Maximum Feeding Research Articles

Anthropogenic water conditions amplify predatory impact of the non-native Oriental river prawn Macrobrachium nipponense

Investigating non-native species’ impacts on recipient communities in the context of local habitat conditions is vital to understanding their potential invasiveness. This study used comparative functional response experiments to assess the potential predatory impacts of the non-native Oriental river prawn Macrobrachium nipponense compared to the native Malayan river prawn Macrobrachium malayanum in Singapore. Functional responses of these species were compared under different water temperature and pH conditions, representing Singapore’s warmer, near-neutral artificial/modified fresh waters, and cooler, more acidic natural forest streams, where the two species are respectively abundant. Four water condition treatments of different temperature-pH permutations were tested: A (26 °C, pH 5.5), B (26 °C, pH 6.5), C (29 °C, pH 5.5) and D (29 °C, pH 6.5). Results found both species to exhibit Type II functional response across all treatments, but M. nipponense responses were significantly higher than those of M. malayanum in all of them. Overall, its functional response was also significantly amplified when water conditions resembled that of the artificial habitat, with higher attack rate, lower handling time, and higher maximum feeding rate. Results imply that M. nipponense can inflict ecological impact in Singapore in terms of predation on the invertebrate prey community. The predatory impact of M. nipponense can also be exacerbated by changes in water parameters (i.e. increasing temperature and/or pH) associated with anthropogenic change, highlighting the importance for conservation of natural freshwater habitats in Singapore.

Process analysis of biconvex tube hydroforming based on loading path optimization by response surface method

Biconvex tube is prone to problems such as severe wall thickness reduction or wrinkling in hydroforming due to the big diameter-thickness ratio and large expansion ratio. In this paper, the segmented dies were employed to manufacture the biconvex tube, and the forming performance of the part under different loading paths was simulated by ABAQUS/Explicit software, then the corresponding results were obtained. The influence of loading path–related factors on the formability of the biconvex tube was analyzed by the response surface method. Based on the optimization evaluation criteria, the predicted loading path was determined to be linear loading, and the maximum axial feeding was 13 mm and the maximum internal pressure was 89 MPa.

Efficacy of Edible Oils and Dried Leaf Powders Against Callosobruchus Maculatus F. On Cowpea

Laboratory experiment was conducted to find out the efficacy of edible oils and dried leaf powders against the pulse beetle Callosobruchus maculatus (F.) on cowpea seeds. The results revealed that among the edible oils groundnut (Arachis hypogea) oil was the most effective with less seed damage (6.98%), weight loss (1.30%) and maximum feeding index (97.66%) followed by mustard (Brassicajuncea) and gingelly (Sesamum indicum) oil. Among the plant powders, neemAzadirachta indica resulted in less seed damage (19.65%), weight loss (26.64%), and high feeding index (50.63%) followed by Eucalyptus globulus and Ipomoea sp. Both edible oils and dried leaf powders do not affect the germination of cowpea seeds up to 60 days of treatment.

Effects of perceived competition and water temperature on the functional responses of invasive and native crabs

As the frequency of species introductions increases globally, the need for predicting the ecological impacts of invaders becomes ever more urgent. Functional responses, i.e. how resource uptake by consumers changes as a function of resource density, describe the species-specific ability to deplete resources under standardized conditions, and their shape has been used as a tool to predict the impact of non-native species. However, functional responses are usually derived from individuals foraging alone, which overlooks the important roles of intra- and interspecific interactions in shaping per capita consumption rates. We tested the extent to which the functional responses of invasive European green crabCarcinus maenasand native graceful rock crabMetacarcinus gracilisare affected by the perceived presence of con- and heterospecific individuals. Overall, crabs did not consume significantly more prey in the perceived presence of either a conspecific or novel heterospecific, but did demonstrate significantly higher attack rates in warmer water in the presence of a conspecific. Regardless of competitor type, green crabs consumed, on average, 16% more prey than the native crabs. This was largely due to their higher attack rate and lower prey handling time in warmer water. Green crab prey consumption increased significantly with increasing water temperature while that of the native crab species was unaffected (12 vs. 3.5% per 1°C increase, respectively). Higher maximum feeding rates are congruent with green crab impacts throughout their invaded range and suggest that green crabs might be undeterred from feeding in the presence of this co-occurring native crab species.

