Maximum Feeding Research Articles

Biological Parameters and Feeding Potential of Micromus timidus Hagen (Neuroptera: Hemerobiidae) on Selected Aphid Species

In the present study, we investigated on the developmental biology, adult longevity and fecundity of Micromus timidus Hagen on Aphis craccivora (Koch), Aphis gossypii Glover, Rhopalosiphum maidis (Fitch) and Uroleucon compositae (Theobald) at room temperature (28±20C) and relative humidity of 70%. The study design followed was completely randomized design (CRD). The study was conducted with three replications with 10 larvae in each replication for biology studies and for adult parameters 3 replications with 10 pairs in each replication used. Shortest incubation period, II instar and III instar duration, total larval period, pre-pupal period, and egg to adult period of M. timidus were recorded on A. craccivora, shortest I instar duration was recorded on U. compositae and least pupal period on A. gossypii. The developmental periods for all trait were extended when fed on R. maidis. The reproductive traits viz., oviposition period and adult longevity (male and female) were maximum when M. timidus adults fed on A. gossypii, and the highest fecundity was recorded when fed on A. craccivora. Feeding potential in M. timidus increases progressively across successive instars, with III instar larvae exhibiting the highest aphid predation rate, and first instar larvae displaying the lowest feeding activity. The maximum feeding potential of the larva was noted on A. craccivora (142.47 ± 31.66), while, the adult feeding potential increased when it was given with A. gossypii (1335.10 ± 192.74).

Application Of Microbubble Technology To Increase Oxygen Content In The Aquaculture Of Tambaqui (Colossoma Macropomum)

The oxygen consumed is used to oxidize food substances to produce energy. Therefore, the metabolic rate is usually indicated by the rate of oxygen consumption per time unit. In most intensive aquaculture systems, oxygen content is widely used due to the high stocking density and maximum feeding rates. This study aimed to evaluate the growth performance of freshwater pomfret (Colossoma macropomum) treated with increased oxygen in two different systems. The study was conducted in a laboratory scale by applying T-test data analysis. The difference of treatment level applied in the comparison of aeration and microbubble consists of two treatments and three replications. The researcher used commercial floating pellets PF0 with 25% protein content, the feeding rate was 5% of the biomass. The feed was given daily during the culture for two times a day. Data of the study were analyzed using T-test on the Statistical Product and Service Solutions (SPSS) software Version 17.0. Results of the study showed that aeration system using microbubble resulted in dissolved oxygen (DO) of 6.5 ± 0.17, 100% pomfret fish survival rate (SR), Survival Growth Rate (SGR) of 1.83 ± 0.24, Feed Conversion Ratio (FCR) of 1.37 ± 0.17, Protein Efficiency Ratio (PER) of 2.79 ± 0.37, Feed Utilization Efficiency (FUE) of 0.67 ± 0.09, Absolute Weight Growth of 52.02 ± 1.60; it was better than using aeration. This study has developed a model of freshwater pomfret fish aquaculture to provide growth value.

Assessing biological invasion predatory impacts through interaction strengths and morphological trophic profiling

AbstractBiological invasions are a major stressor on ecosystems worldwide, but tools to predict their predatory impact remain limited. Here, we quantified invader impacts using two complementary approaches: functional responses (to reveal per capita and multiple predator interaction strengths) and ecomorphology (to reveal trophic profiles and competitive overlap). We compared Mozambique tilapia Oreochromis mossambicus, a native southern African cichlid, and a near-trophically analogous invasive congener, the Nile tilapia Oreochromis niloticus. Both Nile tilapia and Mozambique tilapia exhibited a potentially prey population destabilizing Type II functional response. In both single and multiple predator pairings, invasive Nile tilapia had significantly greater prey consumption rates than native Mozambique tilapia, and thereby a greater predatory impact than its native congeneric. Attack rates were greater for Nile tilapia than Mozambique tilapia, with both species showing more similar handling times and maximum feeding rates. No evidence for multiple predator effects was detected within or between these species, and therefore impacts of both species increased additively in the presence of conspecific or heterospecific competitors. Morphological trait analyses found general differences between these two species, with the invasive Nile tilapia having distinctively larger lower jaw closing force, gill resistance and gill raker length, which facilitated greater feeding capacities over the native species. Trophic profiles predicted using morphological trait differences showed high dietary overlap and served as evidence for potential exploitative competition between the two species. These results reveal superior interaction strengths and ecomorphological trait profiles of an invasive over native species which could influence impact and native species replacement dynamics. Novel applications of functional response and ecomorphology provide complementary insights into predatory and competitive impacts from invasive species, aiding impact prediction across environmental contexts.

