Bioactivity and Molecular Responses of Bitter Gourd Leaf Extracts Against the Invasive Leafminer, Liriomyza trifolii (Diptera: Agromyzidae)

Abstract

Simple Summary Liriomyza trifolii is recognized as a destructive invasive pest affecting vegetable and ornamental crops worldwide, including China, where prolonged chemical insecticide use has led to reduced efficacy. In this study, the potential of bitter gourd (Momordica charantia) leaf extract as a botanical alternative was investigated. Host suitability tests demonstrated that L. trifolii exhibited significant oviposition and feeding adaptability for kidney bean over bitter gourd, with complete life cycle failure observed on the latter. Application of ethanol extracts resulted in dose-dependent adulticidal activity. At the LC50 concentration, feeding punctures and oviposition were notably reduced, and egg hatching and larval survival were significantly decreased, whereas pupation and emergence were not markedly affected. Integrative transcriptomic and metabolomic analyses were subsequently performed to elucidate underlying mechanisms, revealing 254 differentially expressed genes and 272 differential metabolites. Joint pathway analysis identified “Biosynthesis of amino acids” as the sole common pathway, with notable associations involving S-adenosyl-L-homocysteine, N-succinyl-LL-2,6-diaminoheptanedioate, and glutamine synthetase. These findings suggest that the reprogramming of amino acid and nitrogen metabolism may participate in the treatment response and could serve as a candidate response pathway. As such, this pathway may provide a theoretical basis for future development of plant-derived insecticides against L. trifolii.