Frequency of Secondary Symbiont Infection in an Invasive Psyllid Relates to Parasitism Pressure on a Geographic Scale in California

Two endosymbionts, an obligate primary symbiont and a facultative secondary symbiont, are harbored within the invasive red gum (eucalyptus) lerp psyllid,Glycaspis brimblecombei , in California. An extensive survey of diversity and frequency ofG. brimblecombei 's secondary symbiont in multiple populations throughout the state of California was conducted using PCR detection, restriction enzymes, cloning, and sequencing. A total of 380G. brimblecombei individuals in 19 populations were screened for secondary symbionts. Based on molecular screening results, only one type of secondary symbiont was present inG. brimblecombei populations in California. Overall, 40% of the 380 psyllids screened were infected with the secondary symbiont. Interestingly, secondary symbiont infection frequencies inG. brimblecombei populations varied dramatically from 0 to 75% and were significantly related to parasitism pressure byPsyllaphaegus bliteus , a solitary endoparasitoid of the psyllid.