Functional response metrics explain and predict high but differing ecological impacts of juvenile and adult lionfish.

Recent accumulation of evidence across taxa indicates that the ecological impacts of invasive alien species are predictable from their functional response (FR; e.g. the maximum feeding rate) and functional response ratio (FRR; the FR attack rate divided by handling time). Here, we experimentally derive these metrics to predict the ecological impacts of both juvenile and adult lionfish (Pterois volitans), one of the world's most damaging invaders, across representative and likely future prey types. Potentially prey-population destabilizing Type II FRs were exhibited by both life stages of lionfish towards four prey species: Artemia salina, Gammarus oceanicus, Palaemonetes varians and Nephrops norvegicus. FR magnitudes revealed ontogenetic shifts in lionfish impacts where juvenile lionfish displayed similar if not higher consumption rates than adult lionfish towards prey, apart from N. norvegicus, where adult consumption rate was considerably higher. Additionally, lionfish FRR values were very substantially higher than mean FRR values across known damaging invasive taxa. Thus, both life stages of lionfish are predicted to contribute to differing but high ecological impacts across prey communities, including commercially important species. With lionfish invasion ranges currently expanding across multiple regions globally, efforts to reduce lionfish numbers and population size structure, with provision of prey refugia through habitat complexity, might curtail their impacts. Nevertheless, the present study indicates that management programmes to support early detection and complete eradication of lionfish individuals when discovered in new regions are advised.

Evaluation of feeding table optimizations in Pacific white shrimp nursery biofloc systems

A 45-day experiment was conducted to optimize feeding rates in the nursery phase of Pacific white shrimp reared in biofloc systems (BFT). Four treatments were evaluated in quadruplicate, according to the Van Wyk table: maximum feeding rate; minimum feeding rate; minimum feeding rate minus 10%; and maximum feeding rate plus 10%. Post-larvae (0.08 ± 0.00 g) were cultured at the density of 2,000 shrimp·m-3, and water quality, solids production, and productive performance were all monitored. No significant difference was observed in final mean weight (1.47 ± 0.17 g), productivity (2.34 ± 0.20 kg·m-3) and survival (85.29 ± 5.44%) among treatments, but feed conversion ratio was significantly lower in the minimum feeding rate and minimum feeding rate minus 10% treatments, indicating efficient feed conversion without compromising growth. These treatments also resulted in lower values of toxic nitrogen compounds and total suspended solids, suggesting a positive impact on water quality. Although these rates proved suitable, continuous adjustments are needed owing to variations in the BFT system. This study provides guidelines for optimizing feeding management in superintensive BFT nursery systems.

Effects of lactose content in milk replacer on apparent digestibility, growth, liver mRNA expression, and blood parameters related to metabolism of dairy calves

