Abstract Background The black soldier fly (BSF, Hermetia illucens L.) is one of the most promising insects for bioconversion of organic waste, which often carry a high microbial load with potential foodborne pathogens. Although horizontal transmission (from rearing substrate to larvae) has been extensively studied, less is known about vertical transmission of microorganisms, and particularly of foodborne pathogens, across different BSF life stages. Results This study investigated the microbial dynamics and vertical transmission of Escherichia coli across different life stages (larvae, prepupae, pupae and adults) of one BSF life cycle and its associated substrate (chicken feed) and frass, based on a combination of general microbial counts (based on culture-dependent techniques) and the bacterial community composition (based on 16S rRNA gene sequencing). Multiple interactions between the microbiota of the substrate, frass and BSF larvae were affirmed. The larvae showed relative consistency among both the microbial counts and bacterial community composition. Diversification of the bacterial communities started during the pupal stage, while most notable changes of the microbial counts and bacterial community compositions occurred during metamorphosis to adults. Furthermore, vertical transmission of E. coli was investigated after substrate inoculation with approximately 7.0 log cfu/g of kanamycin-resistant E. coli , and monitoring E. coli counts from larval to adult stage. Although the frass still contained substantial levels of E. coli (&gt; 4.5 log cfu/g) and E. coli was taken up by the larvae, limited vertical transmission of E. coli was observed with a decreasing trend until the prepupal stage. E. coli counts were below the detection limit (1.0 log cfu/g) for all BSF samples from the end of the pupal stage and the adult stage. Additionally, substrate inoculation of E. coli did not have a substantial impact on the bacterial community composition of the substrate, frass or different BSF life stages. Conclusions The fluctuating microbial counts and bacterial community composition underscored the dynamic character of the microbiota of BSF life stages. Additionally, vertical transmission throughout one BSF life cycle was not observed for E. coli . Hence, these findings paved the way for future case studies on vertical transmission of foodborne pathogens across consecutive BSF life stages or other insect species. 

Microbial dynamics and vertical transmission of Escherichia coli across consecutive life stages of the black soldier fly (Hermetia illucens).

Intensive land degradation occurs under conditions of accelerated urbanization; it is strongly associated with the loss of soil natural capital, primarily animals, plant cover, and biological diversity in general. The creation and functioning of parks, in particular green spaces, in the urbanized areas is an effective mechanism for optimizing the ecological situation within the cities and preventing desertification. The soils of parks are an integral component of green infrastructure; they determine the conditions for the growth and development of both individual plants and green spaces as a whole. The soil buffering capacity actively participates in the mechanisms of implementation of the development and stabilization of soil fertility potentials. The buffering capacity determines the proportion of the soil potential that controls the processes of immobilization (deposition) and mobilization (release, loss) of a particular element of fertility: first of all, mineral nutrients for plant growth, productive moisture, thermal energy in soil, gas composition of soil air, and acidity. We collected soil samples beneath the crowns of trees growing in the territory of the Taras Shevchenko Central Culture and Leisure Park, as one of the largest parks in the city of Dnipro (Ukraine). The soil samples were collected in order to assess the soil acid-base (pH) buffering capacity (pHBC) and determine the direction of microbiological processes in urban soils of the park area afforested with stands from such introduced tree species as green ash (Fraxinus pennsylvanica), black locust (Robinia pseudoacacia), northern red oak (Quercus rubra), tree of heaven (Ailanthus altissima), Kentucky coffee tree (Gymnocladus dioica), and box elder (Acer negundo). The acid-base buffering capacity of the urban soil was determined using the Arrhenius method and estimated according to the buffering area within the acid-base range, calculated using the Simpson formula. Direction of microbial processes in the soil was determined according to the indexes of mineralization-immobilization, pedotrophicity, and oligotrophicity. The output was processed using statistical methods (arithmetic mean and standard deviation were calculated; the difference in the means was found according to the Tukey’s comparison test; interdependencies were determined by linear correlation). We have found significant, strong positive correlations between the pH level of urban soils in the rhizosphere area of the introduced species of park dendroflora and the buffering area within the acid and acid-base (total) range of external influence, as well as a strong negative correlation between pH and buffering area in the alkaline range of external influence. We identified weak mineralization signs according to the ratio of functional groups of microbiota in the studied sites forested with Fraxinus pennsylvanica and Acer negundo. 

