Background Herbivores may influence each other directly and through plant mediated inter‐specific interactions. The Asian citrus psyllid (Diaphorina citri Kuwayama) and citrus aphids are key pests that can co‐exist on citrus, but their plant‐mediated interaction between them is unknown. Here we investigated plant‐mediated effect of two citrus aphid species, the polyphagous Aphis spiraecola Patch and the oligophagous Aphis (Toxoptera) citricidus (Kirkaldy) on the feeding behavior and reproduction of Diaphorina citri, and explored the underlying mechanisms. Results In comparison with those on aphid free plants, Diaphorina citri had decreased reproduction and reduced phloem feeding on Aphis spiraecola pre‐infested plants, while the reproduction and feeding efficiency were increased on Aphis citricidus pre‐infested plants. Jasmonic acid (JA) dependent defense was significantly activated by Diaphorina citri feeding on Aphis spiraecola pre‐infested plants, but was suppressed by Diaphorina citri feeding on Aphis citricidus pre‐infested plants compared with that on aphid free plant. By contrast, only one tested marker gene in salicylic acid (SA) signaling was activated by Diaphorina citri feeding on Aphis spiraecola pre‐infested plants. Furthermore, exogenous application of methyl jasmonate, but not SA, conferred resistance against Diaphorina citri in our citrus trials. Conclusion Our results indicate that pre‐infestation by two citrus aphid species differentially altered Diaphorina citri induced citrus JA dependent defense, which resulted in different effect on subsequent Diaphorina citri performance. © 2022 Society of Chemical Industry.

Plants grown with vermicompost amendments are known to be harmful to sap-sucking insects, but the underlying mechanism remains to be determined. Here we investigated the feeding behavior of Diaphorina citri Kuwayama on Citrus limon (L.) Burm. F using the electrical penetration graph technique. Plants were grown in soil with different vermicompost rates (0%, 20%, 40%, and 60% w/w). Additionally, plants were tested for the activity of salicylic acid (SA) and jasmonic acid (JA) pathway-related enzymes. When compared to the control, vermicompost treatments (40% and 60%) decreased duration of phloem sap feeding and increased duration of the pathway phase of D. citri, and the 60% vermicompost made it more difficult for D. citri to reach and gain access to phloem sap. Enzymatic assays indicated that the 40% amendment rate increased phenylalanine ammonia lyase (involved in the SA pathway) and polyphenol oxidase (involved in the JA pathway), while the 60% amendment rate increased -1,3-glucanases (involved in the SA pathway) and lipoxygenase (involved in the JA pathway). The 20% amendment rate had no effect on feeding or enzyme activities. This study revealed that vermicompost amendments can reduce the efficiency of D. citri feeding, which may result from increased plant resistance via the SA and JA pathway.