Pesticide degradation capacity of the bug-Burkholderia symbiosis

When presented with a novel resource, microbes adapt. When this occurs within a symbiotic relationship, an insect host has the potential to benefit from the adaptation. This is particularly relevant for insects that acquire symbionts from the environment, as the bacteria have direct exposure to external conditions for a portion of their life cycle. This type of relationship is displayed by the western leaf-footed bug, Leptoglossus zonatus (Coreidae), and free-living soil bacteria in the genus Burkholderia. Symbiotic Burkholderia are acquired by the second instar of L. zonatus and are essential for their development. Furthermore, Burkholderia can also adapt to provide novel functions: In fields treated with the pesticide fenitrothion, the symbiont has previously been shown to adapt to degrade the pesticide and then, when ingested, to confer fenitrothion resistance to the bean bug Riptortus pedestris (Alydidae). However, the broader potential for this symbiotic relationship to provide pesticide resistance in Burkholderia-hosting bugs has not been quantified

We are testing 16 phylogenetically representative Burkholderia isolates from L. zonatus for the ability to degrade five commonly used agricultural pesticides: fenithrothion and malathion (organophophates), imidacloprid (neonicotinoids), permethrin (pyrethroids), and abamectin (macrocyclic lactones). We are assessing the potential for the development of degradative abilities by exposing five Burkholderia isolates to high concentrations of pesticides for 30 days. Currently, we have identified one isolate that can degrade imidacloprid out of 16 isolates tested. This suggests that symbiont-mediated pesticide degradation may be a common phenomenon that occurs for more types and classes of pesticide than just fenitrothion.