Chemical and behavioral analysis of the cuticular hydrocarbons from Asian citrus psyllid, Diaphorina citri

Abstract

Huanglongbing (HLB) is the most destructive disease of citrus worldwide. The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is the vector of the phloem-inhabiting bacterium, Candidatus Liberibacter asiaticus, which is presumed to cause HLB in Florida citrus. Laboratory and field studies were conducted to examine the behavioral responses of male and female D. citri to their cuticular extracts. In olfactometer assays, more male D. citri were attracted to one, five, or 10 female cuticular extract equivalent units than blank controls. The results were confirmed in field studies in which clear or yellow traps baited with 10 female cuticular extract equivalent units attracted proportionately more males than clear traps baited with male cuticular extract or unbaited traps. Analyses of cuticular constituents of male and female D. citri revealed differences between the sexes in chemical composition of their cuticular extracts. Laboratory bioassays with synthetic chemicals identified from cuticular extracts indicated that dodecanoic acid attracted more males than clean air. Traps baited with dodecanoic acid did not increase total catch of D. citri as compared with blank traps at the dosages tested; however, the sex ratio of psyllid catch was male biased on traps baited with the highest lure loading dosage tested (10.0 mg).

The Long and the Short of Mate Attraction in a Psylloid: do Semiochemicals Mediate Mating in Aacanthocnema dobsoni Froggatt?

“…These compounds were present in quantities that varied according to sex and age. While sex linked differences appear to be important for mate attraction in C. pyricola and D. citri (Guédot et al 2009b; Mann et al 2012, we found no similar evidence for A. dobsoni. We suggest that age related differences in the CHCs of A. dobsoni probably reflect losses through abrasion given that the molecular weights and boiling points of most of the CHCs are probably too high for them to volatilize to any significant extent.…”

“…Sex related differences in CHC profiles also have been reported in C. pyricola and D. citri (Guédot et al 2009b; Mann et al 2012 females produce higher quantities of 13 MeC compared to post diapause males (Guédot et al 2009b ), while D. citri females produce more C H O compared to conspecific males (Mann et al 2012 ). We also found that the CHC profiles of both sexes vary with age.…”

“…Two compounds, 13 methylheptacosane and dodecanoic acid, have been identified as "long-range" sex attractants in C. pyricola and D. citri, respectively (Guédot et al 2009b; Mann et al 2012. Given a putative upper molecular weight (MW) limit for airborne sex pheromones of about 300, 13 methylheptacosane (MW = 395) is, at best, barely volatile and likely to function at short range only Vehrencamp 2011b ; Lubanga et al 2014 ).…”

“…Given a putative upper molecular weight (MW) limit for airborne sex pheromones of about 300, 13 methylheptacosane (MW = 395) is, at best, barely volatile and likely to function at short range only Vehrencamp 2011b ; Lubanga et al 2014 ). Although dodecanoic acid (MW = 200) is sufficiently light to act at long range, it failed to attract D. citri males under field conditions (Mann et al 2012 ). Dodecanoic acid has a melting point of 44-46 °C and a boiling point of 225 °C at 100 mmHg (Pence and Williams 2010 ).…”

“…Although not previously reported in Psylloidea (Sternorrhyncha), age related differences in CHC profiles have been reported in Heteroptera, e.g., the Bean bug (Riptortus pedestris) (Alydidae) (Yoon et al 2012 ). In Psylloidea, the use of sex related differences in CHC profiles for mate attraction has received considerable attention (Guédot et al 2009b; Mann et al 2012 ). However, age-related differences in CHC profiles as indicators of mate quality have been ignored.…”