Do insects host undiscovered specialist eukaryotes?

Despite a growing appreciation of the functional role that host-associated organisms play in the biology of their host, microbiome studies have ostensibly ignored eukaryotic associates. This is despite well-known and biologically significant interactions between hosts and eukaryotic symbionts. However, applying a targeted metagenomic approach to the study of the eukaryotic community living on a eukaryotic host has a major methodological impediment: host templates dominate PCR reactions with universal primers, competitively excluding templates belonging to non-host eukaryotes from amplification. One solution to this problem is the use of PCR ‘blockers’. Blockers are host-specific DNA oligos with modified 3’ ends that prevent extension by Taq polymerase. When used with universal primers, blockers interfere with amplification of host DNA while allowing amplification of non-host DNA to proceed unaffected. I will discuss preliminary work to design a series of order-specific 18S blockers to target the five most species orders of insects and use blockers to survey the complete ‘eukaryomes’ of a taxonomically diverse array of insects.