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Response of Diaphorina citri (Hemiptera: Liviidae) to volatiles characteristic of preferred citrus hosts

Amorós, María Eugenia, Pereira das Neves, Virginia, Rivas, Fernando, Buenahora, José, Martini, Xavier, Stelinski, Lukasz L., Rossini, Carmen
Arthropod-plant interactions 2019 v.13 no.3 pp. 367-374
Citrus paradisi, Citrus sinensis, Diaphorina citri, adults, aeration, attractants, beta-caryophyllene, beta-ocimene, etiological agents, gas chromatography-mass spectrometry, grapefruits, greening disease, hosts, insects, limonene, methylene chloride, monitoring, odors, oranges, pests, solvents, sticky traps, volatile compounds
The Asian citrus psyllid, Diaphorina citri, is currently the most important pest of citrus worldwide because it vectors ‘Candidatus Liberibacter’ spp., the etiological agents of lethal Huanglongbing (HLB). Reduction of D. citri populations is a key component of HLB management. Identifying potential D. citri attractants, such as volatiles, could be useful for behavioral management of this insect. This could, for instance, enhance catches of adults on monitoring traps. The overall aim of this study was to investigate the response of D. citri to volatiles characteristic of preferred citrus hosts. An ancillary objective was to formulate a synthetic blend of volatiles based on preferred host odors that could enhance monitoring traps. Volatile collections of two preferred citrus species, Duncan grapefruit (Citrus paradise) and sweet orange (Citrus sinensis), were performed in aeration chambers and analyzed by gas chromatography-mass spectrometry. Based on the grapefruit volatile profile, a synthetic blend consisting in D-limonene (0.62 mg), methyl N-methylanthranilate (0.19 mg), β-ocimene (0.11 mg), β-elemene (0.02 mg), and β-caryophyllene (0.02 mg) was prepared in 9.9 mL of dichloromethane and evaluated for attractiveness, as well as the individual compounds, and compared with a positive control of natural volatiles collected from Citrus sinensis. Behavior of D. citri adults was evaluated in two-choice behavioral assays comparing response to lures with different combinations and dosages of the volatiles deployed on yellow sticky traps. Individually, neither D-limonene nor methyl N-methylanthranilate affected behavior of D. citri. However, these volatiles increased catches of D. citri, as compared with solvent control, when presented as components of the synthetic grapefruit blend, as did the natural citrus odor positive control. Importantly, catch of D. citri appeared to vary with the release rate of the identified grapefruit volatile blend, which was attractive at a 0.1 mg loading dosage, but repellent at a dosage only 1 log step higher.