Effects of fertilization on soil ecological stoichiometry and fruit quality in Karst pitaya orchard.

Pitaya (Hylocereus undulatus) is a significant cash crop in the karst region of Southwest China. Ecological stoichiometry is an essential method to research biogeochemical cycles and limiting elements. The purpose of this study was to explore the stoichiometric characteristics of C, N, and P in Karst pitaya orchards and fruit quality and to elucidate the mechanism and process of nutrient cycling. The results showed that: (1) Fruit quality was highest under the combination of chemical and organic fertilizers. Compared to the control, the contents of per-fruit weight, vitamin C, and soluble sugar increased significantly by 55.5%, 60.7%, and 23.0%, respectively, while the content of titratable acidity decreased significantly by 22.0%. (2) The content of soil nutrients under fertilization stress showed a downward trend in general, as did microbial biomass and extracellular enzyme activities. (3) Different fertilization treatments significantly affected the soil-microbial stoichiometry C:N ratio, C:P ratio, with research areas being significantly limited by C and P. (4) Spearman and PLS-SEM (partial least squares-structural equation model) analysis results showed that under the influence of fertilization, there was a significant positive effect between microorganisms and soil nutrients, but a significant negative effect between soil nutrients and quality. The results of this study offer an innovative perspective on pitaya quality research in Karst areas.

Fruit surface temperature data at different ripeness stages and ambient temperature provided as temperature-annotated 3D point clouds of apple trees.

By means of a unique, low vibration circular conveyor system, plant sensors capturing light detection and ranging (LiDAR) unit and thermal camera were moved on the same route, around blocks of apple trees, with seven Malus x domestica Borkh. 'Gala' apple trees in each block. Measurements took place four times during the season. Additionally at harvest, diurnal courses were recorded with 18 readings during three days. The data are provided as [i] raw data (3D point clouds of 3 blocks of trees scanned from right and left sides and thermal images), [ii] processed 3D point clouds of canopies annotated with temperature data from the thermal camera, and [iii] manually segmented 3D point clouds of fruit, representing the spatially-resolved fruit surface temperature (FST). Manual FST readings are provided on each measuring date and during diurnal courses. The fruit data are capturing 1236 FST, providing temperature distribution as 3D point cloud and one manually recorded reference FST per fruit. Additionally, fruit size and colour were measured for each fruit, despite for the first date, when fruit were too small for colour readings. Weather data are provided from a station located in the orchard. Usage of data could be (a) in developing methodology for 3D point cloud processing based on raw data, accomplished with reference FST data. Furthermore, (b) the pre-processed point clouds of fruit surface temperature can be reused in ecophysiological studies related to global warming, optimizing fruit production systems, and other. Because the sensors and trees were measured from the same angle and distance, time series analysis of the canopies would be possible.

A Detection Algorithm for Citrus Huanglongbing Disease Based on an Improved YOLOv8n.

Given the severe impact of Citrus Huanglongbing on orchard production, accurate detection of the disease is crucial in orchard management. In the natural environments, due to factors such as varying light intensities, mutual occlusion of citrus leaves, the extremely small size of Huanglongbing leaves, and the high similarity between Huanglongbing and other citrus diseases, there remains an issue of low detection accuracy when using existing mainstream object detection models for the detection of citrus Huanglongbing. To address this issue, we propose YOLO-EAF (You Only Look Once-Efficient Asymptotic Fusion), an improved model based on YOLOv8n. Firstly, the Efficient Multi-Scale Attention Module with cross-spatial learning (EMA) is integrated into the backbone feature extraction network to enhance the feature extraction and integration capabilities of the model. Secondly, the adaptive spatial feature fusion (ASFF) module is used to enhance the feature fusion ability of different levels of the model so as to improve the generalization ability of the model. Finally, the focal and efficient intersection over union (Focal-EIOU) is utilized as the loss function, which accelerates the convergence process of the model and improves the regression precision and robustness of the model. In order to verify the performance of the YOLO-EAF method, we tested it on the self-built citrus Huanglongbing image dataset. The experimental results showed that YOLO-EAF achieved an 8.4% higher precision than YOLOv8n on the self-built dataset, reaching 82.7%. The F1-score increased by 3.33% to 77.83%, and the mAP (0.5) increased by 3.3% to 84.7%. Through experimental comparisons, the YOLO-EAF model proposed in this paper offers a new technical route for the monitoring and management of Huanglongbing in smart orange orchards.

