Herbivore-induced plant volatiles emitted by citrus in response to spider mite infestation can attract predatory mites

Understanding the nutritional interplay among plants, pests, and natural enemies is essential for sustainable pest management. Enhancing the efficiency of natural enemies, such as Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) is critical, and exploiting herbivore-induced plant volatiles (HIPVs) offers a promising approach. However, N. californicus has rarely been reported to utilize HIPVs to improve their biological control capabilities. Our research revealed a significant difference in the diversity of volatile compounds detected in clean Citrus reticulata Blanco leaves compared to those in C. reticulata leaves infested with Panonychus citri (McGregor) (Acari: Tetranychidae), regardless of mite presence. This suggests that P. citri infestation induces a wide array of HIPVs in C. reticulata leaves. We conducted olfactory behavioral assays to evaluate the response of N. californicus to synthetic HIPVs. Results revealed that linalool (1.00 mg/mL), 2,2,4-trimethylpentane (10.0 mg/mL), undecylcyclohexane (1.00 mg/mL), and (+)-dibenzoyl-L-tartaric anhydride (10.0 mg/mL) significantly attracted N. californicus while pentadecanal (1.00 mg/mL) significantly deterred it. A 3-component blend of linalool, undecylcyclohexane, and (+)-dibenzoyl-L-tartaric anhydride was better than other combinations in attracting N. californicus. This combination provided the basis for developing an attractant for N. californicus, facilitating the rate of its dispersal to enhance its biological control of pests. Consequently, this research offers vital insights into improving the sustainable pest control potential of predatory mites.