Even with the same energy supply, differences in energy sources may affect calf growth and metabolism. In this study, we evaluated the effects of feeding 3 different milk replacers (MRs) with different lactose supplies under isoenergetic conditions on calf digestibility, growth, and metabolism-related markers. Fifteen Holstein bull calves were randomly assigned to one of 3 MR-feeding treatments: low-lactose (L:38%), medium-lactose (M:41%), or high-lactose (H:46%). After birth, calves were provided colostrum and treatment MRs were fed from 1 d of age and gradually increased to a maximum feeding rate at 20 d of age (L:1.16 kg/d, M:1.21 kg/d, H:1.26 kg/d DM) without feeding solid feeds during the experimental period. Blood samples were temporarily collected weekly to assess blood concentrations of metabolites and hormones. From 30 to 36 d of age, the calves were euthanized and liver samples were collected to determine growth-related mRNA expression. L calves showed a greater body length than H calves and the highest GHR mRNA expression. Plasma concentrations of total cholesterol, urea nitrogen, total protein, albumin, insulin, and insulin-growth factor-1 were not different, but plasma concentrations of triglycerides were higher in order H, M, and L. These results showed that the difference in lactose content in the MR affected calf metabolism, and the L-MR was suggested to be more likely to enhance growth into the peripheral tissues.

Field and laboratory microplastics uptake by a freshwater shrimp.

Microplastics are widespread pollutants, but few studies have linked field prevalence in organisms to laboratory uptakes. Aquatic filter feeders may be particularly susceptible to microplastic uptake, with the potential for trophic transfer to higher levels, including humans. Here, we surveyed microplastics from a model freshwater shrimp, common caraidina (Caridina nilotica) inhabiting the Crocodile River in South Africa to better understand microplastic uptake rates per individual. We then use functional response analysis (feeding rate as a function of resource density) to quantify uptake rates by shrimps in the laboratory. We found that microplastics were widespread in C. nilotica, with no significant differences in microplastic abundances among sampled sites under varying land uses, with an average abundance of 6.2 particles per individual. The vast majority of microplastics found was fibres (86.1%). Shrimp microplastic accumulation patterns were slightly higher in the laboratory than the field, where shrimp exhibited a hyperbolic Type II functional response model under varying exposure concentrations. Maximum feeding rates of 20 particles were found over a 6 h feeding period, and uptake evidenced at even the lowest laboratory concentrations (~10 particles per mL). These results highlight that microplastic uptake is widespread in field populations and partly density dependent, with field concentrations corroborating uptake rates recorded in the laboratory. Further research is required to elucidate trophic transfer from these taxa and to understand potential physiological impacts.

Study on the Effect of Electrolytes on Processing Efficiency and Accuracy of Titanium Alloy Utilizing Laser and Shaped Tube Electrochemical Machining.

Electrochemical machining (ECM) has become more prevalent in titanium alloy processing. However, the presence of the passivation layer on the titanium alloys significantly impacts the performance of ECM. In an attempt to overcome the passivation effects, a high-temperature electrolyte or the addition of halogen ions to the electrolyte has been used. Still, it often results in compromised machining accuracy and surface roughness. This study applied laser and shaped tube electrolytic machining (Laser-STEM) for titanium alloy drilling, where the laser was guided to the machining zone via total internal reflection. The performance of Laser-STEM using different types of electrolytes was compared. Further, the effects of laser power and pulse voltage on the machining side gap, material removal rate (MRR), and surface roughness were experimentally studied while drilling small holes in titanium alloy. The results indicated that the use of passivating electrolytes improved the machining precision, while the MRR decreased with an increase in laser power during Laser-STEM. The MRR showed an increase while using aggressive electrolytes; however, at the same time, the machining precision deteriorated with the increase in laser power. Particularly, the maximum feeding rate of 6.0 mm/min for the tool electrode was achieved using NaCl solution as the electrolyte during Laser-STEM, marking a 100% increase compared to the rate without the use of a laser. Moreover, the model and equivalent circuits were also established to illustrate the material removal mechanisms of Laser-STEM in different electrolytes. Lastly, the processing of deep small holes with a diameter of 1.5 mm, a depth of 38 mm, and a surface roughness of Ra 2 µm was achieved via Laser-STEM without the presence of a recast layer and heat-affected zones. In addition, the cross-inner flow channels in the titanium alloys were effectively processed.

