Suitability and attraction of flowers and aggregating thrips to the Brazilian peppertree biological control agent Pseudophilothrips ichini (Thysanoptera: Phlaeothripidae)

Brazilian peppertree, Schinus terebinthifolia (Anacardiaceae) is an invasive weed of natural and agricultural areas of Florida, Hawaii, and Texas (USA). Pseudophilothrips ichini is being released as a biological control agent for this invasive weed. The thrips feeds on flushing leaf tips that are produced during the vegetative season. However, during the weed reproductive season few flushing tips are available as resources are shunted to reproduction. As field releases are being implemented thrips were found apparently feeding and damaging fruits and flowers of their host. When examined under laboratory choice tests, solitary thrips adults, groups of 20 adults, and groups of 20 larvae chose leaf tips over all reproductive tissues, female flowers, male flowers, and green fruit. To emulate seasonal conditions when few flushing tips are available, an additional choice test was conducted that omitted leaf tips and only included reproductive tissues and a control. This choice test indicated that groups of adults and larvae preferred all reproductive tissues over controls.  Similar results occurred when adult thrips were evaluated individually. An additional test was included that evaluated the attraction of bagged aggregated P. ichini thrips to conspecific adults and larvae. Groups of adult thrips were not attractive to either conspecific thrips adults or larvae. These results suggest that the P. ichini thrips have flexible feeding habits exploiting Brazilian peppertree reproductive tissues during periods when few flushing tips are seasonally available. Moreover, bags may have interfered with thrips aggregation responses which prompts continued bioassay development.