EFFECT OF REPLACEMENT OF CLOVER HAY BY DIFFERENT LEVELS OF PANICUM MAXIMUM ON REPRODUCTIVE PERFORMANCE OF V- LINE RABBIT DOES

Twenty V-line rabbit does aged 5 months, weighing about 2.925.6 ± 6.69kg were used in the present experiment to evaluated the effect of different levels of Panicum maximum 15, 30 and 45% replacement of clover hay on reproductive performance of rabbit does. Rabbit does were randomly distributed -into 4 groups. Group (1) fed control diet, group (2), group (3) and group (4) were fed 15%, 30 and 45% Panicum maximum respectively, replacement of clover hay. Results could be summarized as follows: 1- Change in weight of the does were significantly decreased with 15% and 30% Panicum maximum feeding diets during gestation period compared with control, while change in weight at pregnant insignificantly differed to control when replacing 45% Panicum maximum to clover hay. 2- Feed intake was significantly increased with replacing different levels of Panicum maximum at pregnant period and replacing 30 and 45% panicum at lactating does. 3- Litter weight .and litter weight gain of kids with rabbits fed diets containing 45% panicum maximum at week1 until week 4 were close to data of litter weight with rabbit fed control. Mortality rate was not significantly different between different treatments. 4- Inclusion of 45% Panicum maximum significantly recorded the highest milk yield during the four weeks of lactation compared with others groups, litter weight .and litter weight gain and the highest economical efficiency. Conclusively, it is possibility to replace 45 % of clover hay by Panicum maximum of the rabbit does diets

Identification of Freshwater Zooplankton Functional Groups Based on the Functional Traits of Species

Information on the functional traits of the most widespread species of freshwater zooplankton (Rotifera, Cladocera, and Copepoda) in European Russia was collected and analyzed. Our database includes 355 species described by 4 traits, namely: maximum body length, trophic group, feeding type, and movement type. Cluster analysis based on Gower's functional distances shows that freshwater zooplankton can be classified into 19 groups with different ecological roles. The characteristics of each identified functional group are presented. We believe it to be fundamentally important to build a unified classification using all available data and applicable characters for all three main taxonomic groups of zooplankton. Comparison with the existing ecological zooplankton classification proposed by Yu. S. Chuikov has demonstrated a number of advantages of our approach. Several ecological groups in Yu. S. Chuikov’s classification are represented by more fractional categories in our classification. Our system of functional groups can be used in studies of the structure of zooplanktocoenoses based on direct cluster analysis and ordination or based on functional distances between samples. To calculate the functional similarity between species, one can use our database of features, which is contained in the Appendix. Analysis based on functional groups gives a better unerstanding of the structure of a community than traditional ordination, which takes into account only the taxonomic affiliation of species. The approach used for functional group identification can be useful in assessing functional diversity and identifying patterns of freshwater zooplanktocoenoses dynamics. The database of functional signs of zooplankton can be used to check the relationship of functional signs with environmental factors.

Ecological impacts of an invasive predator are mediated by the reproductive cycle

Predicting the ecological impacts of invasive species is impeded by context-dependencies that can mediate the strength of trophic interactions. Reproductive status is a pervasive context across trophic and taxonomic groups, yet has mostly been neglected in studies of invader impact. The present study examines the influence of the reproductive cycle on predatory impacts of a known damaging invasive freshwater crustacean, Gammarus pulex (Amphipoda), using a comparative functional response approach. Across females that were non-ovigerous, or had immature- or mature-stage embryonic broods, all G. pulex exhibited potentially prey destabilising Type II functional responses towards chironomid larvae. Attack rates were highest by immature embryonic brood stages, and significantly lower by mature embryonic brood stages. Conversely, handling times were consistently lower, and hence maximum feeding rates higher, where broods were present as compared to absent. These predatory patterns may reflect changing resource demands for progeny development across the reproductive cycle, the influence of brood bulk, female moult stage and/or motivational aspects of feeding, such as avoidance of filial cannibalism. Accordingly, many aspects of reproduction may alter the intensity of predatory impacts by invasive species. Future studies considering invader impacts should consider the influence of sex and reproductive status to more holistically quantify and predict population-level invader impacts.