pdf/environmental-quality-assessment-of-soil-as-a-component-of-4x2f7fr1q8.pdf

Environmental quality assessment of soil as a component of green spaces in parks of the megalopolis

The Fossil Record of Chondrichthyans from the Cretaceous-Eocene in Chile: Diversity and Paleobiogeographic Implications

Additional file 1: Table S1. Microbial counts of the substrate, frass and different BSF life stages, reared on the control substrate (chicken feed). Results are presented as the mean of 6 replicates (n = 3 cycle repetitions x 2 technical repetitions) ± standard deviation. 

Additional file 1 of Microbial dynamics and vertical transmission of Escherichia coli across consecutive life stages of the black soldier fly (Hermetia illucens)

Land degradation poses a serious challenge to food security, livelihood sustainability, ecosystem services and biodiversity conservation, while inefficient land management leads to widespread loss of soil biodiversity. The soil buffer capacity is actively involved in the mechanisms of implementing such an ecosystem service as the development and stabilization of soil fertility. Buffering determines the share of the soil potential that determines the processes of immobilization (deposition) and mobilization (release, loss) of a particular element of fertility – first of all, mineral nutrients required by plants, productive moisture, thermal energy of the soil, gas composition of soil air, acidity. The soils in parks on the territory of megacities are an integral component of them determining the conditions for the growth and development of green spaces. We assessed the acid-base (pH) buffer capacity of urban areas in a park area covered with tree stands of such introduced tree species as horse chestnut (Aesculus hippocastanum), sugar maple (Acer saccharum), small-leaved elm (Ulmus parvifolia), common hackberry (Celtis occidentalis), honey locust (Gleditsia triacanthos) and Japanese pagoda tree (Styphnolobium japonicum) growing on the territory of the T. G. Shevchenko Park (Dnipro city, Ukraine). Soil samples were collected under the crowns of these tree species. The acid-base buffering capacity of urban soils was determined by the Arrhenius method, which includes adding certain volumes of acid and alkaline components to the sample, and further calculating the buffering area within acid and base intervals. Buffering areas were calculated using the Simpson formula. The results were processed with statistical methods (arithmetic mean and standard deviation were calculated, and the difference in means was found according to the Tukey's comparison test). Initially the samples of the studied soils were found to have mostly a slightly alkaline reaction of the soil solution. Within the acid range of external influences, the buffer capacity of urban soils under introduced tree species was determined to establish the following descending series: horse chestnut, common hackberry, small-leaved elm, honey locust, Japanese pagoda tree, sugar maple. The same series was established for the total acid-base buffering capacity. The results show the greater acid-base buffer capacity of soils sampled under horse chestnut, common hackberry, small-leaved elm and honey locust trees, and therefore these soils were resistant to degradation compared to the soils sampled under Japanese pagoda tree and sweet maple. The environment-forming role of introduced tree species in the implementation of buffer properties of urban soils in the park on the megalopolis territory can be assumed.

Assessment of the soil buffer capacity in the green plantings of the megalopolis parks

