The response of plant functional diversity to external disturbances not only effectively predicts changes in the ecosystem but it also reflects how plant communities use external environmental resources.  However, research on how different herbivore assemblages affect plant functional diversity is limited.  Therefore, this study systematically explored the effects of three typical herbivore assemblages (yak grazing, Tibetan sheep grazing, and mixed grazing by yaks and Tibetan sheep) on species richness, plant functional diversity, and soil physicochemical properties in alpine grasslands on the Qinghai-Tibet Plateau, China.  This study further investigated the primary mechanisms driving the changes in plant functional diversity.  The results indicate four key aspects of this system: (1) Grazing significantly enhanced plant functional diversity, particularly when the mixed grazing by yaks and Tibetan sheep was applied at a ratio of 1:2.  This ratio showed the most substantial improvement in the functional dispersion index and Rao’s quadratic entropy index.  (2) Compared to enclosed treatments, grazing increased species richness and β-diversity, contributing to higher plant functional diversity.  (3) Grazing treatments affected various plant traits, such as reducing plant community height and leaf thickness while increasing specific leaf area.  However, the impact on plant functional diversity was most pronounced under the mixed grazing by yaks and Tibetan sheep at a ratio of 1:2.  (4) Species α-diversity was positively correlated with plant functional diversity.  Changes in plant functional diversity were primarily regulated by variations in soil physicochemical properties.  Specifically, increases in soil available nitrogen significantly promoted changes in plant functional diversity, while increases in soil available potassium and bulk density had a significant inhibitory effect on these changes.  Long-term grazing significantly reduced the height of plant communities in alpine meadows, while a balanced mixture of yak and Tibetan sheep grazing, especially at a ratio of 1:2, enhanced plant functional diversity the most.  This suggests that, under these conditions, the use of external environmental resources by the plant community is optimized.

The rice stem borer, Chilo suppressalis (Walker) (Lepidoptera: Crambidae), is one of the most serious pests in rice-growing areas, and it has developed resistance to most insecticides currently used in the field. Cyproflanilide is a novel meta-diamide insecticide that has shown high activities to multiple pests. Evaluating the risk of resistance to cyproflanilide in C. suppressalis is necessary for its preventive resistance management. Here we established the baseline susceptibility of C. suppressalis to cyproflanilide by the rice-seedling dipping method and topical application, and the LC₅₀ and LD₅₀ values were 0.026 mg L^-1 and 0.122 ng/larva, respectively. The LC₅₀ values of cyproflanilide in 37 field populations ranged from 0.012 to 0.061 mg L^-1, and 25 field populations exhibited resistance to chlorantraniliprole with the highest LC₅₀ value of 3770.059 mg L^-1. In addition, a logistic distribution model analysis indicated that only 0.048 mg L^-1 of cyproflanilide was required to kill 90% field chlorantraniliprole-resistant populations of C. suppressalis, compared to 2087.764 mg L^-1 of chlorantraniliprole for a similar level of control. Resistance screening over 19 generations did not result in resistance to cyproflanilide (RR=3.1-fold). The realized heritability (h²) of resistance was estimated as 0.067 by using threshold trait analysis, suggesting a low risk of cyproflanilide resistance development in susceptible strains. The Cypro-SEL population (F₁₀) had no obvious fitness cost (relative fitness=0.96), and no significant changes in sensitivity to seven tested insecticides. These findings suggested that cyproflanilide is a promising insecticide for the management of chlorantraniliprole-resistant C. suppressalis. Moreover, this integrated risk assessment provides scientific application guidelines for the sustainable resistance management of cyproflanilide for controlling C. suppressalis.