Toxic Peptides in Populations of Two Pergid Sawflies, Potential Biocontrol Agents of Brazilian Peppertree.

ABSTRACT

Determination of the safety of agents prior to release is one of the most important research goals in biological control. In addition to concerns for the safety of non-target plants, determination of the potential toxic properties of new agents needs to be assessed. Numerous phytophagous insects are defended by chemicals against the attack of natural enemies. Some of these defensive compounds could pose an environmental risk if an agent is released. Here, larval populations of two pergid sawflies, Heteroperreyia hubrichi and H. jorgenseni, were analyzed by LC-MS/MS to investigate whether they contain alleged toxic peptides. The first species is a potential candidate for biological control of the invasive weed Brazilian peppertree in Florida and Hawaii. The chemical analyses revealed the presence of the peptides pergidin (Perg), 4-valinepergidin (VPerg), dephosphorylated pergidin (dpPerg), lophyrotomin (LGln and LGlu). The effect of sawfly population for each species was significantly influencing peptide concentration. All peptides occurred at lower concentrations compared with purportedly toxic species of this sawfly family. However, the concentrations of the peptides are of concern for the welfare of wildlife and livestock that would be exposed to these species. These results demonstrate that release of this biological control agent in the invaded range may pose an environmental threat.