Osmia lignaria (Hymenoptera: Megachilidae) increase pollination of Washington sweet cherry and pear crops.

Apis mellifera Linnaeus (Hymenoptera: Apis), honey bees, are the most widely used managed crop pollinators. However, their high rental cost and uncertain availability for North American orchard crops have motivated growers to explore alternative pollination options. We examined whether adding solitary, spring-flying Osmia lignaria Say (Hymenoptera: Megachilidae), blue orchard bees, as co-pollinators with A. mellifera in Washington sweet cherry and pear orchards enhances fruit set and yield compared to the use of A. mellifera alone. We added managed O. lignaria to orchard sites where A. mellifera hives were already present. Fruit set, fruit yield, and O. lignaria reproduction at O. lignaria-supplemented sites were compared to nearby, paired sites pollinated only by A. mellifera (3 paired cherry and 3 paired pear sites). For both crops, the addition of O. lignaria significantly increased fruit set but did not yield at harvest. Microscopic inspection of pollen grains from O. lignaria nest cell provisions confirmed that O. lignaria primarily visited orchard flowers. Mean retention of O. lignaria in cherry orchards was slightly higher (65%) than O. lignaria retention reported in other orchard crops (30%-60%). However, retention in pear orchards was much lower (≤20%). These results show that supplementing hives with O. lignaria in Washington spring orchard crops can increase overall pollination, but that trees fail to bear developing fruit to maturity. The strategy of using co-pollinators, O. lignaria and A. mellifera, in US orchards may act as "pollination insurance" when A. mellifera hives are in low supply or when the weather is not amenable for A. mellifera flight during the bloom period.

[Effect of Partial Substitution of Chemical Fertilizers with Organic Fertilizers on N2O and NO Emissions from a Peach Orchard].

Organic fertilizer substitution has been promoted as a weight loss, efficient, and diversified fertilizer substitution technology in agricultural production. However, there is a lack of comprehensive assessment of the impact of organic fertilizers on N2O and NO emissions from orchards. In this study, N2O and NO emissions from peach orchards were observed annually using static dark box-gas chromatography to compare the effects of chemical fertilizer application alone and partial replacement of chemical fertilizer treatment on NO emissions from peach orchards. The results showed that the partial replacement of chemical fertilizers with organic fertilizers reduced the total N2O and NO emissions from peach orchards by 15.0 % and 9.4 %, respectively. The N2O and NO emission factors were reduced by 21.3 % and 21.1 %. The mineral N content of the soil in the organic fertilizer treatment was lower than that in the chemical fertilizer treatment alone. The organic fertilizer treatment increased the contribution of AOA to nitrification and decreased the contribution of AOB, thus reducing N2O and NO from nitrification. In addition, the results of the dual isotope mixing model[δ18O(N2O/H2O) vs. δ15NSP] indicated that the bacterial denitrification/nitrifying bacterial denitrification (bD/nD) process served as the primary pathway for N2O emissions in peach orchards. Partial substitution with organic fertilizers enhanced soil denitrification, resulting in larger reductions in the amounts of N2O and NO. Therefore, partial substitution of organic fertilizer is a viable measure to mitigate nitrogen oxide emissions from orchards and to achieve green and low-carbon development in agriculture.

[A Pilot Test of Olive Weevil Repellents in an Olive Orchard].

Recently, feeding damage by the olive weevil Pimelocerus (Dyscerus) perforatus Roelofs, which utilizes olive trees (Olea europaea Linne) as a host plant, has become the biggest obstacle to olive cultivation in Japan. We previously identified several volatile plant-derived natural products that exhibit repellent activity against olive weevils. In this study, we conducted a pilot test of repellents in an olive orchard along with the use of insecticide. During three consecutive years from 2021 to 2023, the first year was the observation period, and the second and third years were set aside for a trial period for o-vanillin and geraniol as repellents, respectively. Using o-vanillin, the number of adult olive weevil outbreaks decreased to almost half a year in the experimental area, the use of geraniol then resulted in a drastic reduction of the number of individual olive weevils in the experimental area. In contrast, adults and larvae outbreaks increased in the control area without a repellent, despite the use of insecticide. These results indicate that the volatile repellents drove the olive weevils away and kept them at bay in the field. Based on the observations, we will be able to provide a new approach for the control of olive cultivation, including fruit and leaves used for commercial purposes, following integrated pest management (IPM) practices, such as reducing environmental poisoning from intense insecticides, and returning olive weevils to their original habitat outside of olive orchards.

