Seasonal fluctuation in Candidatus Liberibacter asiaticus prevalence in Florida populations of the Asian citrus psyllid

Candidatus Liberibacter asiaticus (Las) is a bacterial pathogen presumed to cause Huanglongbing disease. Management of the disease is a top priority for the citrus industry because the disease reduces yield, yield quality, and eventually kills the trees. The disease is vectored by the Asian Citrus Psyllid (ACP) (Diaphorina citri Kuawyama). Therefore, one approach to disease management is to manage psyllid populations. However, management costs are high and heavy use of insecticides may select for insecticide resistant vectors. One management strategy to solve this problem would be to target management activities to seasons when the risk of transmission is greatest. To better understand the bacteria-vector interaction we collected in ACP in central Florida for 20 months beginning January 2008. In the first year there were two peaks where Las prevalence in ACP was greatest. A similar pattern is emerging in the second year. While most of our sample sites are in central Florida, we added a new site near Miami. All the trees (orange, grapefruit, and lime) at this location were infected. The seasonal prevalence at this site followed a substantially different seasonal pattern than that in central Florida. We do not know if the different pattern is due to location or Las prevalence in groves.