Size-dependent functional response of the round goby Neogobius melanostomus; implications for more accurate impact potential calculation

Abundance and per-capita foraging efficiency are essential factors for predicting and quantifying an invasive predator impact on prey, i.e., the impact potential (IP). However, population structure is not included in the calculation, and IP accuracy might be improved by incorporating predator body size. The population structure of the round goby Neogobius melanostomus, a highly invasive predator, was surveyed in the Elbe River. We determined the functional response (FR, per capita foraging) of the three most abundant size classes of N. melanostomus on the water louse Asellus aquaticus. We then calculated the IP for each size class and for the entire population with (the actual impact potential – IPA) and without (the impact potential for limit size rage – IPLSR) population body size structure (based on FR of the medium size class). All three size classes of the predator showed type II FR with respect to A. aquaticus. The estimated FR parameters, attack rate and handling time, as well as the maximum feeding rate, were size dependent. Despite the lowest per capita foraging efficiency, small individuals displayed the highest IP among the tested size classes because of their high abundance. Conversely, medium and large individuals, although showing highest per capita foraging efficiency, displayed lower IP. Hence, IPA showed more precise IP calculations compared to IPLSR. Overestimation of the potential impact as a consequence of omitting predator population size structure was negligible at the investigated locality. The IP of the N. melanostomus population five years post-invasion can be accurately calculated based on the FR of medium-sized fish.

FUN Azores: a FUNctional trait database for the meio-, macro-, and megafauna from the Azores Marine Park (Mid-Atlantic Ridge)

Trait-based approaches that complement taxonomy-based studies have increased in popularity among the scientific community over the last decades. The collection of biological and ecological characteristics of species (i.e., traits) provides insight into species and ecosystem vulnerability to environmental and anthropogenic changes, as well as ecosystem functioning. Here, we present the FUN Azores trait database, describe our approach, evaluate its scope, compare it to other marine trait databases, and explore the spatial distribution of its traits with “functional maps.” While most of the available trait databases to date contain essential information to understand the functional diversity of a taxonomic or functional group, our ecosystem-based approach provides a comprehensive assessment of diverse fauna (i.e., meio-, macro-, and megafauna) from benthic and pelagic environments in the Azores Marine Park; including ridges, seamounts, hydrothermal vents, and the overlying water column. We used a collaborative approach involving 30 researchers with different expertise to develop the FUN Azores database, which contains compiled data on 14 traits representing morphological, behavioral, and life history characteristics for 1,210 species across 10 phyla. The “functional maps” show a distinct distribution of the two most common size classes, suggesting different communities with different functionalities. The following traits had the best scoring coverage (i.e., >95% of the species scored): maximum body size, body form, skeleton material, feeding structure, motility, environmental position, substratum affinity, distribution, and depth range; while traits related to species behavior (e.g., sociability or aggregation tendencies) and life history (e.g., developmental mechanism) had lower scoring coverage, highlighting the need for further research to fill these knowledge gaps. We found a larger number of species in the benthic compared to the pelagic environment and differing species composition between areas within the Azores Marine Park resulting from varying biodiversity, ecosystem types, sampling effort, and methodologies used. The FUN Azores database will foster and facilitate trait-based approaches in the area, develop a framework for expansion of cross-ecosystem and cross-taxa trait databases elsewhere, and improve our ecological understanding of the Azores Marine Park and its conservation requirements.