Comparative functional responses predict the predatory impact of the highly invasive fish Cichla kelberi

Peacock basses (genus Cichla) are a group of Amazonian predatory fishes that invaded many systems worldwide. Severe ecological impacts have been reported, but no study investigated the functional response of these fishes to variations in prey abundance, a crucial information to determine predator consumption and impact. In this study, we evaluated the functional response of the highly invasive Cichla kelberi toward prey species of different taxonomic groups, and compared it to the response of the wolf fish Hoplias malabaricus, a voracious predator used as baseline. We hypothesized that higher feeding rates drive the predatory impact of the invasive predator. Using a non-replacement experimental setup, we manipulated prey densities (fish and shrimp) in 1000-L mesocosm tanks to quantify the consumption response of each predator during 24 h. Both predators consumed more fish than shrimp, but C. kelberi consumed significantly more than H. malabaricus. We found that C. kelberi consistently displayed higher Type-II functional response than H. malabaricus toward both prey species. There was a non-significant effect of predator species on attack rates, but C. kelberi presented significantly lower handling time values and higher maximum feeding rates. Our findings provide empirical evidence that high individual consumption rates explain the predatory impact of the highly invasive C. kelberi, and predict strong effects on invaded communities.

Industrial Robotic Arm for Chil l i Milling Process

Chilli (Capsicum annuum), one of the essential ingredients in Sri Lankan cuisine, is widely cultivated for producing dried chilli. The narrow conical-shaped chilli pods with wrinkled surface do not support much of the existing common mechanical feeding systems such as augers or bucket conveyorsin the chilli processing plants. Therefore, the objective of this study is to design and develop a robotic arm with a proper grabbing technique to feed chilli into the grinding mill. Furthermore, it is intended to install the developed robotic arm in an industrial level processing plant to test the feasibility of theindustrial application.The industrial robot designed in this study is primarily composed of three parts: the base, the arm and the wrist. These components connect with joints to form a unit. At the end of the wrist, an end-effector, which is a gripper for grasping chilli pods, is located.ATmega328 microcontroller, micro switches and DC motors were used to operate the robotic arm. The feeding rate is automatically controlled using a Hall Effect sensor. The robotic arm grabber was placed on top of the chilli containing trough (2.5m wide, 10.5m long, and 1.25m high) of an industrial level chilli processing plant.When operating, the grabber could grab 1.640±0.128 kg of chilli from the bulk in a single operation. The average time taken for one complete cycle of grabbing chilli, lifting the grabber, turning the arm on to the conveyer and releasing chilli on to the belt conveyor, varies from 20 s and 30 s depending on the height of chilli in the trough. The feeding rate varies from 440.6 kg/h and 218.66 kg/h when chilli is grabbed from the top and the bottom layers respectively. Therefore, this system can be recommended for maximum feeding rate of chilli up to 218.66 kg/h. Capacity can be increased by adding the same mechanism parallel or scaling up the existing system.

Determination of in situ degradation parameters and feeding level of pineapple (Ananas comosus L.) cannery by-product to Hanwoo steers.

