SPECIAL ISSUE – IMPROVING PEST CONTROL: MASS REARING AND FIELD PERFORMANCE Quarantine host range testing of Pseudophilothrips ichini, a potential biological control agent of Brazilian peppertree, Schinus terebinthifolia, in North America and Hawaii Gregory S. Wheeler 1 *, Veronica Manrique 2 , William A. Overholt 2 , Fernando McKay 3 & Kirsten Dyer 1 1 USDA/ARS Invasive Plant Research Lab, 3225 College Ave, Ft Lauderdale, FL 33314, USA, 2 Biological Control Research and Containment Laboratory, University of Florida, 2199 South Rock Road, Ft Pierce, FL 34945, USA, and 3 FuEDEI, USDA/ARS/SABCL, Buenos Aires, Argentina Accepted: 2 May 2016 Key words: biological control of weeds, Anacardiaceae, Thysanoptera, Phlaeothripidae, host range tests, thrips Abstract Brazilian peppertree, Schinus terebinthifolia Raddi (Anacardiaceae), is an invasive weed of natural and agricultural areas of Florida, Hawaii, and Texas (USA). Biological control presents an environmen- tally safe and cost-effective control method for invasive populations of this weed. Though many potential agents have been tested for specificity, nearly all have been rejected due to a broad host range. However, one species, a thrips Pseudophilothrips ichini (Hood) (Thysanoptera: Phlaeothripi- dae), shows promise from field observations and quarantine host range tests. A series of no-choice, choice, and multiple-generation tests was conducted on 127 plant taxa (including five mango and four pistachio varieties) from 45 families and 33 orders. In no-choice starvation tests, the thrips fed and produced offspring on the target weed (124 F 1 adults per plant), whereas no or few (<4F 1 adults per plant) were obtained on non-target species. The primary exception was another exotic invasive tree Schinus molle L., on which an average 20 F 1 thrips adults were produced. No-choice tests indi- cated that small numbers of F 1 offspring were produced on nine other non-target plant species. The numbers of F 1 offspring produced on these plants were <3% of those produced on the target weed. In choice tests, on average two or fewer F 1 adults were produced on four non-target species tested, com- pared with 64 F 1 adults on the target weed. Multiple-generation tests indicated that three generations of thrips were maintained only on the target weed and S. molle with no differences between these two plant species or across generations. Thus, this thrips species has a narrow host range that includes the two invasive Schinus spp. tested here. If released, the thrips P. ichini will constitute safe and poten- tially effective biological control of Brazilian peppertree in North America and Hawaii. Introduction Brazilian peppertree, Schinus terebinthifolia Raddi (Anacar- diaceae), native to South America, is one of the most aggressive and widespread invasive species in Florida, Hawaii, and Texas (USA) (Ewel, 1986; Rodgers et al., 2014). This species constitutes a threat to natural areas, agriculture, and cattle production (Morton, 1978; Ewel, 1986; Yoshioka & Markin, 1991). Brazilian peppertree, also known as Christmas berry in Hawaii, has successfully colonized most of the Florida peninsula, covering more than 280 000 ha (700 000 acres), with thick monospecific stands that eliminate understory plant growth (Ferriter, 1997; Schmitz et al., 1997). In Hawaii, surveys conducted in the early 1990s estimated that 50 000 ha were moder- ately to heavily infested by this noxious weed (Yoshioka & Markin, 1991). In Texas, Brazilian peppertree occurs along *Correspondence: Gregory S. Wheeler, USDA/ARS Invasive Plant Research Lab, 3225 College Ave, Ft Lauderdale, FL 33314, USA. E-mail: greg.wheeler@ars.usda.gov 204 © 2016 The Netherlands Entomological Society Entomologia Experimentalis et Applicata 162: 204–217, 2017 DOI: 10.1111/eea.12506