Improving path planning for mobile robots in complex orchard environments: the continuous bidirectional Quick-RRT* algorithm.

Efficient obstacle-avoidance path planning is critical for orchards with numerous irregular obstacles. This paper presents a continuous bidirectional Quick-RRT* (CBQ-RRT*) algorithm based on the bidirectional RRT (Bi-RRT) and Quick-RRT* algorithms and proposes an expansion cost function that evaluates path smoothness and length to overcome the limitations of the Quick-RRT* algorithm for non-holonomic mobile robot applications. To improve the zigzag between dual trees caused by the dual-tree expansion of the Bi-RRT algorithm, CBQ-RRT* proposes the CreateConnectNode optimization method, which effectively solves the path smoothness problem at the junction of dual trees. Simulations conducted on the ROS platform showed that the CBQ-RRT* outperformed the unidirectional Quick-RRT* in terms of efficiency for various orchard layouts and terrain conditions. Compared to Bi-RRT*, CBQ-RRT* reduced the average path length and maximum heading angle by 8.5% and 21.7%, respectively. In addition, field tests confirmed the superior performance of the CBQ-RRT*, as evidenced by an average maximum path lateral error of 0.334 m, a significant improvement over Bi-RRT* and Quick-RRT*. These improvements demonstrate the effectiveness of the CBQ-RRT* in complex orchard environments.

Canopy Architectural Characteristics of Ten New Olive (Olea europaea L.) Genotypes and Their Potential for Cultivation in Super-High-Density Orchards.

In recent years, there has been growing interest in olive genotypes (Olea europaea L.) suitable for super-high-density (SHD > 1200 trees/hectare) orchards. To date, only a few cultivars are considered fitting for such cultivation system. In this study, the first results on the architectural characteristics of the canopy of ten new olive genotypes are presented. Their suitability for SHD orchards was evaluated and compared with the cultivar 'Arbequina', which is considered suitable for SHD olive orchards and, for this reason, was used as the control. Several canopy measurements were taken, and some architectural parameters, such as branching frequency, branching density, and branch diameter/stem diameter ratio were calculated. The branching frequency value was greater than 0.20 in 'Arbequina' and in only four of the genotypes. The branching density in five genotypes was similar to 'Arbequina'. 'Arbequina' had the lowest value for the branch diameter/stem diameter ratio, and only three genotypes had similar values. These initial results showed that only one genotype has all canopy architectural characteristics comparable to those of the cv. 'Arbequina'. Further studies are needed to evaluate the production traits of these new genotypes and complete their characterization.

Isolation and Characterization of a Lytic Bacteriophage RH-42-1 of Erwinia amylovora from Orchard Soil in China.

Fire blight, caused by the bacterium Erwinia amylovora, is a major threat to pear production worldwide. Bacteriophages, viruses that infect bacteria, are a promising alternative to antibiotics for controlling fire blight. In this study, we isolated a novel bacteriophage, RH-42-1, from Xinjiang, China. We characterized its biological properties, including host range, plaque morphology, infection dynamics, stability, and sensitivity to various chemicals. RH-42-1 infected several E. amylovora strains but not all. It produced clear, uniform plaques and exhibited optimal infectivity at a multiplicity of infection (MOI) of 1, reaching a high titer of 9.6 × 109 plaque-forming units (PFU)/mL. The bacteriophage had a short latent period (10 min), a burst size of 207 PFU/cell, and followed a sigmoidal one-step growth curve. It was stable at temperatures up to 60 °C but declined rapidly at higher temperatures. RH-42-1 remained viable within a pH range of 5 to 9 and was sensitive to extreme pH values. The bacteriophage demonstrates sustained activity upon exposure to ultraviolet radiation for 60 min, albeit with a marginal reduction. In our assays, it exhibited a certain level of resistance to 5% chloroform (CHCl3), 5% isopropanol (C3H8O), and 3% hydrogen peroxide (H2O2), which had little effect on its activity, whereas it showed sensitivity to 75% ethanol (C2H5OH). Electron microscopy revealed that RH-42-1 has a tadpole-shaped morphology. Its genome size is 14,942 bp with a GC content of 48.19%. Based on these characteristics, RH-42-1 was identified as a member of the Tectiviridae family, Alphatectivirus genus. This is the first report of a bacteriophage in this genus with activity against E. amylovora.

