IXth International Symposium on Thysanoptera and Tospoviruses

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

Greg S. Wheeler1*, D.A. Williams2 and L.A. Mound3

1USDA/ARS/IPRL, 3225 College Ave, Ft Lauderdale, FL, USA 33314
2Dept of Biology, Texas Christian University, 2300 S. University Dr, Ft Worth, TX, USA 76129
3CSIRO Entomology PO Box 1700, Canberra, ACT 2601, Australia

*Correspondence: greg.wheeler@ars.usda.gov

A promising thrips, Pseudophilothrips ichini (Phlaeothripidae) has been considered for biological control of the invasive weed Brazilian pepper Schinus terebinthifolius. This thrips was originally collected from a southern region of Brazil where it was frequently found associated with significant damage to its host. Subsequently this thrips was introduced into quarantine in Florida, USA to determine its safety for field release to control this weed. 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 two 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 colonised 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 the quarantine testing of this invasive weed that show promise for controlling this invasive weed in Florida.

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