Biological Science Technician USDA-ARS Dania Beach, Florida
A thrips, Pseudophilothrips ichini is being released for biological control of Brazilian peppertree, Schinus terebinthifolia (Anacardiaceae), an invasive weed of natural and agricultural areas of California, Florida, Hawaii, and Texas (USA). The thrips larvae and adults feed on flushed leaves produced during the vegetative season. However, during the reproductive season, few flushing leaves are available as resources are shunted to plant reproduction. As field releases were being implemented, thrips were found feeding and damaging immature fruits and flowers of their host. Possibly, the thrips used volatile organic compounds produced by reproductive tissues. When examined under laboratory choice tests, individual thrips or groups of either 20 adults or larvae, chose flushing leaves over all reproductive tissues, female flowers, male flowers, and immature fruit. However, to approximate seasonal conditions when few flushing leaves were available, additional choice tests were conducted where flushing leaves were omittedhrips selected all reproductive tissues over controls. When presented with a choice between immature and mature fruit, thrips chose immature fruit. Thrips caused significant damage to live female flowers, male flowers, and immature fruit, and thrips survival rates were similar when fed flush leaves, female flowers, or male flowers. The thrips responses could be tied to VOC production, which varied between each tissue type. These results suggest that the P. ichini have a flexible feeding strategy and exploit Brazilian peppertree reproductive tissues when few flushing tips were available. Further they suggest that thrips feeding will have direct impacts on Brazilian peppertree reproduction
