Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is the vector of huanglongbing (HLB), the most devastating disease of citrus worldwide. Knowledge of ACP dispersal behavior in locating host plants may contribute to our understanding of the spread of HLB within and between citrus trees. We conducted research in laboratory to evaluate ACP host plant finding behavior. In a free-choice situation, ACP adults initially settled at equal rates among seedlings of Rhododendron simsii (non host plant for ACP), Murraya panciculata and “Lugan”Citrus reticulata. However, at 18 and 42 h after ACP were released, the mean number of adults per plant on R. simsii was significantly lower than on C. reticulata and M. paniculata, respectively. Numbers of adults on C. reticulata and M. paniculata remained statistically equivalenty until 90 h after releases. Within a plant, the ratio of ACP adults on new flush shoots did not significantly increased in comparison to other parts of the tree during 1-4 d after the psyllids were released. Even on 7^th day after ACP release, about 30 % adults were observed on plant locations other than flushing shoots. The results indicated that ACP adults differentiated between host and non-host plants faster than they differentiated between different parts of a host plant.

Huanglongbing (HLB) is the most devastating disease of citrus worldwide and vectored by the Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Psyllidae). The pathogen associated with HLB maintains uncultural in vitro, and there are few effective options against HLB-affected plants. Identification and deployment of ACP- resistance traits of citrus and citrus related germplasm to suppress ACP populations may be a potential management strategy for the management of HLB. In the present study, the susceptibilities of 71 Chinese citrus genotypes to ACP infestation were evaluated and analyzed in a free-choice situation under field conditions by using the method of systematic clustering and dynamic clustering. The results showed that there was significant difference in susceptibility to ACP infestation among the genotypes of citrus. These genotypes can be graded according to the number of psyllids on the trees. Grade I: highly susceptible with a total of 8 genotypes. Grade II: moderately susceptible with a total of 18 genotypes. Grade III: lower susceptibility with a total of 45 genotypes. The 71 genotypes of citrus are used to be classified into 8 groups according to the Chinese classification system “Citrus Varieties in China” (Chinese Citrus Association). There existed significant differences among the 8 groups. Lemons and Pummelos were highly susceptible hosts to ACP, with no significant difference from Murraya panciculata L., which was the most suitable host to ACP. Mandarins, Hybrid citrus, Sweet oranges and Tangerines were moderately susceptible hosts. Kumquat and Sour oranges were lower susceptible hosts. Some genotypes of Kumquat, like Citrus medurenisi var. Variegated Calamondin, Fortunella hindsii var. Chintou, and Sour orange, Citrus aurantium var. Variegated sour orange, had the lowest susceptiblility to ACP infection. Further experiment will be done to confirm the low ACP- susceptibility of genotypes from Kumquat and Sour orange.