ObjectiveThe objectives of this study were to determine the in situ degradation parameters and appropriate feeding level of pineapple cannery by-products (PCB) based on the growth performance and blood parameters of growing Hanwoo (Bos taurus coreanae) steers fed various levels of PCB.MethodsTwo ruminally cannulated Holstein cows were used for in situ disappearance rate measurements. Nylon bags (5×10 cm, 45 μm pore size) filled with 5 g of PCB in triplicate were inserted into the ventral sac of the two cannulated Holsteins cows and incubated for 0, 2, 4, 8, 16, 24, and 48 h. A total of 16 castrated growing Hanwoo steers (12.5±0.5 months old, 302.9±25.7 kg of initial body weight [BW]) were used for the experiment. Animals were stratified by initial BW and then randomly assigned to one of four experimental diets (0%, 1.5%, 3.0%, or 6.0% of PCB, on the dry matter [DM] basis) fed for 91-d, including 30-d of adaptation.ResultsSoluble fraction a of DM and crude protein (CP) was 61.9% and 86.0%, fraction b of DM and CP was 32.7% and 11.2%, and indigestible fraction c of DM and CP was 5.4% and 2.8%. The 6.0% PCB feeding group showed lower productivity compared to animals in the other treatments. Increasing the dietary level of PCB did not alter DM intake, but it was numerically lowest in the 6.0% feeding group. The gain to feed ratio was linearly decreased by increasing of PCB. The quadratic broken-line test estimated that 2.5% (DM basis) was the maximum feeding level of PCB in growing Hanwoo steers (y = 0.103 − 0.001×[1.245−x]2, R2 = 0.18).ConclusionDiets containing up to 2.5% PCB can be fed to growing Hanwoo steers without adverse effects on growth performance.

Determination of fitness traits of Orius strigicollis Poppius (Hemiptera: Anthocoridae) on Pectinophora gossypiella (Lepidoptera: Gelechiidae) using two-sex life table analysis.

BackgroundPink bollworm (Pectinophora gossypiella) is a destructive insect pest of cotton crops in China and globally, which is actively predated on by Orius strigicollis. Studies on the fitness or survival of O. strigicollis fed on P. gossypiella at different temperatures have not been reported. The fitness of O. strigicollis may be well explained using two-sex life table parameters. Thus, the present study provides important insights for the effective biocontrol of P. gossypiella.MethodologyConsidering the importance of fitness parameters and biocontrol, the present study explores the feeding potential and age-stage, two-sex life table traits of O. strigicollis on P. gossypiella eggs at different temperatures (24, 28 and 32 °C) in the laboratory.ResultsThe intrinsic rate of increase (r) was higher at 28 °C (0.14 d−1) than at 24 °C (0.0052 d−1) and 32 °C (0.12 d−1). Similarly, the net reproductive rate (R0) was higher at 28 °C (17.63 offspring) than at 24 °C (1.13 offspring) and 32 °C (10.23 offspring). This concluded that the maximum feeding potential and growth capacity of O. strigicollis could be attained at 28 °C when fed on P. gossypiella eggs. O. strigicollis adults preferred to feed on P. gossypiella eggs compared with first instar larvae. Based on these results, the present study suggests that O. strigicollis represents a promising biological control agent against P. gossypiella eggs in cotton fields.

Intense deposition and rapid processing of seafloor phytodetritus in a glaciomarine fjord, Andvord Bay (Antarctica)

