To date, three greenhouse/growth chamber studies have been completed, testing the effects of six different commercial formulations of plant growth regulators (PGRs) on the fitness (survival and oviposition) of the Asian citrus psyllid. The PGRs tested include Apogee (prohexadione calcium), Profile (paclobutrazol), Embark (mefluidide), Atrimmec (dikegulak-sodium), Sumagic (uniconazole), and Cycocel (chlormequat chloride). In both of the studies that included Atrimmec, significant phytotoxicity was observed in the form of foliage burn and dieback, thus preventing new growth and psyllid oviposition and survival. The other PGRs reduced shoot growth between 3 and 50% relative to untreated controls. Significant differences were observed in the number of eggs laid by psyllids on plants treated with different PGR’s. Oviposition was reduced by approximately 85% on plants treated with Embark and Sumagic, and by 65% on plants treated with Apogee and Profile relative to untreated controls, whereas oviposition was increased by 30% on plants treated with Cycocel Significant differences in survivorship of psyllid nymphs to adults were observed between the different PGR treatments. Survival was lowest for plants treated with Profile (7%), followed by Sumagic (36%), untreated control plants (45%) and Apogee (47%). The highest survivorship rates were observed on Cycocel (73%) and Embark (68%) treated plants. Survivorship of psyllids on plants treated with Profile was significantly lower than on plants treated with Cycocel and Embark, while all the other treatments did not differ significantly. There were significant differences in the weight of the adult psyllids reared on plants treated with the different PGRs. Adults emerged from plants treated with Sumagic weighed less than all the others with the exception of psyllids reared on Cycocel treated plants. Weight of psyllids reared on plants treated with Profile, Embark and Apogee did not differ significantly from the control. These results have been presented at the Plant Growth Regulation Society of America (Aug 2009), the Entomological Society of America (Dec 2009) and the Western Plant Growth Regulator Society (Jan 2010). It is important to note that none of the products tested to date are currently labeled for use on citrus, although Apogee and Sumagic are currently labeled for use on apples and vegetable transplants, respectively, whereas the others are only labeled for ornamental crops. Thus future greenhouse and growth chamber studies will focus on determining the plant physiological and/or metabolic changes that are occurring which are affecting psyllid behavior. Understanding these changes may allow for the selection of plants with these traits inherent or their selection in plant breeding efforts, or open avenues of research into other means of psyllid control by targeting specific biological needs of the insect. In addition, other rates and chemistries of PGRs will be tested. Field trials are planned to begin the spring of 2010.