ARTHROPOD BIOLOGY Daily and Seasonal Patterns in Abdominal Color in Diaphorina citri (Hemiptera: Psyllidae) ERIK J. WENNINGER 1 AND DAVID G. HALL USDAÐARS, U.S. Horticultural Research Laboratory, 2001 South Rock Road, Fort Pierce, FL 34945 Ann. Entomol. Soc. Am. 101(3): 585Ð592 (2008) ABSTRACT Diaphorina citri Kuwayama, a psyllid vector of huanglongbing (citrus greening disease), exhibits three more or less distinct abdominal colors in the adult psyllid: gray/brown, blue/green, and orange/yellow. We explored the daily (in individuals in the laboratory) and seasonal (in a Þeld population) patterns in abdominal color of adult D. citri to clarify the biology of this species in relation to abdominal color and investigated the relationship between abdominal color and the reproductive state of adults (i.e., whether an individual is reproductively mature, has mated, orÑin femalesÑis gravid). Females were predominantly blue/green throughout their lives, with a small portion of individuals being gray/brown, especially just after emergence. Approximately 86% of mated females developed an orange/yellow abdominal color after mating, but they ultimately turned back to blue/green within several days to 1 mo after mating. Only 31% of virgin females turned orange/yellow. Males were predominantly blue/green early in life, but a greater portion of males relative to females were gray/brown. The orange/yellow color in females reßected the presence of eggs in the abdomen; in males it seemed to derive from the color of the internal reproductive organs, and it was generally only evident in older males. The preponderance of blue/green females, rarity of gray/brown females relative to gray/brown males, and rarity of orange/yellow males and females was largely reßected in sticky card trap captures from the Þeld. Abdominal color is of essentially no value in discerning the state of sexual maturity and of only limited value in discerning whether females have mated. KEY WORDS Asian citrus psyllid, body color, pigment, reproductive state, huanglongbing The psyllid Diaphorina citri Kuwayama (Hemiptera: Psyllidae) vectors three phloem-restricted, noncul- tured bacteria in the genus “Candidatus Liberibacter,” the causative agents of huanglongbing (citrus green- ing disease) (Halbert and Manjunath 2004, Hung et al. 2004, Bove ´ 2006). First found in Florida in June 1998 (Tsai et al. 2000), D. citri has since spread throughout the stateÕs citrus-growing regions (Michaud 2004). D. citri may cause direct feeding damage (Michaud 2004), but the primary economic importance of the psyllid is transmission of huanglongbing, one of the worldÕs most serious diseases of citrus (Bove ´ 2006). Huanglongbing was Þrst found in southern Florida in August 2005, and only “Candidatus Liberibacter asi- aticus” is known to occur in the state (Bove ´ 2006). Citrus trees infected by this disease may live only 5 to 8 yr, during which time they produce misshapen, poorly colored, bitter-tasting, unmarketable fruit (Halbert and Manjunath 2004, Bove ´ 2006). Despite the great economic importance of D. citri as a vector of huanglongbing, relatively little is known about the basic biology and ecology of this pest. Variation in body color has been described in nu- merous species in the Sternorrhyncha, and the clari- Þcation of the biological and ecological signiÞcance of such color polymorphisms remains an active area of research. Color variation in psyllids is generally asso- ciated with different seasonal forms in which the win- ter morphotype is darker, which presumably has a thermoregulatory function. Examples include the pear psylla, Cacopsylla pyricola (Fo ¨ rster) (Wong and Mad- sen 1967, Krysan and Higbee 1990); Cacopsylla mi- doriae (Miyatake) (Inoue 2004); Cacopsylla elegans Inoue (Inoue 2004); Cacopsylla chinensis (Yang & Li) (Yang et al. 2004); and Agonoscena pistaciae Burck- hardt & Lauterer (Mehrnejad and Copland 2005). Similar seasonal variation in body coloration also has been described in many species in the Aphididae (e.g., Watt and Hales 1996; Stoetzel and Miller 1998, 2001; Toros et al. 2003). Color polymorphisms in psyllids and aphids have generally been described in populations over time rather than at the level of individuals, and individual body color may not be dynamic for many species (but see Nevo and Coll 2001). Confusion has surrounded the characterization of different abdominal colors observed in D. citri, par- Mention of trade names or commercial products in this publication is solely for the purpose of providing speciÞc information and does not imply recommendation or endorsement. 1 Corresponding author, e-mail: erik.wenninger@ars.usda.gov.