Current temperatures limit the potential impact of a commonly traded predatory gastropod

The pet trade has facilitated the spread of invasive alien species (IAS) globally, with negative consequences for biodiversity. The prediction of impacts is a major goal for invasion ecologists, and is especially crucial in an industry often lacking knowledge about traded species. We focused on the predatory gastropod Anentome helena, a species originating in south-east Asia and traded around the world, but with taxonomic uncertainty. We first set out to determine where our study organism fell within the A. “helena” species complex, known to comprise at least four cryptic species, before assessing the effect of temperature on the number of prey, the pulmonate snail Physella acuta, killed per predator via functional response experiments at two temperatures. We used 22 °C as a recommended temperature for housing the species in captivity, and 18 °C as a representative summer lake temperature in temperate climates of Europe. We also assessed the role of predator group size (1×, 2×, 3×) on predation (total consumption and average per capita consumption) at the experimental temperatures with fixed densities of prey, as well as the effect of these temperatures on prey activity. Our organisms belonged to a cryptic species originating from Thailand (Anentome sp. A), matching the findings of aquarium trade samples in other continents. In the functional response experiments, we found maximum feeding rate to be significantly reduced at the lower temperature. A similar result ensued from group feeding, with total consumption significantly reduced and the reduction in average per capita consumption approaching significance at the lower temperature. There was no significant effect of group size on the average per capita consumption in the group trial, indicating neutral conspecific interactions. No significant effect of temperature on the activity of the prey species was found, suggesting decreased consumption was mainly driven by predator, rather than prey. These results suggest limited A. helena impacts in the short-term, but increasing temperatures with climate change may facilitate greater consequences from releases. We suggest future studies assess other potential predatory impacts and survival across relevant abiotic conditions, and encourage the use of similar methods to assess the impacts of other commonly traded species.

Thermal Effects on Ecological Traits of Salmonids

Here, I review thermal influences on metabolic rates and aerobic scope; growth; adult body size; and reproductive and behavioural traits, such as tendency and timing of the migration of salmonid fishes. A thermal window bounded by the upper and lower incipient lethal temperatures (UILT and LILT) determines where salmonids can survive. For most salmonids, LILT is close to 0 and UILT is between 20 and 30 °C. UILT and LILT are influenced by the acclimation temperature. Thermal tolerance is affected by fish size and ambient oxygen content, which decreases with increasing temperature. Standard metabolic rate (SMR), the energy required to maintain essential functions, increases with temperature, whereas maximum metabolic rate (MMR) increases with temperature until reaching a peak (pejus). Then, it decreases gradually to zero, i.e., the upper critical limit (TCrit). Aerobic scope (AS = MMR-SMR) reaches its maximum at the pejus temperature. Metabolic rates and aerobic scope can be modified by temperatures that the fish experiences during embryogenesis and possibly also as larvae and young fry. At maximum feeding, maximum growth increases to a point at or below the pejus temperature. The optimum temperature for growth decreases with reduced food intake and increased body size. As for metabolic rate, the growth rate is influenced by the temperature during embryonic development. In a warmer climate, adult body size is expected to decrease chiefly because of a younger age at maturity. Parental fish retained at a higher temperature during maturation produce larger eggs, and this change in egg size may also be transferred to next-generation offspring. Furthermore, embryogenesis in warmer water leads to larger gonad and egg sizes at maturity. Water temperature influences locomotion, foraging and migratory activity. In a warmer climate, juveniles migrate to the sea earlier in spring. In addition, higher embryo temperature leads to delayed return of adult salmon from the ocean. Thus, temperature affects life history traits of salmonid fishes, partly as a direct effect on metabolic rates and food consumption and partly induced as a phenotypically plastic effect. The phenotypically plastic response may preadapt offspring to perform better in the expected future thermal environment.

Modelling and optimising process of micro-plasma arc freeform fabrication

The main factors limiting the development of wire-based additive manufacturing (w-AM) are deposition process instability and deposition deviation caused by side feed. In this paper, the device tuning accuracy is introduced into the wire-arc deposition model for the first time, a wire-arc stable deposition model in micro-plasma arc directional energy deposition (mPA-DED) was established, and the process of the wire from contacting the micro-plasma arc (mPA) column to conducting stable metal transfer was carefully analyzed. A sensitivity coefficient describing the link between wire size and device adjustment precision in mPA-DED is proposed. The link between the sensitivity coefficient and the maximum meltable wire feeding speed and the threshold value of the maximum stable deposition speed was quantitatively analyzed, and the model was verified by cross-comparison experiments among the design wire size, arc size, and wire-arc position deviation. A well-formed 40-layer curved metal sample with a material area utilization ratio of 90.54 % was steadily deposited by using the proposed model and the optimized deposition parameters. This study offers theoretical guidance for designing an online control system for the deposition process to improve the stability of the fabrication process and deposition accuracy in micro-plasma arc freeform fabrication.

