Olfactory selection preference of Diaphorina citri toward different citrus varieties

The citrus industry is one of the most important pillar of China's agricultural economy, but it has been widely devastated by Citrus Huanglongbing (HLB), leading to severe economic losses. Asian citrus psyllid (Diaphorina citri) is the natural vector of Citrus HLB, and its host selection preference plays a crucial role in disease transmission. To clarify the selection preference of D. citri for six citrus varieties—including C. reticulata 'Shatangju', C. reticulata var. 'Gonggan', C. limon, C. sinensis × Poncirus trifoliata, C. junos cv., and Fortunella hindsii—Y-tube olfactometer was used to measure the attraction of D. citri to these varieties and the volatiles of the most preferred citrus variety. Additionally, chemical analysis was also conducted to determine the nutrient content in the most preferred citrus organs. The results showed that D. citri adults preferred C. reticulata 'Shatangju', and mechanical stimulation (leaf-cutting) altered their host selection but had limited impact on the ranking of their preferences. Adults preferred feeding on the tender shoots of C. reticulata 'Shatangju', which contained higher levels of total protein, total lipids, and total sugars. Among the volatile components of C. reticulata 'Shatangju', adults have the highest tendency rate towards 1 μL/mL 3-carene. The volatile components with significant higher tendency rates than the control group also include 10 μL/mL 3-carene, 0.1 μL/mL D-limonene, 0.05 μL/mL α-terpinene, 1 μL/mL trans-2-hexenal, and 10 μL/mL hexanal. Volatile components of host plant and the nutrient content of plant organs were identified as the main factors influencing the host selection preference of D. citri adults. The study confirmed that adults of D. citri exhibit an olfactory selection preference for C. reticulata 'Shatangju'. These findings on host selection preference provide new ways for the ecological control of D. citri and Citrus Huanglongbing.