The West Antarctic Peninsula (WAP) region encompasses numerous fjords known to be hotspots of benthic biodiversity and biomass. These ecosystems are undergoing rapid climate warming and oceanographic change; consequent glacial melt and retreat may dramatically alter benthic communities and ecosystem functions in WAP fjords. In addition, there is extreme variability in seasonal productivity and phytodetrital food input to the deep shelf benthos of the WAP. Here we document the flux and utilization of phytodetritus at 530 m depth in Andvord Bay, a WAP glaciomarine fjord, using seafloor time-lapse images spanning a 10-month period, from December 2015 to September 2016. To explore the relationship between sea-surface conditions and detrital export, we developed a color-based method to quantify seafloor phytodetritus cover in time-lapse images, and correlated phytodetritus cover with sea-ice cover and surface wind speed. During the most rapid period of phytodetritus accumulation in early January 2016, approximately 3 cm of phytodetritus was deposited on the fjord floor over six days, representing a large input of organic carbon to the benthos. The timing of this rapid export event was not related to overlying wind conditions and occurred when the fjord was ice-free. To assess the response of the megafaunal community, we measured fecal-pellet production by the dominant surface deposit-feeder, the ampharetid polychaete Amythas membranifera. The deposit-feeding rate of A. membranifera increased substantially during high seafloor phytodetritus cover and returned to background levels for the rest of the autumn and winter. Ampharetids and mobile megafauna were observed to feed throughout the entire time-series, including beneath winter sea ice, suggesting that the delivery of phytodetritus from surface phytoplankton blooms in spring/summer sustains these abundant populations year-round with a sediment food bank. A. membranifera can reach densities of >37 m−2 and, as a population, processes a volume equivalent to the top 1.05 cm of sediment annually. The maximum individual feeding rates measured are comparable to some temperate intertidal deposit feeders. Nonetheless, phytodetritus on 31–73% of the seafloor was consumed by macrofauna or microbial populations not visible in time-lapse photographs, suggesting that recently deposited phytodetritus is processed primarily by these smaller size classes. This study demonstrates the seasonal coupling and subsequent decoupling of detritivore activity in response to a massive detrital deposition event in a deep, subpolar WAP fjord. This work indicates that both megafaunal deposit feeders and smaller size classes play important roles in processing labile organic matter in WAP fjord ecosystems.

Loading path design of thin-walled aluminum alloy T-shaped tube hydroforming process based on the control of limit pressure

Due to the influence of pressure control precision, the actual pressure in hydroforming process for the tube is usually greater than the design pressure, which causes the fracture of tube. The loading path of T-shaped tube hydroforming process was designed based on the control of limit pressure. First, the limit pressure of tube Pmax was obtained by improving the internal pressure until the tube cracked in the T-shaped tube hydroforming process without the feeding and a theoretical model for predicting instantaneous pressure is developed. Second, the tube bulge height Hmax and the maximum feeding Dmax were explored through manual operation of feeding and pressure in hydroforming machine, in which the overflow pressure is set to Pmax by using an overflow valve; finally, the loading path of internal pressure and feeding was designed using the ladder growth and linear growth in T-shaped tube hydroforming experiment in which the maximum pressure, the maximum feeding, and the overflow pressure (equal to internal pressure) were set to Pmax, Dmax, and Pmax, respectively. The results show that the obtained limit pressure Pmax can avoid the overpressure of the tube and restrain the fracture of the tube through the action of the overflow valve. Meanwhile, the accuracy of the prediction model to figure up Pmax was verified through experiments: the theoretical prediction value of the established model was consistent with the experimental true value. Compared with the T-shaped tube formed by linear loading path, the wall thickness of the formed T-shaped tube by ladder loading path is more evenly distributed without wrinkles and fractures and the height of the formed branch tube close to Hmax. At the same time, it is found that under the differential lubrication tube blank, the time of obtaining a suitable loading path is significantly reduced, and the collocation of ladder mode is simpler and more efficient.

Inter-Population Similarities and Differences in Predation Efficiency of a Mosquito Natural Enemy.

Predation is a critical factor that mediates population stability, community structure, and ecosystem function. Predatory natural enemies can contribute to the regulation of disease vector groups such as mosquitoes, particularly where they naturally co-occur across landscapes. However, we must understand inter-population variation in predatory efficiency if we are to enhance vector control. The present study thus employs a functional response (FR; resource use under different densities) approach to quantify and compare predatory interaction strengths among six populations of a predatory temporary pond specialist copepod, Lovenula raynerae, from the Eastern Cape of South Africa preying on second instar Culex pipiens complex mosquito larvae. All individuals from the sampled populations were predatory and drove significant mortality through per capita predation rates of 0.75-1.10 mosquitoes/h at maximum densities over a 5-h feeding time. Individuals from all copepod populations exhibited Type II FRs with no significant differences in attack rates. On the other hand, there were significant differences in handling times, and therefore also maximum feeding rates (maximum experimental prey density: 32), suggesting possible genetic differences among populations that influenced predation. Owing to a widespread distribution in arid landscapes, we propose that predatory calanoid copepods such as L. raynerae play a key regulatory role at the landscape scale in the control of disease vector mosquito populations. We propose that these ecosystems and their specialist biota should thus be conserved and enhanced (e.g., via selective breeding) owing to the ecosystem services they provide in the context of public health.

