Toxicity of Bacillus thuringiensis-derived pesticidal proteins Cry1Ab and Cry1Ba against Asian citrus psyllid, Diaphorinia citri (Hemiptera)

Authors: FERNANDEZ-LUNA, M. TERESA - Iowa State University; KUMAR, PAVAN - University Of Florida; Hall, David; Mitchell, Ashaki - Teddi; Blackburn, Michael - Mike; BONNING, BRYONY - Iowa State University

Submitted to: Toxins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/19/2019
Publication Date: 3/22/2019
Citation: Fernandez-Luna, M.T., Hall, D.G., Mitchell, A.D., Blackburn, M.B., Bonning, B.C. 2019. Toxicity of Bacillus thuringiensis-derived pesticidal proteins Cry1Ab and Cry1Ba against Asian citrus psyllid, Diaphorinia citri (Hemiptera). Toxins. 11(3):173-185. https://doi.org/10.3390/toxins11030173.
DOI: https://doi.org/10.3390/toxins11030173

Interpretive Summary: The Asian citrus psyllid (ACP) is an important pest because it transmits a serious disease of citrus called huanglongbing (HLB), also known as citrus greening disease. Insecticidal control of the psyllid is a key tactic used to manage the disease. We report on the toxicity of Bacillus thuringiensis (Bt) to the psyllid. Bt toxins with activity against ACP could be used for management of ACP and the associated HLB disease, and would provide a more sustainable and environmentally benign approach than repeated application of broad-spectrum insecticides.

Technical Abstract: The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera), is an important pest of citriculture. The ACP vectors a bacterium that causes huanglongbing (HLB), a devastating and incurable disease of citrus. The bacterium Bacillus thuringiensis (Bt) produces multiple toxins with activity against a diverse range of insects. In efforts to provide additional control methods for the ACP vector of HLB, we screened multiple strains of Bt for toxicity against ACP. The trypsin proteolytic profiles of toxin strains were characterized. Six Bt strains showed toxicity to adult ACP at 500 µg/mL of proteolytically activated toxin. One of the toxic strains (IBL-00200) was selected for LC-MS/MS identification of the individual Cry toxins expressed. Toxicity assays with individual toxins derived from IBL-00200 were then performed. The activated form of the Cry toxins Cry1Ab and Cry1Ba were toxic to ACP. Disruption of the midgut epithelium was associated with the toxicity of both IBL-00200 and Cry1Ba. Bt toxins with activity against ACP could be used for management of ACP and the associated HLB disease, and would provide a more sustainable and environmentally benign approach than repeated application of broad-spectrum insecticides.