АГРОБІОЛОГІЧНЕ ОБГРУНТУВАННЯ СІВАЛКИ ТОЧНОГО ВИСІВУ ЗЕРНОВИХ КУЛЬТУР

Abstract The purpose of research. To substantiate the agrotechnical requirements for the seeder for accurate (uniform in depth and placement on the area) sowing for grain ear crops of the continuous row method of sowing. The optimal area for plant nutrition and the depth of wrapping winter wheat seeds were determined. Research methods. A field method – to determine the interaction of the object of research with the elements of technology: depth of seed wrapping and feeding area; calculated and weighted – determining the yield of winter wheat. Results. The best conditions for realizing the biological ability of winter wheat plants of the Tobak variety to form the highest grain productivity were during sowing according to the scheme of 7х7 cm and a feeding area of 49 cm2. The yield increase compared to the control (row method of sowing with 15 cm between rows) is 1.05 t/ha, or 13.1%. On the variant with a feeding area of 36 cm2 with a 6х6 cm sowing scheme, the grain yield decreased by 0.15 t/ha, compared to the 7x7 cm scheme. On these two most productive variants, the sowing rate was only 130 kg/ha and 97 kg, respectively /Ha. It is important to note that even with the maximum feeding area (10x10 cm), where only 45 kg/ha of seeds (1.0 million/ha) were sown, the yield remained high and amounted to 7.40 t/ha. In the experiment to study the depth of sowing, the highest yield of the RZHT Reform variety of winter wheat was formed on variants with a 2 cm and 3 cm depth of wrapping, respectively 8.22 t/ha and 8.30 t/ha. Deepening of the seeds by 4 cm led to a yield decreasing by 0.22 t/ha. For sowing to a 5 cm depth the yield was decreased by 0.43 t/ha. Increasing of the sowing depth to 6 cm and 7 cm significantly reduced the yield. Conclusions. The need for uniform placement of seeds on the area and depth requires the creation of a seeder with precise sowing of grain crops seeds of continuous row method of sowing. However, precision sowing has no proper biological and technological grounds. As a result of the research, the optimal parameters of the area of winter wheat plant nutrition (6x6 cm and 7x7 cm) and the depth of seed sowing (2-3 cm) were substantiated. It was concluded that the application of the appropriate technology for growing grain crops with the use of precision seed drills will allow to reduce seed sowing rates by half and increase the field productivity of grain. Key words: winter wheat, feeding area, sowing depth, precision seed drill.

Handling- or digestion-limited predators: the role of body mass and habitat complexity in predator functional response

The predator functional response quantifies the per capita feeding rate of predators as a function of prey density and is a key element of feeding interactions. Variations in its parameters are strongly associated with interaction strength and population dynamics. We examined 18 functional responses within marine whelk-bivalve systems, varying predator body size, prey species, and habitat structure. Our findings suggest that the marine whelk Rapana venosa is handling-limited, a predator type that has received less attention in previous research. We propose further categorizing handling-limited predators into 2 types: pursuit-limited (where maximum feeding rate could be influenced by habitat complexity) and ingestion-limited (where maximum feeding rate is impacted not by habitat complexity, but by predator-prey body mass ratios and prey defense strategy). We found that handling time scales negatively with predator-prey body mass ratios, but this trend exhibits layers of complexity. We propose that the transition from handling to digestion limitation with increasing predator-prey body mass ratios underlies this trend. Our study also confirms the importance of prey types, in addition to known effects of body mass ratios and habitat structure. In summary, our study reveals that simple assumptions about body masses and prey defense strategy may usefully refine estimates of feeding interactions in complex food webs.

