Connecting gut contents to insect feeding/probing behavior and implications for data interpretation

Molecular gut contents analysis is a method which sequences regions of the chloroplast and internal transcribed spacer (ITS) DNA from plant material ingested during feeding to identify prior plant hosts. This method can be used with hemipteran phloem feeders, including aphids. It is not clear which plant tissues aphids are ingesting detectable plant DNA from, however. For example, aphids exhibit exploratory probes during which the intracellular contents of epidermal cells are ingested to assess plant-host suitability prior to pursuing phloem ingestion. Using electropenetrography, we compared the likelihood of plant DNA detection following exploratory probes (as might be seen on a non-host plant) versus phloem feeding (as would be seen on a palatable host plant). Using electropenetrography could inform how gut contents analysis can be interpreted to infer aphid behavioral and dispersal patterns in the field.