Plant genotype effects on a host specific thrips and the impact on biological control

A promising thrips, Pseudophilothrips ichini has been considered for biological control of the invasive weed Brazilian pepper Schinus terebinthifolius. Originally collected from southern Brazil where it was frequently found associated with significant damage to its host. Subsequently this thrips was introduced into quarantine in Florida to determine its safety for release. However, a major limitation of the thrips population tested in quarantine was its apparent nutritional incompatibility with the genetic varieties of the host that occur in Florida. Although this thrips was collected on the host in Brazil, its survival was less than 5% when fed the Florida variety of Brazilian pepper. Extensive DNA and morphological analysis of the thrips has determined that the quarantined species is incorrectly identified and constitutes a new cryptic species Pseudophilothrips n. sp. Chloroplast DNA analysis of the host revealed 14 genetic varieties and the discovery that the new species of thrips was both limited geographically in Brazil and nutritionally to 2 Brazilian host varieties, neither of which occur in Florida. As a result of these studies, individuals of the species P. ichini have been correctly identified in Brazil. These thrips were found feeding on the Florida variety of the host in Brazil. Populations of P. ichini have been colonized and are undergoing quarantine testing in Florida to determine suitability for release to control the weed. By revealing thrips x host plant genetic compatibilities, these results have directed the next phase of quarantine testing of thrips that shows promise for controlling Brazilian pepper in Florida.