Assessment of pesticide exposure to applicators during spraying in orchards with a stretcher-mounted sprayer.

Various health risk assessment models have been developed to evaluate occupational pesticide exposure in China. However, there has been limited investigation into the relationship between health risks and pesticide spraying in orchards. In this study, we analyzed pesticide exposure of applicators while spraying with a stretcher-mounted sprayer in orchards located in four different climatic regions. All garments' unit exposure (UE) demonstrated a right-skewed distribution, with gloves and shins accounting for the highest proportion of dermal pesticide exposure. We observed little difference in dermal and inhalation UE levels between apple and citrus orchards, except for pesticide exposure levels on wipes and faces. While 57% of the inhalation UE distribution variance was attributed to clustering and location effects, no significant differences were observed in dermal exposure levels. We evaluated the impact of different levels of protective clothing on pesticide exposure levels, according to applicators' working habits in China. Our findings revealed that improved levels of protection significantly reduced dermal exposure to pesticides, particularly when wearing gloves during spraying with a stretcher-mounted sprayer. Based on our empirical data, we utilized a simple random sampling model and an intercept-only lognormal mixed model to estimate dermal and inhalation exposure levels. The estimated dermal UE was accurate to within 3-fold with 95% confidence, and half of the estimated inhalation UE was acceptable according to the fold relative accuracy (fRA). Our established and verified statistics for dermal and inhalation UE can be utilized to evaluate the potential pesticide exposure to applicators during spraying in orchards with a stretcher-mounted sprayer.

Evaluating the use of unmanned aerial vehicles for spray applications in mountain Nanguo pear orchards.

BACKGROUND: Nanguo pear is a distinctive pear variety in northeast China, grown mainly in mountainous areas. Due to terrain limitations, ground-based pesticide application equipment is difficult to use. This limitation could be overcome by using unmanned aerial vehicles (UAVs) for pesticide application in Nanguo pear orchards. This study evaluated the spraying performance of two UAVs in the Nanguo pear orchards and compared them with a manually used backpack electric sprayer (BES). The study also analyzed the effect of canopy size on droplet deposition and ground loss, and evaluated two sampling methods, leaf sampling and telescopic rod sampling. RESULTS: Compared to BESs, droplet deposition is lower for UAVs, but the actual pesticide active ingredient deposition is not necessarily lower given the solution concentration. The droplet deposition varies among different UAVs due to structural differences. Under the same UAV operating parameters, droplet deposition on trees with smaller canopy sizes is typically greater than that on trees with larger canopy sizes, and the ground loss was also more severe. Although telescopic rod sampling is a quick and convenient method, it can only reflect the trend of droplet deposition, and the data error is greater compared with leaf sampling. CONCLUSION: UAVs can achieve better droplet deposition in mountainous Nanguo pear orchards and does almost no harm to the operators compared with the BES. However, canopy size needs to be considered to adjust the application volume rate. Telescopic rods can be used for qualitative analyses, but are not recommended for quantitative analyses. © 2024 Society of Chemical Industry.

Green manure incorporation enhanced soil labile phosphorus and fruit tree growth.

