Oral Presentation Science Protecting Plant Health 2017

What can we realistically expect from biocontrol of insect vectors of plant pathogens: is significant disease mitigation possible? (4557)

Mark S Hoddle 1
  1. Department of Entomology, University of California, Riverside, CA 92521, USA

Insects that vector pathogens that cause plant disease present a challenging problem to pest managers. In many cases, low densities of infected vectors can contribute to significant disease outbreaks, which in the absence of pathogen transmission, these pest densities may be tolerable. A dominant management tool for vector suppression are applications of pesticides which may be suitable for use in some agricultural, horticultural, and ornamental commodities grown in protected culture or outdoors. The broad spectrum nature of many insecticides enables them to kill, often rapidly, a suite of disease vectors (e.g., thrips, whiteflies, aphids, and psyllids) which may help mitigate disease spread because of reduced vector densities. However, issues of environmental contaminant, human health and safety concerns, non-target impacts, and resistance development are well documented problems associated with pesticide use. Additionally, in some cases, such as vector management in urban or wilderness areas, insecticides may not be a viable control option for pest control. Under these conditions, biological control, that is the use of host specific natural enemies that attack some life stage (e.g., eggs or nymphs) of the vector, may be the best, and possibly the only control option available for reducing vector densities to less damaging levels. This presentation will review the challenges and benefits of using biocontrol as a management tool for suppressing populations of insects that vector plant pathogens. The primary focus will be on two biological control programs targeting two hemipteran insect vectors. The first review will summarize the effects of classical biocontrol targeting the glassy-winged sharpshooter, Homalodisca vitripennis (Hemiptera: Cicadellidae), a vector of the bacterium Xylella fastidiosa, which causes a variety of plant maladies, of which Pierce’s disease of grapes may be the best known. The second review will look at the classical biocontrol program targeting Asian citrus psyllid, Diaphorina citri (Hemiptera: Liviidae), that vectors the bacterium Candidatus Liberibacter asiaticus, the putative causative agent of the lethal citrus disease huanglongbing. Both of these case studies will draw on work in perennial outdoor crops/urban/wilderness areas, with a primary focus on what has been accomplished in California (USA) for H. vitripennis and D. citri, and the South Pacific (H. vitripennis only).