Exogenous methyl jasmonate spray modulates Citrus × limon ( L .) Osbeck volatiles and impairs Trioza erytreae ( Del Guercio) development

BACKGROUND: Exogenous methyl jasmonate (MeJA) application induces plant defenses and modifies volatile organic compound (VOC) emissions. Understanding the effects of MeJA treatment on the VOC profile of lemon plants (Citrus × limon (L.) Osbeck) and on Trioza erytreae (Del Guercio), a vector of the citrus Huanglongbing pathogen, may contribute to the development of novel management strategies for this vector. RESULTS: Exogenous MeJA application reduced T. erytreae oviposition by 69.0% in lemon plants. While 94.9% of the eggs successfully developed into nymphs on untreated plants, only 53.6% reached the nymphal stage on MeJA-sprayed plants. Using headspace solid-phase microextraction (HS-SPME) in combination with gas chromatography-mass spectrometry (GC-MS) we found that both VOC emissions and endogenous JA levels were modulated by MeJA treatment and T. erytreae infestation. The isolated effect of adult psyllid feeding and oviposition had a greater impact on lemon plants 5 days after spray. The combined effect of MeJA spray and continuous nymphal feeding had a higher impact on lemon plants 25 days after spray. The response of lemon plants to MeJA spray and T. erytreae infestation was found to be associated with volatiles such as monoterpenes, sesquiterpenes, alcohols, esters and aldehydes. CONCLUSION: The exogenous application of MeJA induced VOC emissions and JA-related biochemical responses in lemon plants, significantly hindering T. erytreae infestation. These findings suggest that MeJA spray warrants further investigation as a complementary strategy for T. erytreae control. The utilization of MeJA in field settings merits further investigation in future field and semi-field studies. © 2026 Society of Chemical Industry.