Electrochemical milling of deep-narrow slots with a pulsating electrolyte flow field

Deep-narrow slots (DNSs) (width<4 mm and depth/width>2 mm) are inherent features in die-casting molds as heat-dissipating slots and turbomachinery components for seal slots. Electrochemical milling (EC-milling) is a flexible method to machine variety of structures by controlling the tool path. The process employs a tubular tool with a flat end face through which the electrolyte is supplied coaxially. However, owing to the small inter-electrode gap (IEG), the quantity and velocity of electrolyte flowing into the IEG are weakened during machining of DNSs. This reduces the machining quality and efficiency. Therefore, this paper proposes a method of EC-milling of DNSs with a pulsating flow field. A tubular tool with a wedge-shaped end face (WS-tube) is designed, and both the quantity and velocity of electrolyte flowing into the IEG will be changed with the rotation of WS-tube. Thus, a pulsating flow field is generated which can enhance the mass transport in the IEG. Consequently, both the machining efficiency and quality are improved. Flow-field simulation results indicate that as compared with the traditional flat end face tube (F-tube), WS-tube can generate a periodic pulsating flow field in both front and side IEG, and the peak electrolyte flowing velocity is also increased. The experiment results reveal that compared to that of 0.24 mm/min with F-tube, the maximum feeding speed reaches to 0.42 mm/min with WS-tube, and both the surface quality and taper are improved at the same time. Increasing the rotation speed of tube tool and pulse frequency further enhances the transport of electrolytic by-products, and the machining quality is improved. With the optimized parameters, a 5 mm deep DNS with width of 1.48 mm ± 0.02 mm, taper of 1.44° ± 0.27° and the surface roughness (Ra) of 0.7 µm has been successfully fabricated. • Pulsating flow field was proposed for electrochemical milling of deep-narrow slot. • A tube tool with wedge-shaped end face was designed to generate pulsating flow field. • With the rotation of wedge-shaped tube tool, pulsating flow field was generated in both front and side inter-electrode gap. • Both the machining quality and feeding speed of DNS were improved with pulsating flow field.

Prediction of Growth Characteristics and Migration Period of Spodoptera frugiperda (Lepidoptera: Noctuidae) According to Temperature.

Simple SummarySpodoptera frugiperda is a pest with a wide host range that causes severe damage to the agricultural sector around the world. The species, which was first recorded in South Korea in 2019, has been affecting corn farmers by harming the leaves and fruits. Unfortunately, measures to initially respond to the species have not been implemented appropriately due to the lack of information on the growth characteristics of S. frugiperda in the Korean climate. Against this backdrop, we analyzed the growth characteristics and degree of damage to corn leaves at different temperatures and found that the optimal temperature for the growth of S. frugiperda was in the range 28–32 °C, which is the temperature range during summer in Korea. It is most active during this season, affecting more number of farmers progressively. In this regard, more efforts are needed to control the pest in summer in Korea.In 2019, an outbreak of Spodoptera frugiperda (Smith) was first reported in Korea. This study aimed to determine the growth rate and feeding amount of S. frugiperda by temperature to establish the right time window for its control and management. Linear regression analysis was used to determine the growth period and thermal requirements of S. frugiperda. The longest growth period of 97.2 ± 1.2 days was observed at 16 °C, and the shortest growth period of 15.5 ± 0.7 days was observed at 36 °C. In terms of each growth stage, the pupal period was the longest at all temperatures, followed by the egg period. The maximum corn leaf feeding amount (6.61 g) was observed for the larvae grown at 16 °C, and the minimum (2.9 g) was observed at 36 °C. However, the daily feeding amount of S. frugiperda larvae was the highest at 28 °C and 32 °C. The hatching rate according to temperature exceeded 70% at 24 °C, 28 °C, and 32 °C, and the survival rate of larvae and pupae was 100% at 24 °C to 32 °C. Based on these results, a temperature range of 28 °C to 32 °C is proposed as the optimum temperature for the growth of S. frugiperda.

