CHAPTER 3 PESTICIDE SUSCEPTIBILITY OF Cybocephalus nipponicus AND Rhyzobius lophanthae (COLEOPTERA: CYBOCEPHALIDAE, COCCINELLIDAE) Introduction Beetles of the families Coccinellidae and Cybocephalidae are the most economically important groups of predators of diaspidid scales in the world (Blumberg and Swirski 1982). Cybocephalus nipponicus Endrody-Younga (Cybocephalidae) and Rhyzobius lophanthae Blaisdell (Coccinellidae) are commonly used as biological control agents for many armored scale pests. Rhyzobius lophanthae has been established in Florida since the 1930s (according to specimen label data in the Florida State Collection of Arthropods). Cybocephalus nipponicus, misidentified as Cybocephalus binotatus Grouvelle, was recently released in south Florida in an effort to control the cycad aulacaspis scale (CAS), Aulacaspis yasumatsui Takagi (Anon. 1998; Howard et al. 1999; Howard and Weissling 1999). CAS is the most economically damaging scale to cycads that the state of Florida has ever seen (Hodges et al. 2003). Although C. nipponicus is present in Hawaii (Heu and Chun 2000), R. lophanthae is usually suggested as the better control agent of CAS (Heu et al. 2003; A. Hara, personal communication). In both places, CAS has continued to spread and multiply. A more promising approach to controlling CAS would be one using integrated pest management (IPM). In this manner, a combination of pesticides and biological control would be used to combat CAS. There has been some success controlling CAS with various pesticides. Oils, either an ultra-fine horticultural oil or a product containing fish oils, seem to be the most