Characterization of mechanisms of host plant resistance against Asian citrus psyllid (ACP), Diaphorina citri (Hemiptera: Psyllidae)

Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, vectors Candidatus Liberibacter asiaticus (Ca. Las) the causal agent of huanglongbing (HLB) disease in citrus. Host plant resistance against Ca. Las or ACP is presumed to be one of the most sustainable approaches to mitigate the impact of HLB on citrus production. However, development of host plant resistance to ACP feeding and/or transmission could be a more effective approach to HLB management than finding resistance to Ca. Las alone because plants moderately resistant to the pathogen alone may not prevent successful acquisition and inoculation. In the current investigations we identified sources of resistance against ACP which could be used for lowering the transmission of Ca. Las. Trifoliate orange Poncirus trifoliata was less attractive to D. citri than sweet orange (Citrus sinensis), sour orange (C. aurantium), rough lemon (C. jambheri), grape fruit (C. paradisi) or swingle C. aurantifolia) citrus plants in laboratory olfactometer assays. In settling experiments fewer psyllids settled on P. trifoliata than on other citrus host plants. The underlying biophysical (antixenosis) and biochemical (antibiosis) factors for the lower suitability of P. trifoliata as compared with other varieties and their influence on Ca. Las transmission efficiency by ACP will be discussed.