Ecology and vectorship of the citrus psyllid in relation to the prevalence of citrus huanglongbing

Citrus huanglongbing is the most serious disease of citrus in Taiwan. For the control of the disease, citrus budwood registration and certification program has been operating since 1983. Once the healthy seedlings are planted out in the field, control of huanglongbing depends on control of the psyllid vector. The ecology and vectorship of the citrus psyllid in relation to the prevalence of citrus huanglongbing and the control measures of citrus psyllid are discussed in this paper. The efficiency of huanglongbing transmission is related to high vector population, percentage of psyllids carrying pathogens and vector dispersal activity. The epidemic follows the normal sigmoid- shaped curve. The disease is cumulative and increases over time, depending on the abundance of the vector and the availability of infected plants. It starts slow, increases gradually year after year until it reaches the exponential stage and only then the epidemic increases rapidly. Control strategy is to prevent disease damage from exceeding the level where profit or required yield is significantly diminished.