Introduction: The incorporation of green manures substantially enhances the conversion of external phosphorus (P) fertilizers and soil-reserved P into forms readily available to plants. The study aims to evaluate the influence of green manure additions on soil phosphorus dynamics and citrus growth, considering different green manure species and initial soil phosphorus levels. Additionally, the research seeks to elucidate the microbiological mechanisms underlying the observed effects. Methods: A citrus pot experiment was conducted under both P-surplus (1.50 g·P·kg-1) and P-deficient (0.17 g·P·kg-1) soils with incorporating legume (Leg), non-legume (Non-Leg) or no green manure residues (CK), and 18O-P labeled KH2PO4 (0.5 g, containing 80‰ δ18Op) was additionally introduced to trace the turnover characteristics of chemical P fertilizer mediated by soil microorganisms. Results and discussion: In P-surplus soil, compared with the CK treatment, the Leg treatment significantly increased soil H2O-Pi (13.6%), NaHCO3-Po (8.9%), NaOH-Pi (9.5%) and NaOH-Po (30.0%) content. It also promoted rapid turnover of P sources into H2O-Pi and NaHCO3-Pi pools by enhancing the phoC (576.6%) gene abundance. In contrast, the Non-Leg treatment significantly augmented soil H2O-Pi (9.2%) and NaHCO3-Po (8.5%) content, facilitating the turnover of P sources into NaHCO3-Pi pools. Under P-deficient soil conditions, compared with the CK treatment, the Leg treatment notably raised soil H2O-Pi (150.0%), NaHCO3-Pi (66.3%), NaHCO3-Po (34.8%) and NaOH-Pi (59.0%) content, contributing to the transfer of P sources into NaHCO3-Pi and NaOH-Pi pools. This effect was achieved through elevated ALP (33.8%) and ACP (12.9%) activities and increased pqqC (48.1%), phoC (42.9%), phoD (21.7%), and bpp (27.4%) gene abundances. The Non-Leg treatment, on the other hand, led to significant increases in soil NaHCO3-Pi (299.0%) and NaHCO3-Po (132.6%) content, thereby facilitating the turnover of P sources into NaHCO3-Pi and NaOH-Pi pools, except for the phoC gene abundance. Both Leg and Non-Leg treatments significantly improved citrus growth (7.3-20.0%) and P uptake (15.4-42.1%) in P-deficient soil but yielded no substantial effects in P-surplus soil. In summary, introducing green manure crops, particularly legume green manure, emerges as a valuable approach to enhance soil P availability and foster fruit tree growth in orchard production.

Targeting optimal power consumption: Optimizing operational parameters for orchard furrowing and fertilizing machine.

In response to the problem of excessive power consumption during the furrowing operation of orchard furrowing fertilizer machines, an optimization experiment of furrowing operation parameters for orchard furrowing fertilizer machine was conducted based on discrete element simulations. This research focused on the impact of furrowing device operation parameters on furrowing power consumption under full machine operating conditions. Firstly, a kinematics analysis of the soil granules during cutting was done. The mathematical model of soil granules through three movement processes of rising, detachment, and falling was established to determine the main factors affecting the power consumption of furrowing. Secondly, in assessing the furrowing power consumption, the stability coefficient of the furrowing depth, and the percentage of soil cover, alongside the key parameters of furrowing depth, forward propulsion velocity, and furrowing blade rotation speed, a comprehensive quadratic orthogonal rotation regression experiment was meticulously conducted. It was established that test metrics and test parameters regress. Finally, the test parameters were comprehensively optimized after analyzing each factor's impact on the test metrics. The orchard furrowing fertilizer machine's optimal operating parameters were determined, and the verification test was performed. According to the field test findings, the forward propulsion velocity was 785 m/h, and the furrowing blade rotation speed was 190 r/min when the furrowing depth was 275 mm. At this point, the furrowing power consumption was 2.39 kW, the soil cover percentage was 69.06%, and the furrowing depth stability coefficient was 95.08%. These results were in line with the requirements of orchard furrowing operation. The findings of the study can be utilized as a guide for structural changes to orchard furrowing equipment and the management of furrowing operation parameters.

Development of Location-Data-Based Orchard Passage Map Generation Method.

Currently, pest control work using speed sprayers results in increasing numbers of safety accidents such as worker pesticide poisoning and rollover of vehicles during work. To address this, there is growing interest in autonomous driving technology for speed sprayers. To commercialize and rapidly expand the use of self-driving speed sprayers, an economically efficient self-driving speed sprayer using a minimum number of sensors is essential. This study developed an orchard passage map using location data acquired from positioning sensors to generate autonomous driving paths, without installing additional sensors. The method for creating the orchard passage map presented in this study was to create paths using location data obtained by manually driving the speed sprayer and merging them. In addition, to apply the orchard passage map when operating autonomously, a method is introduced for generating an autonomous driving path for the work start point movement path, work path, and return point movement path.

Occurrence and distribution of trisiloxane ethoxylates in citrus orchard soils in China: Analytical challenges.