Do alternative resources dampen functional responses of native but not alien gammarids?

While aquatic invasive predators are among the most impactful trophic groups, we lack the understanding of whether alternative food resources mediate adverse predatory effects and stabilize native prey communities. Here, we use comparative functional responses to examine the influence of alternative food resources (Fucus sp.) on predator–prey interaction strengths from three gammarid crustaceans, with one native (Gammarus locusta) and two existing and emerging invasive (Gammarus tigrinus, Pontogammarus maeoticus, respectively) species, towards larval chironomid prey. All gammarids exhibited Type II functional responses, irrespective of the presence of alternative seaweed disks. Fucus sp. disks significantly reduced predation rates overall; however, significant reductions in maximum feeding rates (i.e., functional response magnitudes) were only evident in the native species and not for the two invaders. Our results thus may suggest that alternative resources dampen the predatory interaction strength of native but not invasive alien species, concerning these three study organisms. This potentially exacerbates the impacts of invasive predators relative to natives in diverse communities. Studies should increasingly consider alternative resources when quantifying ecological impacts of current and future invasive alien species compared with natives.

A z-gradient array coil with a dedicated active-shielded array coil for MRI.

An array-based z-gradient coil with a set of programmable power amplifiers can outperform a conventional z-gradient coil and make it highly customizable with a broader range of tunable features. A dynamically adjustable imaging volume can be achieved using a pair of independent arrays and a modified optimization procedure based on analytic equations. Two modes of operation are provided: (a) standard mode that resembles a conventional coil; (b) advanced mode, where all performance parameters can be adjusted employing a controllable feeding mechanism. Commercial software is used to demonstrate the validity and feasibility of the proposed coil. Primary and shield array diameters are 24 and 30 cm, both of which comprise 12 bundles of 10 turns copper wires. Maximum feeding voltage/current is 250 V/100 A for all array elements. Four distinct magnetic profiles are provided: (a) conventional profile with 140 mm diameter spherical region of interest, 120 mT/m gradient, and up to 4500 T/m/s slew rate; (b) profile of 200 mT/m, 70 mm region of interest, and up to 6900 T/m/s slew rate; (c) 60 mm axially shifted 70 mm region of interest with 120 mT/m strength and 3600 T/m/s slew rate; and (d) profile of 370 mT/m, 120 mm region of interest, and 3700 T/m/s slew rate when the active shield is reverse fed. By using an active-shielded gradient array coil, the magnetic field profile of the imaging volume can be adjusted dynamically, and it can provide new features and a wide range of field profiles for diverse applications in MRI.

Feeding of Fish at the Seamounts of the Whale Ridge (South-Eastern Atlantic Ocean). 2. Splendid alfonsino Beryx splendens (Berycidae)

The feeding characteristics of splendid alfonsino Beryx splendens from the seamounts of the Whale Ridge have been studied. A wide range of food organisms in feeding of splendid alfonsino has been confirmed, comprising meso- and macroplankton of the sound-scattering layers of the mesopelagial. Benthic organisms have not been found in the food spectra of splendid alfonsino. The food spectra of splendid alfonsino differ in populations inhabiting distant groups of the seamounts of the Whale Ridge due to the difference in the composition of the available food items and environmental conditions, fish body size, season, and sampling period. Splendid alfonsino has a pronounced diurnal feeding dynamics: the fish feed most intensively in the evening and at the beginning of the night, when the organisms of the sound-scattering layers migrate to the upper water layers. At this time, maximum feeding and minimum digestion of food are noted. Splendid alfonsino selects organisms of 0.9–130.0 mm (on average, 36.1 mm) in size for feeding. As the body length increases, splendid alfonsino switches to feeding on larger prey, while the ratio of the size of the prey to the size of splendid alfonsino changes little (9.7–11.5%).