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Title: Incidence of invasive Asian citrus psyllid, Diaphorina citri (Hemiptera: Psyllidae) and its introduced parasitoid Tamarixia radiata (Hymenoptera: Eulophidae) in Florida citrus

Author
item QURESHI, JAWWAD - UNIV OF FLORIDA
item ROGERS, MICHAEL - UNIV OF FLORIDA
item Hall, David
item STANSLY, PHIL - UNIV OF FLORIDA

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2008
Publication Date: 1/1/2009
Citation: Qureshi, J., Rogers, M., Hall, D.G., Stansly, P. 2009. Incidence of invasive Asian citrus psyllid, Diaphorina citri (Hemiptera: Psyllidae) and its introduced parasitoid Tamarixia radiata (Hymenoptera: Eulophidae) in Florida citrus. Journal of Economic Entomology. 102:247-256.

Interpretive Summary: The Asian citrus psyllid (ACP) vectors the bacterium Candidatus Liberibacter asiaticus, one of the causal organisms of Huanglongbing or citrus greening, a devastating disease of citrus. A parasitoid, Tamarixia radiata, was imported from Asia and released in Florida in 1999-2001 to improve biological control of ACP before citrus greening was detected in Florida in 2005. Studies conducted during 2006-2007 showed that ACP was well established in 28 citrus groves across 16 counties in Florida. Adults were detected during the growing and dormant seasons in the central, southwest and eastern coastal regions. T. radiata was recovered from fourth and fifth instar ACP nymphs at 26 of the 28 locations. However, apparent parasitism rates were variable and averaged less than 20% during spring and summer over all locations. Incidence of parasitism increased during fall at some locations, averaging 39% in Sep in the central region and 56% in Nov in the southwest region. These parasitism rates were lower than reported in Réunion, Guadaloup, and Puerto Rico, where significant suppression of psyllid populations has been reported. Weather, high levels of predation on parasitized nymphs, low nymphal populations for overwintering, or some genetic or biological characteristics of the T. radiata may be limiting its effectiveness in Florida. Therefore, further efforts are warranted to enhance the biological control of D. citri and thereby reduce psyllid populations and spread of citrus greening.

Technical Abstract: The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Psyllidae) vectors the bacterium Candidatus Liberibacter asiaticus, one of the causal organisms of Huanglongbing or citrus greening, a devastating disease of citrus. A eulophid parasitoid, Tamarixia radiata Waterson, was imported from Asia and released in Florida in 1999-2001 to improve biological control of ACP before citrus greening was detected in Florida in 2005. Studies conducted during 2006-2007 showed that D. citri was well established in 28 citrus groves across 16 counties in Florida. Adults were detected during the growing and dormant seasons in the central, southwest and eastern coastal regions. Adult populations averaged 3.52, 1.27, and 1.66 individuals per “tap” sample at locations in the central and southwest regions and along the east coast, respectively. Citrus flush infested with psyllid eggs or nymphs averaged 67% in the central region, 44% in the southwest and 45% along the east coast. T. radiata was recovered from fourth and fifth instar psyllid nymphs at 26 of the 28 locations. However, apparent parasitism rates were variable and averaged less than 20% during spring and summer over all locations. Incidence of parasitism increased during fall at some locations, averaging 39% in Sep in the central region and 56% in Nov in the southwest region. These parasitism rates were lower than reported in Réunion, Guadaloup, and Puerto Rico, where significant suppression of psyllid populations has been reported. Weather, high levels of predation on parasitized nymphs, low nymphal populations for overwintering, or some genetic or biological characteristics of the T. radiata may be limiting its effectiveness in Florida. Therefore, further efforts are warranted to enhance the biological control of D. citri and thereby reduce psyllid populations and spread of citrus greening.