Trisiloxane ethoxylates (TSEOn) are widely used as agricultural surfactants due to their significant synergism with the active ingredients of pesticides, generally, including three typical end groups which are hydroxyl (TSEOn-H), methoxy (TSEOn-CH3), and acetoxy (TSEOn-COCH3), respectively. However, the potential ecotoxicological and endocrine-disrupting risks of TSEOn congeners have recently attracted ever-growing concern. Above all, there is limited research on the concentration levels of TSEOn in agroecosystems. This study, simultaneous analysis of 39 TSEOn oligomers in citrus orchard soils in China was implemented by the modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The method detection limits (MDLs) and the method quantification limits (MQLs) for TSEOn were 0.003-0.07 µg/kg and 0.01-0.20 µg/kg, respectively. The recoveries for TSEOn oligomers in soils ranged from 81 % âˆ¼ 106 % with related standard deviations (RSDs) < 7 %. This newly developed UPLC-MS/MS method with high sensitivity and stability allows us to successfully trace the occurrence of TSEOn congeners in the citrus orchard soils from 3 provinces and 1 municipality in China. The detected concentrations of TSEOn-H oligomers in the sampled soils ranged from 0.02 to 0.288 µg/kg (dry weight). The congener profiles of TSEOn-H were dominated by TSEOn-H (n = 6- 8) in the soils. Additionally, the total concentrations of TSEOn-H congeners (ΣTSEOn-H) in the soils were in the range of 0.03 to 1.49 µg/kg. A comparison of ΣTSEOn-H distribution among the different citrus orchard soils indicated a higher level of ΣTSEOn-H in the soil samples collected from Zhejiang Province. Notably, TSEOn-CH3 or TSEOn-COCH3 oligomers were not detected in the tested soils. To the best of our knowledge, this is the first report on the occurrence and distribution of TSEOn congeners in agricultural soils.

LeGO-LOAM-FN: An Improved Simultaneous Localization and Mapping Method Fusing LeGO-LOAM, Faster_GICP and NDT in Complex Orchard Environments.

To solve the problem of cumulative errors when robots build maps in complex orchard environments due to their large scene size, similar features, and unstable motion, this study proposes a loopback registration algorithm based on the fusion of Faster Generalized Iterative Closest Point (Faster_GICP) and Normal Distributions Transform (NDT). First, the algorithm creates a K-Dimensional tree (KD-Tree) structure to eliminate the dynamic obstacle point clouds. Then, the method uses a two-step point filter to reduce the number of feature points of the current frame used for matching and the number of data used for optimization. It also calculates the matching degree of normal distribution probability by meshing the point cloud, and optimizes the precision registration using the Hessian matrix method. In the complex orchard environment with multiple loopback events, the root mean square error and standard deviation of the trajectory of the LeGO-LOAM-FN algorithm are 0.45 m and 0.26 m which are 67% and 73% higher than those of the loopback registration algorithm in the Lightweight and Ground-Optimized LiDAR Odometry and Mapping on Variable Terrain (LeGO-LOAM), respectively. The study proves that this method effectively reduces the influence of the cumulative error, and provides technical support for intelligent operation in the orchard environment.

Bioaccumulation of Metals in Some Auchenorrhyncha (Insecta: Hemiptera) Species in Cherry Orchards Near Motorway and Their Usage as Biomonitor for Metal Pollution.

Traffic borne pollutants negatively affect organisms. This study aimed to determine the impact of traffic pollution on Auchenorrhyncha species and their usage as biomonitor for metal pollution. The study was carried out in the cherry orchard near the Amasya-Samsun D100/E80 motorway in Amasya, Türkiye. Metal concentrations in specimens tended to decrease with the increasing distance from the motorway. Significant variations were determined in some metal concentrations based on distance from the motorway. The maximum and minimum metal concentrations were obtained from 0 to 100 m, respectively. Negative relationships were determined between distance from the motorway and Cd, Co, Cr, Cu, Fe, Mn, Ni and Pb concentrations in Arboridia versuta (Melichar, 1897), and Cd, Co, Cr, Cu, Ni and Pb concentrations in Psammotettix provincialis (Ribaut, 1925). Metals were accumulated in the body of specimens. Therefore, it is thought that Auchenorrhyncha species may be used as a biomonitor for metal pollution due to their high metal concentrations.

Systemic pesticides in a solitary bee pollen food store affect larval development and increase pupal mortality.

