tools expected to result in the extinction of B. tryoni populations from in the population models were those that targeted individuals prior to mating. This hypothesis was tested on field populations. The assessment methods used did not allow this hypothesis to be either refuted or validated.Understanding how individuals interact with management tools can help inform the probability that individuals will be detected with surveillance tools and how eradication tools will interfere with population growth. Eradication can be achieved with tools that either reduce population density or require that the pest population density needs to be greater than the prior minimum population density before eradication tool use. Allee effects should improve successful eradication outcomes.