The article evaluates the dependence of the most common indices of species diversity on sample size and determines their ability to differentiate between different types of ecosystems, with a special emphasis on discriminating between natural and anthropogenic ecosystems. An approach to adjusting the indices to reduce their dependence on sample size was also proposed. The study was conducted in seven types of ecosystems: four were natural and three were anthropogenically transformed. Samples of soil animals were selected in 2011–2013 and 2021 using the same methods. A total of 20,518 soil animal specimens belonging to 202 species were collected in all study locations. The null alternative was generated by randomly selecting samples containing 2, 3, ..., 110 soil animals from the combined soil animal sample. For each gradation of sample size, 200 sample variants were formed. The density of soil macrofauna in natural ecosystems ranged from 3.6 ± 1.5 to 15.2 ± 6.9 specimens per sample, and in artificial ecosystems – from 13.2 ± 7.6 to 21.0 ± 11.9 specimens per sample. The number of species ranged from 22–80 species, and in artificial ecosystems it was 38–99 species. Indicators of species diversity correlated with each other. A high level of correlation was observed between indicators within groups of indices: indices of species richness and indices of heterogeneity and evenness. Fisher’s log-series alpha and the fundamental parameter of biodiversity were highly correlated with each other, as well as with the Margalef, species richness, and Chao’s species abundance indices. The log-normal distribution best describes the dominance patterns in terms of abundance in the natural ecosystems, and the Zipf-Mandelbrot distribution best describes the dominance patterns in terms of abundance in the artificial ecosystems. Diversity indices were ordered in the space of two dimensions, one explaining the variation between ecosystems and the other depending on sample size. The ordering of the traditional indices showed that there is a vacancy for the best index in the sense that such an index should best explain differences between ecosystems and differences between natural and artificial ecosystems. It should also be independent of sample size. The Simpson heterogeneity index and the Simpson evenness index were the best of the traditional indices, but they did not explain differences between ecosystems very well, especially when it came to distinguishing between natural and artificial ecosystems. The Margalef index, which is supposed to be independent of sample size, on the other hand, showed a very high level of dependence. Such a dependence was also found for the Menhinick index, though to a lesser extent. Obviously, size dependence negatively affects the differential ability of the indices. The corrected indices of species richness and the Shannon index are practically independent of sample size and have a greater ability to differentiate ecosystems by the level of diversity, with natural ecosystems characterized by consistently higher values of the corrected indices than artificial ecosystems. The dependence on the sample size makes indices from different ecosystems practically incomparable, which makes their use meaningless. Even minor differences in sample size can lead to significant deviations in the values of diversity indices. The application of the Michaelis-Menten model allowed us to suggest a method of correction of species richness indices and the Shannon index. After the correction, the indices are practically independent of the sample size, and their differential ability to characterize individual ecosystems and the level of anthropogenic transformation increases significantly. 

Diversity of diversity indices: Which diversity measure is better?

Parks perform a wide range of ecosystem services in urban environments. The functional importance of parks depends on the composition and structure of the tree stand and the specific influence on soil and microclimatic conditions. The article reveals the dependence of soil and microclimatic properties on the structure of the crown space of a park stand. Spectral indices were also shown to be applicable for predicting the spatial variability of soil and climatic properties and indicators of crown space. Soil properties (temperature, moisture, and electrical conductivity in the 5–7 cm layer) and microclimatic parameters (light exposure, air temperature, and atmospheric humidity) were measured in the park plantation using a quasi-regular grid. The canopy structure and gap light transmission indices were extracted from the true-colour fisheye photographs. Thirty species of trees and shrubs were detected in the stand and understory. Robinia pseudoacacia L. was found most frequently (24.5% of all tree records). Acer negundo L. and A. platanoides L. were also frequent (12.4% and 15.5%, respectively). The first four principal components, whose eigenvalues exceeded unity, were extracted by the principal components analysis of the variability of ecological properties and vegetation indices. The principal component 1 explained 50.5% of the variation of the traits and positively correlated with the spectral vegetation indices. The principal component 1 reflected the variability of tree cover densities due to the edaphic trophicity. The principal component 2 described 13% of the variation in the feature space. This component correlated positively with the spectral indices. The principal component 2 was interpreted as a trend of vegetation cover variability induced by moisture variation. The principal component 3 described 8.6% of trait variation. It was most strongly correlated with the atmospheric humidity. An increase in atmospheric humidity was associated with an increase in the soil moisture and electrical conductivity and a decrease in the soil and atmospheric temperature. The principal component 4 described 7.5 % of the variation of traits. An increase in the values of principal component 4 was associated with an increase in the soil moisture and electrical conductivity and atmospheric moisture and was associated with a decrease in the soil and atmospheric temperature. The combinations of the trophotope and hygrotope create the optimal conditions for specific tree species, which is a condition for achieving the maximization of ecosystem services. The mineral nutrition conditions of plants and soil moisture exhibit spatial patterns that allow them to be considered in the design and management of park plantations. The ecological indices measured in the field were shown to be predicted using the vegetation indices. Multiple regression models were able to explain 11–61% of indicator variation. The regression relationships between markers of soil and microclimatic conditions and vegetation predictors are important for monitoring the condition of park plantations and evaluating the performance of park plantation management tools.

