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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Subtropical Insects and Horticulture Research » Research » Publications at this Location » Publication #304454
Title: Effect of Cyantraniliprole, a novel insecticide, on the inoculation of Candidatus Liberibacter asiaticus associated with citrus huanglongbing by the Asian citrus psyllid (Hemiptera: Liviidae)

Author
item Ammar, Eldesouky
item Hall, David
item ALVAREZ, JUAN - Dupont Crop Protection

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/6/2015
Publication Date: 2/17/2015
Citation: Ammar, E., Hall, D.G., Alvarez, J.M. 2015. Effect of Cyantraniliprole, a novel insecticide, on the inoculation of Candidatus Liberibacter asiaticus associated with citrus huanglongbing by the Asian citrus psyllid (Hemiptera: Liviidae). Journal of Economic Entomology. doi: 10.1093/jee/tov016.

Interpretive Summary: The Asian citrus psyllid is the principal vector of the bacterium associated with huanglongbing (citrus greening), the most serious citrus disease worldwide. New research tools and control measures are urgently needed to combat the disease, and protecting newly planted trees from inoculation by psyllids is of critical importance. Here, we tested the ability of infected psyllid adults to inoculate excised healthy citrus leaves treated with a new insecticide, Exirel® compared with a grower standard, Danitol® 2.4EC. Significantly fewer psyllids were observed to settle (feeding/probing) on leaves with fresh dry residues of Exirel® than those with residues of Danitol® or water controls. Adults on leaves treated with Exirel® died at a slower rate than those treated with Danitol®, but cumulative mortality did not differ between the two treatments. The ability of infected psyllid adults to inoculate citrus leaves was significantly higher in psyllids on untreated leaves than those on leaves treated with Exirel® or Danitol®. Our results suggest that Exirel® significantly reduces transmission primarily by reducing psyllid feeding.

Technical Abstract: The Asian citrus psyllid (Diaphorina citri Kuwayama) is the principal vector of Candidatus Liberibacter asiaticus (LAS) associated with huanglongbing (HLB), the most serious citrus disease worldwide. New research tools and control measures are urgently needed to combat HLB, and protecting newly planted trees from LAS-inoculation by psyllids is of critical importance. Here, we tested the ability of bacterioliferous psyllid adults (reared on LAS-infected plants) to inoculate LAS into excised healthy citrus leaves treated with a new insecticide, Exirel® (active ingredient cyantraniliprole = Cyazypyr®), compared with a grower standard, Danitol® 2.4EC (active ingredient fenpropathrin). Significantly fewer psyllids were observed to settle (putatively feeding/probing) on leaves with fresh dry residues of Exirel® than those with residues of Danitol® or water controls. Adults on leaves treated with Exirel® died at a slower rate than those treated with Danitol®, but cumulative mortality did not differ between the two treatments. In RT-PCR tests, 59.0-65.3% of the psyllids in these transmission studies were LAS-positive. The ability of bacterioliferous psyllid adults to inoculate LAS into citrus leaves was significantly higher in psyllids on untreated leaves (47.5-85% transmission) than those on leaves treated with Exirel® or Danitol® (2.5-12.5% transmission). Our results suggest that Exirel® significantly reduces transmission of LAS primarily by reducing psyllid feeding. Additionally, we demonstrated that the excised leaf assay method, which takes only a few weeks compared to a year or longer using whole plants, is an effective tool for testing the effect of new pesticides or other treatments in reducing LAS inoculation into healthy citrus.