Lack of biotic resistance to an invasive bivalve irrespective of season or hydrodynamic disturbance

Coastal ecosystems are subject to a wide variety of abiotic variation including seasonal fluctuations and hydrodynamic disturbance, which can influence species distributions. Additionally, introductions of invasive species are creating biotic pressures within coastal ecosystems, which can influence biological interactions. With the recent development of combining comparative functional responses, prey switching and biotic resistance theory in invasion ecology, invasion success and ecological impacts of invaders can be better quantified. Further, the incorporation of environmental contexts with these approaches allows predictions of invader success under a range of ecological scenarios. We examined the functional responses and prey switching propensities of the native European green crab, Carcinus maenas (Linnaeus, 1758), towards native blue mussels, Mytilus edulis (Linnaeus, 1758), and invasive Pacific oysters, Crassostrea (Magallana) gigas (Thunberg, 1793), under the abiotic contexts of season (winter vs summer) and hydrodynamic disturbance level (high vs low). In general, when each prey species was offered separately, C. maenas maximum feeding rates were higher towards native M. edulis compared to invasive C. gigas. In addition, handling times were lower, and thus maximum feeding rates were higher, in summer compared to winter. Hydrodynamic disturbance level had no significant influence on handling times or maximum feeding rates towards either prey species. When prey species were offered simultaneously, C. maenas disproportionately consumed native M. edulis over invasive C. gigas irrespective of proportional availability. In addition, increased hydrodynamic disturbance further increased the disproportionate consumption of M. edulis over C. gigas. We thus demonstrate that C. maenas offers little biotic resistance to invasions of C. gigas under a range of abiotic contexts, and indeed some of these contexts may exacerbate the invasion. We suggest that combined functional response and prey switching studies provide a wealth of information regarding invasion success and biotic resistance towards invasive species under environmental variation.

Context-dependent differences in the functional responses of conspecific native and non-native crayfishes

Invasive species are proliferating globally and cause a range of impacts, necessitating risk assessment and prioritization prior to management action. Experimentally derived estimates of per capita effects (e.g. functional responses) have been advocated as predictors of field impacts of potential invaders. However, risk assessments based on estimates from single populations can be misleading if per capita effects vary greatly across space and time. Here, we present a large-scale, multi-population comparison of per capita effects of the American spinycheek crayfish, Faxonius (formerly Orconectes) limosus—a species with an extensive invasion history in eastern North America and Europe. Functional responses were measured on individuals from six geographically disparate populations of F. limosus in its native and invaded ranges on two continents. These revealed inter-population differences in both the maximum feeding rate and functional response type that could not be explained by the biogeographic origin of the population nor by time since the invasion. We propose that other differences in source communities (including the presence of competitors) impose selective pressures for phenotypic traits that result in dissimilar per capita effects. We also compared functional responses of the congeners F. limosus and F. virilis in the presence and absence of potential competitors to examine indirect competitive effects on feeding behaviour. The maximum feeding rate of F. limosus, but not F. virilis, was suppressed in the presence of heterospecific and conspecific competitors, demonstrating how the per capita effects of these species can differ across biotic contexts. In the competitor-presence experiments, individuals from the invasive population of F. limosus consistently had a higher maximum feeding rate than those of the native F. virilis, regardless of treatment. Our results caution against invasion risk assessments that use information from only one (or a few) populations or that do not consider the biotic context of target habitats. We conclude that comparative functional responses offer a rapid assessment tool for invader ecological impacts under context dependencies when multiple populations are analyzed.

