Spatially Explicit Changes in Potato Psyllid (Hemiptera: Triozidae) Populations in Three South Texas Potato Fields

Biology, Ecology, and Management of the Potato Psyllid, Bactericera cockerelli (Hemiptera: Triozidae), and Zebra Chip Disease in Potato

The potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae), transmits the pathogen "Candidatus liberibacter solanacearum" (Lso), the putative causal agent of zebra chip disease (ZC). ZC is a disease of potato that reduces yield and quality and has disrupted integrated pest management programs in parts of the Americas and New Zealand. Advances in our understanding of the ecological factors that influence ZC epidemiology have been accelerated by the relatively recent identification of Lso and motivated by the steady increase in ZC distribution and the potential for devastating economic losses on a global scale. Management of ZC remains heavily reliant upon insecticides, which is not sustainable from the standpoint of insecticide resistance, nontarget effects on natural enemies, and regulations that may limit such tools. This review synthesizes the literature on potato psyllids and ZC, outlining recent progress, identifying knowledge gaps, and proposing avenues for further research on this important pathosystem of potatoes.

A computational study of density-dependent individual movement and the formation of population clusters in two-dimensional spatial domains

The patterns of collective behaviour in a population emerging from individual animal movement have long been of interest to ecologists, as has the emergence of heterogeneous patterns among a population. In this paper we will consider these phenomena by using an individual-based modelling approach to simulate a population whose individuals undergo density-dependent movement in 2D spatial domains. We first show that the introduction of density-dependent movement in the form of two parameters, a perception radius and a probability of directed movement, leads to the formation of clusters. We then show that the properties of the clusters and their stability over time are different between populations of Brownian and non-Brownian walkers and are also dependent on the choice of parameters. Finally, we consider the effect of the probability of directed movement on the temporal stability of clusters and show that while clusters formed by Brownian and non-Brownian walkers may have similar properties with certain parameter sets, the spatio-temporal dynamics remain different.