As the predominant pest of alfalfa, Odontothrips loti Haliday causes great damages over the major alfalfa-growing regions of China. The characteristics of strong mobility and fecundity make them develop rapidly in the field and hard to be controlled. There is a shortage of bioinformation and limited genomic resources available of O. loti for us to develop novel pest management strategies. In this study, we constructed a chromosome-level reference genome assembly of O. loti with a genome size of 346.59 Mb and scaffold N50 length of 18.52 Mb, anchored onto 16 chromosomes and contained 20128 genes, of which 93.59% were functionally annotated. The results of 99.20% complete insecta_odb10 genes in BUSCO analysis, 91.11% short reads mapped to the ref-genome, and the consistent tendency among the thrips in the distribution of gene length reflects the quality of genome. Our study provided the first report of genome for the genus Odontothrips, which offers a genomic resource for further investigations on evolution and molecular biology of O. loti, contributing to pest management.

Plant-derived volatile organic compounds (VOCs) are widely used as insect attractants for population monitoring, offering an efficient and eco-friendly approach to pest management. Since thrips are the dominant pest species in alfalfa (Medicago sativa) crops, alfalfa volatiles produced in the presence of Odontothrips loti and compounds with attractive potential to both O. loti and Frankliniella occidentalis were investigated. Using gas chromatography–mass spectrometry (GC-MS), 96 VOCs were identified from seven alfalfa cultivars with varying levels of thrips resistance with and without damage by O. loti. Eleven volatiles were selected for Y-tube olfactometer assays. The semiochemical p-Menth-8-en-2-one, which was suppressed in alfalfa subject O. loti damage, significantly attracted both O. loti and F. occidentalis in Y-olfactometer bioassays; the response rates were 2.05~3.07 times compared to control (p < 0.05). Further experiments confirmed p-Menth-8-en-2-one, dispensed through PE (Polyethylene) vials, was the most effective lure material with the concentrations of 10 ng/μL. This study demonstrated that the alfalfa-derived volatile p-Menth-8-en-2-one, shows significant attraction to thrips, which can be utilized for monitoring and management of odontothrips loti and frankliniella occidentalis.

Plant-derived volatile organic compounds (VOCs) are widely used as insect attractants for population monitoring, offering an efficient and eco-friendly approach to pest management. Since thrips are the dominant pest species in alfalfa fields, this study aimed to identify a suitable attractant trap design that could be employed to monitor Odontothrips loti and Frankliniella occidentalis. The field experiment showed that p-Menth-8-en-2-one, dispensed through PE (Polyethylene) vials positioned at the top of the alfalfa canopy, attracted the most thrips, with the optimal concentrations of 1 µg/µL for O. loti and 50 µg/µL for F. occidentalis, respectively. When both species occur in alfalfa, PVC pipes dispensing p-Menth-8-en-2-one at a concentration of 1 µg/µL provide an effective attractant for both species, offering an indication of presence and relative abundance. Understanding the incidence and abundance of both species in the field provides growers an opportunity to target treatments to protect crops before significant damage occurs, reduce insecticide overuse, and support integrated pest management strategies for these two high-impact pests.