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Researching the structural characteristics of the spatial correlation network of cultivated land utilization ecological efficiency is of great significance to China's food security and agricultural green and low-carbon development. Taking 47 cities (autonomous prefectures) in the upper reaches of the Yangtze River as the research object, the ecological efficiency of cultivated land utilization from 2010 to 2020 was measured based on the unexpected output model (Super SBM), and the spatial correlation matrix was constructed using the revised gravity model. The structural characteristics of the spatial correlation network were analyzed using the social network model (SNA), and finally, the factors affecting the spatial correlation network of cultivated land utilization ecological efficiency in the upper reaches of the Yangtze River were analyzed through the quadratic assignment procedure (QAP) model. The results show that: (1) the ecological efficiency of cultivated land utilization in the upper reaches of the Yangtze River has been increasing year by year, but the overall level is low, and there is a large gap among provinces. Sichuan Province has the highest average value of 0.605, and Yunnan Province has the lowest average value of 0.359. (2) The ecological efficiency of cultivated land utilization in the upper reaches of the Yangtze River has broken through the provincial boundaries and has formed an obvious spatial correlation network, but the overall density is low, and the network is still relatively loose, needing further development and improvement. Chengdu, Yibin, Luzhou, and other cities are located in the center of the network and have formed four cohesive subgroups. (3)The differences in the level of agricultural economic development, the rural per capita disposable income, the differences in agricultural mechanization intensity, the regional population differences, and spatial adjacency have an impact on the spatial network of ecological efficiency of cultivated land utilization in the upper reaches of the Yangtze River. The difference in the level of agricultural economic development, the rural per capita disposable income, and the differences in agricultural mechanization intensity are negatively correlated, while the regional population differences are positively correlated with spatial adjacency. [ABSTRACT FROM AUTHOR]

The fall armyworm [FAW, Spodoptera frugiperda (J. E. Smith)] is an important invasive pest of maize crops in Africa, Asia and the Middle East. To enable timely and effective pest management, accurate monitoring and forecasting of S. frugiperda populations is essential. In this study, we used food attractants to assess seasonal abundance of S. frugiperda in southern Yunnan (China) and determined adult age based upon ovarian development or testes size. During 2020–2021, the seasonal abundance of trapping S. frugiperda males with food attractants and sex pheromones were approximately the same at two field sites. Both trapping methods yielded S. frugiperda males of different ages—with an identical age structure for both trap types. The proportion of females trapped with food attractants was about 80%, which was significantly higher than that of males. S. frugiperda populations at two field sites were composed of immigrants that either originated in central Yunnan or in eastern Myanmar. Based upon field-level recordings of adult reproductive state, models reliably anticipated S. frugiperda fecundity dynamics. Next, drawing upon meteorological data and FAW adult age, migration trajectories were established for S. frugiperda immigrant populations. Overall, these novel (food-based) monitoring and forecasting tools can improve integrated pest management of S. frugiperda in China and abroad. [ABSTRACT FROM AUTHOR]

Interspecific interactions (e.g., competition, predation) are core determinants of insect population evolution, geographical distribution, trophic dynamics and ecosystem functioning. Following its recent invasion of eastern Asia, the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) co-inhabits maize fields with native lepidopteran herbivores, such as the common cutworm, Spodoptera litura. Here, drawing upon laboratory and field studies, we demonstrate how late-instar S. frugiperda larvae directly prey upon S. litura immature stages and competitively displace them from the maize whorl. Individual maize plants did not mediate the above interactions, with herbivore-damaged leaves not affecting the development rate of either species. In the field, ecological niches of S. frugiperda and S. litura overlapped, with species-specific occupancy rates of whorl-stage leaves (vegetative phase) and ears or tassels (reproductive phase) exceeding 70% and 90%, respectively. Field cage trials showed that S. frugiperda larvae either preyed upon or repelled S. litura larvae from maize plants, routinely resulting in more than 90% mortality of the latter. Field visits and cage studies in Yunnan (SW China) also revealed how—within an approx. 1-year time period—S. frugiperda has become a dominant species in local maize fields and co-infestation of both herbivores on the same plant is rare. Overall, our work shows how the invasive S. frugiperda exhibits a clear competitive advantage over native lepidopterans and could replace certain species within local agroecosystems. This study not only unveils the mechanistic causes of rapid ecological shifts within S. frugiperda-invaded cropping systems, but may also guide subsequent monitoring and management interventions. [ABSTRACT FROM AUTHOR]

[Display omitted] • We assessed physiological determinants of Spodoptera frugiperda migratory flight. • Adult females exhibited strong flight ability during early oviposition phase. • Flight performance was negatively associated with female fecundity. • Over 50% of migratory females were mated and 46–54% had initiated oviposition. • Our work hints at a potential facultative trade-off between flight and reproduction. Since 2016, the fall armyworm (FAW, Spodoptera frugiperda) has invaded large parts of Africa and Asia, impacting millions of hectares of maize crops and thereby posing a major threat to food security. The rapid geographic spread and outbreak dynamics of S. frugiperda are tied to its unique dispersal ability and long-distance migration capability. Yet, up till present, limited research has been conducted on the physiological determinants of S. frugiperda flight and migration. In this study, we used laboratory experiments to assess whether mating and oviposition affect S. frugiperda flight ability and wingbeat frequency. During 2019–2020, migratory FAW females were trapped in Yunnan (China) and dissected to assess ovarian development. Tethered flight assays showed that gravid S. frugiperda females exhibited strong flight ability at 1–3 days following the onset of oviposition. Flight distance and duration negatively correlated with the number of deposited eggs. Ovarian dissections further showed that over 50% of migrant females were mated and 46–54% had initiated oviposition. Our study shows the complex, yet nuanced effects of reproductive status on flight capacity, with possibly a facultative trade-off between flight and reproduction. These novel insights into S. frugiperda physiology and migration behavior can guide future monitoring and integrated pest management (IPM) programs against this newly-invasive pest in China and abroad. [ABSTRACT FROM AUTHOR]