Quenching autofluorescence in the alimentary canal tissues of Bactericera cockerelli (Hemiptera: Triozidae) for immunofluorescence labeling.

Immunofluorescence has been widely used to localize microbes or specific molecules in insect tissues or cells. However, significant autofluorescence is frequently observed in tissues which can interfere with the fluorescent identification of target antigens, leading to inaccurate or even false positive fluorescent labeling. The alimentary canal of the potato psyllid, Bactericera cockerelli Šulc, exhibits intense autofluorescence, hindering the application of immunolocalization for the detection and localization of the economically important pathogen transmitted by this insect, "Candidatus Liberibacter solanacearum" (Lso). In the present study, we tested the use of irradiation, hydrogen peroxide (H2 O2 ) and Sudan black B (SBB) treatments to reduce the autofluorescence in the B. cockerelli alimentary canal tissues. Furthermore, we assessed the compatibility of the above-mentioned treatments with Lso immunolocalization and actin staining using phalloidin. Our results showed that the autofluorescence in the alimentary canal was reduced by irradiation, H2 O2 , or SBB treatments. The compatibility assays indicated that irradiation and H2 O2 treatment both greatly reduced the fluorescent signal associated with Lso and actin. However, the SBB incubation preserved those target signals, while efficiently eliminating autofluorescence in the psyllid alimentary canal. Therefore, herein we propose a robust method for reducing the autofluorescence in the B. cockerelli alimentary canal with SBB treatment, which may improve the use of immunofluorescence labeling in this organism. This method may also have a wide range of uses by reducing the autofluorescence in other arthropod species.