Behavioral Responses of Asian Citrus Psyllid (Hemiptera: Liviidae) to Salinity-Stressed Citrus

Most commercial citrus varieties are intolerant of salinity stress, but some rootstocks, such as Rangpur lime, tolerate moderately saline irrigation water. Development of salinity-tolerant citrus may allow for citriculture in semiarid and arid regions where salinity stress is problematic. Because salinity stress influences shoot growth in citrus, we compared the behavioral responses of Asian citrus psyllid, Diaphorina citri Kuwayama, to salinity-stressed versus nonstressed Rangpur lime seedlings. The effects of salinity stress on key physiological processes in the seedlings were also examined. Seedlings in the control group were fertilized with a solution having a salinity of 1.7 dS m(-1)while seedlings in the salinity-stressed group were fertilized with a solution having a salinity of 10 dS m(-1). The seedlings were exposed to salinity stress for increasing durations (15, 20, or 60 d). Seedlings presented differential physiological responses 15 d after the imposition of salinity stress, and differences in psyllid settling rate on control versus salinity-stressed seedlings were discernable within 1 h following the imposition of salinity stress.The levels of settling, oviposition, and egg survivorship were significantly lower on salinity-stressed versus control seedlings. Olfactometer tests showed that female psyllids preferred the odor from control seedlings, suggesting that the odors of control and salinity-stressed seedlings were different. The results showed that D. citri avoids salinity-stressed seedlings; this suggests the possibility of using moderate salinity stress as a management strategy to minimize psyllid settlement and reproduction and to reduce the spread of huanglongbing, especially in citrus grown in semiarid and arid areas.