Modeling the spatial variation of urban park ecological properties using remote sensing data

The use of black locust (Robinia pseudoacacia L.) is still controversial, especially in managed forests, due to its invasive nature. The black locust has been proven effective in reclamation of degraded lands when native species are not an alternative in the face of the climate change and desertification. Therefore, the importance of black locust in European ecosystems remains a matter of debate. Of course, it is an adventitious species originating from another continent. However, the ecological characteristics of the species in its natural range are very useful for ensuring the restoration of vegetation cover in areas that have experienced significant anthropogenic pressure. This species has a large number of important and useful features that make it an important agent in the forestry system and provide significant environmental and economic benefits. The status of black locust as an invasive species, i.e. one that is capable of uncontrolled spread, remains speculative. Such a conclusion requires various studies, including those identifying exact age of the plants based on morphometric parameters. In our study, we tested the hypothesis that plant height and trunk diameter will allow for an accurate assessment of black locust age. The plants of black locust were measured in the zone of spontaneous self-seeding of plants from a planted 60-years-old forest. The plants dispersed towards a fallow land, formed in the corner of an agricultural field. The spreading began 15 to 20 years ago. The plants are mainly propagated by seedlings. An expert estimated the age of the plants visually. The measured trees were cut to obtain cross sections to account for the number of annual rings. A total of 68 trees were examined for morphometric characters. Black locust communities during self-dispersal are represented by individuals of different ages. The spatial pattern of distribution of individuals of different ages can reveal the spatial and temporal dynamics of the formation of spontaneous populations of black locust. For this purpose, it is critical to accurately identify the age of a large sample. Expert estimation of age is fast and fairly accurate, but it depends greatly on the qualifications of the expert and oftentimes plant ages are underestimated, especially in the early stages of population development. Plant height is also a good predictor of plant age, but the model gives poor predictions for plants older than 10 years. The tree height ranged 2.3 to 16.0 meters. The diameter at breast height (DBH) ranged 1.0 to 17.5 cm. The diameter at the root collar (DRC) ranged 1.6 to 21.7 cm. The age of the studied trees, determined by the number of annual rings per transect, ranged 6 to 17 years. The age of the trees according to the expert estimates was 8.2 ± 4.8 years. The expert estimates of age and the age according to the number of annual rings were statistically significantly different. The expert estimates of tree age were linearly related to tree size, while estimates of the number of annual rings showed a logarithmic relationship with tree height. Expert estimates also showed a closer relationship with tree height, while the relationship of estimates based on the number of annual rings had a slightly lower dependence on the morphometric traits. Regression analysis showed that there is a linear relationship between morphometric traits of the black locust. The coefficient of determination for the dependence of diameter at breast height on tree height was 0.96, and for the dependence of diameter at the base of the trunk on diameter at breast height was 0.97. This indicates a high level of multicollinearity of these morphometric traits when considering them as predictors of plant age. Taking into account the diameter at breast height and the diameter at the level of the root collar significantly improved the predictive ability of the model for identifying the age of the black locust trees. 

Age estimation of black locust (Robinia pseudoacacia) based on morphometric traits

Selection of sources of heat resistance in the cultivated species Solanum andigenum Juz. et Buk

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Diversity of diversity indices: Which diversity measure is better?

Modeling the spatial variation of urban park ecological properties using remote sensing data

Age estimation of black locust (Robinia pseudoacacia) based on morphometric traits

Selection of sources of heat resistance in the cultivated species Solanum andigenum Juz. et Buk