Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 4, 2013
Publication Date: N/A
Interpretive Summary: Beneficial insects are the primary means of controlling weeds that infest rangelands and natural areas in the U.S. Understanding the biological traits of these insects is important because it helps us improve management decisions, and thus, increase the impact of these insects on weeds. Two important, but difficult to study, traits are dispersal (movement patterns of the beneficial insects between patches of weeds), and predation (what insects are eating the beneficial insects?). Marking insects with immunoprotein labels is a useful approach to study dispersal and predation, but the label is costly and sometimes not active for as long as we would like – these factors can restrict the scope of research. We used immunoprotein labels in combination with dimethyl sulfoxide (a biological solvent) to determine if duration of the label on saltcedar leaf beetle was enhanced, and if the label could be transferred from prey (saltcedar leaf beetle) to predator (two-spotted stink bug). This work was done in the laboratory using saltcedar leaf beetles that had either ingested the label while eating foliage, or had been immersed in the label solution. Solvent-enhanced protein labels showed greater retention than protein labels without solvent. Immersion led to greater initial label values, and longer label retention than feeding beetles labeled foliage. The solvent-IgG label combination was readily transferred to predatory stink bugs after feeding on a single marked prey beetle. This study demonstrated that dimethyl sulfoxide enhances retention of protein labels, and that protein marking technology has potential for use in dispersal and predation studies with saltcedar leaf beetle.
Technical Abstract: Marking biological control agents facilitates studies of dispersal and predation. This study examines the effect of a biological solvent, dimethyl sulfoxide (DMSO), on retention of immunoglobulin G (IgG) protein solutions applied to Diorhabda carinulata (Desbrochers) (Coleoptera: Chrysomelidae) either internally by feeding them protein-labeled foliage or externally by immersing them in a protein solution. Additionally, we determined if internally or externally marked DMSO-IgG labels could be transferred via feeding from marked D. carinulata, to its predator, Perillus bioculatus (F.) (Heteroptera: Pentatomidae). The presence of rabbit and chicken IgG proteins was detected by IgG-specific enzyme-linked immunosorbent assays (ELISA). DMSO-IgG treatments showed greater label retention than IgG treatments alone, and this effect was stronger for rabbit IgG than for chicken IgG. Beetles immersed in rabbit IgG showed high (>90%) internal retention of label for 21 days after marking, while beetles immersed in chicken IgG showed 65% internal retention for 14 days after marking. Immersion led to greater initial (time 0) label values, and longer label retention than feeding beetles labeled foliage. The DMSO-IgG label was readily transferred to P. bioculatus after feeding on a single marked prey insect. This investigation shows that addition of DMSO enhances retention of IgG labels, and demonstrates that protein marking technology has potential for use in dispersal and predator-prey studies with D. carinulata. Moreover, our observation of P. bioculatus feeding on D. carinulata is, to our knowledge, a new predator-prey association for the stink bug.