Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2012
Publication Date: 10/1/2012
Citation: Serikawa, R., Rogers, M., Backus, E.A. 2012. Effects of soil-applied imidacloprid on Asian citrus psyllid (Hemiptera: Psyllidae) feeding behavior. Journal of Economic Entomology. 105(5):1492-1502. Interpretive Summary: The pathogen causing huanglongbing disease (HLB) of citrus is spread by the Asian citrus phyllid (ACP). Insecticides are extensively applied to citrus in Florida to reduce ACP populations but it is not known whether insecticide application disrupts feeding behaviors responsible for transmission of the HLB pathogen. Here, electrical penetration graph (EPG) monitoring was used to determine the effect of imidacloprid (Admire Pro) on ACP feeding behavior. A soil-applied insecticide, imidacloprid is taken up and spread systemically through the plant. Imidacloprid reduced ACP feeding activities associated with pathogen transmission (acquisition and inoculation). However, over 40% of insects on imidacloprid-treated young citrus leaves and 20% of insects on treated mature leaves performed some transmission-related feeding behaviors. Thus, despite the presence of imidacloprid in plants, pathogen transmission still may be possible, although possibly at a lower rate than on untreated plants.
Technical Abstract: The Asian citrus psyllid, Diaphorina citri Kuwayama is one of the most important pests of citrus due to its status as a vector of Candidatus Liberibacter asiaticus, the bacterium associated with huanglongbing (HLB) disease. The use of insecticides for vector control is the primary method of managing spread of the HLB pathogen. Imidacloprid is an insecticide commonly applied to the root zone of young citrus trees to provide systemic protection from pests. The effects of imidacloprid on feeding behavior of D. citri have not been studied in detail. Thus, the purpose of this study was to examine the effects of imidacloprid application on feeding behavior of D. citri, and to determine whether use of this systemic insecticide could have any direct effect on pathogen transmission by D. citri. A DC electrical penetration graph (EPG) monitor was used to record D. citri feeding behaviors for 12 h periods on mature and young leaves of imidacloprid-treated and -untreated citrus seedlings. Overall, when compared to untreated plants, the feeding behavior of D. citri was disrupted on imidacloprid-treated plants via reduction in the number of probes, as well as durations of average probes, initial stylet contact with phloem, phloem salivation, and phloem ingestion. However, 42.9% and 20.0% of psyllids feeding on imidacloprid-treated plants were still able to perform some phloem-related feeding behaviors on young and mature leaves, respectively. Thus, despite the presence of imidacloprid in plants, pathogen acquisition and/or inoculation still may be possible, albeit the rate at which they occur likely will be reduced compared with untreated plants.