Insect resistance responses of ten Aster varieties to damage by Tephritis angustipennis in the three rivers source region of China

Aster varieties are widely used for medicinal purposes, landscaping, and ecological restoration, but their growth and reproduction are significantly threatened by the seed predator Tephritis angustipennis (Diptera: Tephritidae). The cultivation of pest-resistant varieties offers an effective, economical, and eco-friendly approach to managing T. angustipennis infestations. This study evaluates the impact of T. angustipennis on ten Aster varieties in the Three Rivers Source Region (TRSR), with a focus on population density, plant damage rate, and the activity of resistance enzymes and insect-resistant metabolites. The results classified the ten varieties into four resistance groups: one highly resistant variety [HR: Aster altaicus (MQAA)], four moderately resistant varieties [MR: Aster asteroides (DRAA), Aster flaccidus (QLAF), Aster tongolensis (BMAT), Aster poliothamnus (MQAP)], two moderately susceptible varieties [MS: Aster diplostephioides (QLAD), Aster souliei (DRAS)], and three highly susceptible varieties [HS: A. diplostephioides (MQAD), Aster yunnanensis var. labrangensis (MQAY), Aster farreri (MQAF)]. Notably, HR and MR varieties exhibited significantly higher activities of catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), trypsin inhibitor (TI), and chymotrypsin inhibitor (CI), as well as higher contents of tannins (TN) and flavonoids (FN), compared to MS and HS varieties. Specifically, the HR variety (MQAA) showed the highest levels of CAT, POD, SOD, and TN, significantly enhancing its resistance to T. angustipennis. Statistical analyses further revealed that MDA, TN, FN, and antioxidant enzyme activities were found to be key factors influencing insect resistance across the different varieties and resistance levels. These findings enhance our understanding of the physiological and biochemical mechanisms underlying resistance in Aster spp. and offer valuable insights for developing integrated pest management strategies. By identifying and promoting resistant varieties, this study lays the groundwork for effective, sustainable control measures that protect Aster crops from T. angustipennis damage.