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.
Moderate leaf rolling can maintain leaf erectness, improve light transmittance in the population, and improve light energy utilization, thereby increasing rice yield. This study used ethyl methanesulfonate (EMS) to treat Yunjing 17 (YJ17) and obtained a semi-rolled leaf mutant that was named semi-rolledleaf3 (srl3). We found that the rolled-leaf phenotype was due to the aberrant development of bulliform cells and the loss of sclerenchymatous cells. In addition, the shoot and root length of srl3 seedlings differed from the wild type. The srl3 mutant had significantly lower plant height and seed-setting rate but notably greater tiller number, panicle length, and primary branch number per panicle than the wild type. Genetic analysis showed that a single recessive nuclear gene defined the srl3 mutant, and it was precisely located in a 144-kb region between two insertion-deletion (InDel) markers, M8 and M19, on chromosome 2. In this region, no leaf-rolling-related genes have been reported previously. Thus, the study indicated that SRL3 is a novel leaf-rolling-related gene, and the results laid the foundation for the cloning and functional analysis of the SRL3 gene. 相似文献