Solitary bees are often exposed to various pesticides applied for pest control on farmland while providing pollination services to food crops. Increasing evidence suggests that sublethal toxicity of agricultural pesticides affects solitary bees differently than the social bees used to determine regulatory thresholds, such as honey bees and bumblebees. Studies on solitary bees are challenging because of the difficulties in obtaining large numbers of eggs or young larvae for bioassays. Here we show the toxic and sublethal developmental effects of four widely used plant systemic pesticides on the Japanese orchard bee (Osmia cornifrons). Pollen food stores of this solitary bee were treated with different concentrations of three insecticides (acetamiprid, flonicamid, and sulfoxaflor) and a fungicide (dodine). Eggs were transplanted to the treated pollen and larvae were allowed to feed on the pollen stores after egg hatch. The effects of chronic ingestion of contaminated pollen were measured until adult eclosion. This year-long study revealed that chronic exposure to all tested pesticides delayed larval development and lowered larval and adult body weights. Additionally, exposure to the systemic fungicide resulted in abnormal larval defecation and increased mortality at the pupal stage, indicating potential risk to bees from fungicide exposure. These findings demonstrate potential threats to solitary bees from systemic insecticides and fungicides and will help in making policy decisions to mitigate these effects.

A Fixed-Parameter Tractable Algorithm for Finding Agreement Cherry-Reduced Subnetworks in Level-1 Orchard Networks.

Phylogenetic networks are increasingly being considered better suited to represent the complexity of the evolutionary relationships between species. One class of phylogenetic networks that have received a lot of attention recently is the class of orchard networks, which is composed of networks that can be reduced to a single leaf using cherry reductions. Cherry reductions, also called cherry-picking operations, remove either a leaf of a simple cherry (sibling leaves sharing a parent) or a reticulate edge of a reticulate cherry (two leaves whose parents are connected by a reticulate edge). In this article, we present a fixed-parameter tractable algorithm to solve the problem of finding a maximum agreement cherry-reduced subnetwork (MACRS) between two rooted binary level-1 networks. This is the first exact algorithm proposed to solve the MACRS problem. As proven in an earlier work, there is a direct relationship between finding an MACRS and calculating a distance based on cherry operations. As a result, the proposed algorithm also provides a distance that can be used for the comparison of level-1 networks.

Combined role of ground cover management in altering orchard surface‒subsurface erosion and associated carbon-nitrogen-phosphorus loss.

The combined role of ground cover management in controlling soil erosion and nutrient loss from new orchards is still less understood. In this study, four ground cover management practices, orchard with grass cover (OG), orchard with interplant cover (OI), orchard with straw cover (OS), and orchard with bare ground (OB), were designed to identify their impacts on soil erosion and associated carbon-nitrogen-phosphorus loss in new orchards by rainfall simulation tests with rainfall intensities of 60, 90, and 120 mm h-1 and 90 min rainfall duration. The results showed that OS had the lowest surface flow coefficient (6.6%) and highest subsurface flow coefficient (32.5%). The highest soil loss rate occurred in the OB plot (65.4 g m-2 min-1), and the lowest soil loss rate occurred in the OS plot (0.5 g m-2 min-1). OS plot showed better effectiveness in improving soil erosion. However, the increased infiltration capacity was facilitated in terms of causing non-point source pollution. The C-N-P ratios of surface flow in different cover measures (OB, OI, OG, and OS) were 1.4:1.2:0.9:1, 1.8:1.7:1.2:1, and 2.3:1.9:1.2:1, respectively. The ratios of sediment in different cover measures were 7.3:9:2.3:1, 2:1.5:1.2:1, and 1.2:1:0.8:0.7, respectively. Cover management plots play an active role in reducing nutrient loss in surface flow and sediment, but the increased infiltration in covered management plots is associated with the risk of groundwater contamination in subsurface flow. The C-N-P ratios of subsurface flow in OB and covered managed plots (OI, OG, and OS) were 1:3.3:1.6:2.7, 1:1.5:2.2:2.4 and 1:1.2:1.5:1.3, respectively. Therefore, when managing the phenomenon of soil erosion through ground cover measures, attention should also be focused on the function of cover measures in regulating non-point source pollution underground, such as subsurface flow. This research recommends a combination of cover management measures to further mitigate erosion and the risk of groundwater contamination.