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Dust deposition is considered an important source of many bioavailable nutrients to the marine environment. Nutritional status is the main factor regulating bacterioplankton growth, and thus it is important to study the effects of dust deposition. Microcosm experiments with dust aerosol addition were performed using surface water from the South China Sea (SC) for 12 days and southern Yellow Sea (SY) for 10 days. After incubation, the bacterial biomass in microcosms increased 10.82-fold and 2.22–3.32-fold under dust addition, in SC and SY respectively. Bacterial growth was also stimulated by dust aerosol, indicated by increased and more effcient heterotrophic secondary production. In addition, bacterial community structures were simplified by dust aerosol in both study areas. Alpha- and gamma-proteobacteria were the predominant bacteria in the microcosms following dust addition in SC, whereas alpha- and delta-proteobacteria were the main bacteria in SY. These results demonstrate that dust deposition regulates growth and community structure of marine bacteria in SC and SY by promoting phytoplankton growth.
Arbuscular mycorrhizal fungi (AMF) are widely distributed in grassland ecosystems. However, the diversity and specificity of AMF in the rhizosphere of grassland plants remain largely unexplored. The species and quantitative characteristics of AMF in the rhizosphere soil of 6 common plant species in the Songnen grassland in Northeast China were investigated by using wet sieving and morphological identification methods. The results showed that there were 24 AMF species belonging to 6 genera in the rhizosphere of the 6 plant species. Glomus claroideum and Glomus melanosporum were the common dominant AMF species for most plants. The subdominant species and companion species of the AMF community were different. The diversity index, spore density and infection rate of AMF were significantly different among the rhizosphere of the different plants (p < 0.05). Similarity coefficients of AMF composition varied greatly among plant species. Therefore, the AMF species showed a certain level of host specificity, and this result partially supported the singular hypothesis. Differences in plant species and soil microenvironment were the main reasons explaining the specificity of the AMF in the rhizospheres of grassland plant species.
Climate warming extends insect distribution areas, increases voltinism and makes pest prevention and control more difficult. The MaxEnt ecological niche modeling software was used to simulate Batocera lineolata distribution and predict potential range changes under climate change scenarios. Future B. lineolata distribution was modeled for three climate scenarios (RCP2.6, RCP4.5 and RCP8.5) to predict suitable regions in the 2050s and 2070s. A receiver operating characteristic curve was used to estimate model precision and a jackknife test was used to screen the dominant environmental variables. The results show that the area under the curve of the B. lineolata distribution model could reach an ‘Excellent’ standard. Under current climate conditions, the most suitable region for B. lineolata is 25.5–40.5°N, 102–120°E, distributed discontinuously from south to north and covering an area of 47.17 × 104 km2. For predicted future distribution, except for a decrease in moderately suitable regions under RCP2.6, RCP4.5 and RCP8.5 in the 2050s and RCP2.6 and RCP4.5 in the 2070s, other suitable regions are likely to extend; highly suitable regions would increase continuously. This research provides a theoretical basis to improve pest management strategies regarding B. lineolata to face the challenge of climate change.
The cotton leafhopper, Amrasca biguttula (Ishida), a sucking insect pest of cotton and vegetables, is present throughout Southeast Asia. Patterns of molecular and morphological differentiation among A. biguttula populations collected from seven cotton growing areas of Punjab, Pakistan, were studied by sequencing the barcode region of the mitochondrial cytochrome oxidase subunit 1 (COI) gene and by morphometrically analyzing wing shape. Molecular analysis revealed absence of isolation by distance (r = 0.075, P = 0.341) in spite of significant population differentiation (overall FST = 0.15 ± 0.06 (SE)). Also, haplotype diversity varied between populations, and neutrality tests indicated an excess of rare alleles in one of the seven areas. Although leafhopper populations are clearly shaped by genetic drift and possibly also by founder events, wing shape and size were conserved across the study area. These results have important implications for understanding the processes affecting patterns of molecular and morphological variations of pest insects that often are strongly controlled by agrochemical applications.
Marcela Bernardes Portela, Eliesé Idalino Rodrigues, Carlos Alberto de Sousa Rodrigues de Sousa Rodrigues Filho, Carla Ferreira Rezende, Teógenes Senna de de Oliveira
Ecological corridors are areas of natural vegetation that connect two or more separate habitat patches, surrounded by a non-habitat matrix. Soil fauna is important for sustainability, conservation and soil quality. Thus, in this study, we aimed to investigate the influence of corridors on the soil faunal community in crops near savannah vegetation areas by examining the effects on trophic, movement and taxonomic groups. We collected data during the dry and rainy seasons in two areas of biodynamic agriculture. Then, we calculated trophic, movement, taxonomic group abundance, total abundance, richness, equability and diversity. The taxa Acari, Chilopoda, Oligochaeta, Orthoptera and Psocoptera were the most abundant in cultivated areas with corridors during the rainy season, while the taxa Dermaptera, Diplura, Diptera, Collembola, Formicidae larva, Lepidoptera and Lepidoptera larva were more abundant in cultivated areas with corridors during the dry season. The trophic, movement, taxonomic group abundance, richness, equability and diversity were higher during the rainy season and were not related to corridor presence. Ecological corridors increased the abundance of some taxonomic groups of soil fauna in cultivated areas, thereby contributing to the maintenance of specific taxonomic groups, which provide important ecosystem services.
Wildfire is a pervasive disturbance in the boreal forest, and fire size and severity is increasing due to climate change. Yet, wildfire impacts on boreal bats are unknown. Burned forest may be attractive to bats because of an increase in dead trees and a reduction in vegetative clutter. Using ultrasonic detectors, I sampled little brown bat (Myotis lucifugus) activity at lakeshore and upland sites within burned and mature forest. Activity was greater in mature than burned forest at both upland and lakeshore sites. Activity was greater at lakeshores, where some large snags survived fire. The relative use of edges created by fire, lakeshores and roads was also investigated. Bat activity was greater at lakeshores than other edge types. Bats made little use of burned upland areas or fire-created edges. This study provides a first approximation of the effect of a ‘megafire’ on bats in the boreal forest and suggests that large, severe wildfires may have a negative impact. Protection of mature forest containing large dead trees, particularly along lakeshores, may help to mitigate the loss of habitat due to wildfires. Further work, however, is needed to assess bat activity in burns of differing sizes, severity and age.
Climate change has major effects on background insect herbivory, but only a few studies have involved long-term investigation, and the effects of wind on bigger insect herbivores such as moths have been largely neglected. We correlated climatic data during the period 2006–2017 with a set of background herbivory data of Culcula panterinaria (Bremer et Grey) derived from a long-term investigation (2007–2017) in the oak forest of Luanchuan county, Henan, China and discuss the impacts of wind speed on background insect herbivory. Background insect herbivory was significantly correlated with wind speed parameters of both the same year and previous year, implying direct and cumulative effects of wind speed on background insect herbivory. Our study offers a new perspective for monitoring and predicting background insect herbivory.
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