Optimization of Cold Pressing Process Parameters of Chopped Corn Straws for Fuel

Pressed condensation is a key process before the reclamation of loose corn straws. In this study, the effects of stabilization time on the relaxation density and dimensional stability of corn straws were studied firstly, and then the stabilization time was determined to be 60 s by comprehensively considering the compression effect, energy consumption, efficiency and significance. On this basis, the effects of the water content (12%, 15%, 18%), ratio of pressure maintenance time to stabilization time (0, 0.5, 1), maximum compression stress (60.4, 120.8, 181.2 kPa) and feeding mass (2.5, 3, 3.5 kg) on the relaxation density, dimensional stability coefficient, and specific energy consumption of post-compression straw blocks were investigated by the Box–Behnken design. It was found that the water content, ratio of pressure maintenance time to stabilization time, maximum compression stress, and feeding mass all very significantly affected the relaxation density, dimensional stability coefficient and specific energy consumption. The interaction between water content and maximum compression stress significantly affected both relaxation density and specific energy consumption. The interaction between the ratio of pressure maintenance time to stabilization time and feeding mass significantly affected the dimensional stability coefficient. The factors and the indices were regressed by quadratic equations, with the coefficients of determination larger than 0.97 in all equations. The optimized process parameters were water content of 13.63%, pressure maintenance time of 22.8 s, strain maintenance time of 37.2 s, maximum compression stress of 109.58 kPa, and raw material feeding mass of 3.5 kg. Under these conditions, the relaxation density of cold-pressed straw blocks was 145.63 kg/m3, the dimensional stability coefficient was 86.89%, and specific energy consumption was 245.78 J/kg. The errors between test results and predicted results were less than 2%. The low calorific value of cold-pressed chopped corn straw blocks was 12.8 MJ/kg. Through the situational analysis method based on the internal and external competition environments and competition conditions (SWOT analysis method), the cold-pressed chopped corn straw blocks consumed the lowest forming energy consumption than other forming methods and, thus, are feasible for heating by farmers. Our findings may provide a reference for corn straw bundling, cold-press forming processes and straw bale re-compressing.

Efficacy of biopesticides against major arthropod pests and their natural enemies on okra

Efficacy of six biopesticides against insect pest of okra was evaluated in terms of population reduction over control during kharif, 2016 and 2017. Four foliar applications were done and results revealed that all the treatments were effective. Neem-baan was the most effective at 3rd and 7th day in all the sprays against whitefly (65.25, 28.80), (64.35, 27.88), (64.82, 27.71), (63.65, 26.54) and leafhopper, (64.08, 26.35), (64.09, 27.20), (64.45, 27.44), (64.39, 27.35), respectively. Neem baan was also effective at 3rd and 7th day against red spider mite during 4th spray and brought significant reduction in the shoot and fruit borer infestation up to 62.67%. Biopesticides treatments did not show any detrimental effect on the coccinellids and spiders’ populations. However, in laboratory experiments neem based pesticides brought significant reduction when treated aphid (A. gossypii) was fed to both species of coccinellids viz., C. septempunctata and C. sexmaculata. 3% neem oil reported maximum feeding reduction (28.05%) for C. septempunctata while in C. sexmaculata it was 34.74%.

Feeding inhibition with bioformulations in cut worms Agrotis ipsilon (Hufnagel)

Feeding inhibition study of bioformulations viz., Neemastra, Agniastra, Brahmastra, Dashparni ark and garlic + ginger + mint mixture was carried out against fourth, fifth and sixth instar larvae of A. ipsilon. These bioformulations were observed to be not giving significant mortality in the fourth, fifth and sixth instar larvae but result in feeding inhibition. Concentrations ranging from 1.5% to 24% were evaluated for this action. It was observed that Dashparni ark was the most effective causing maximum feeding inhibition to later instar larvae of A. ipsilon followed by Brahmastra, Agniastra, Neemastra and garlic+ ginger+ mint mixture. Dashparni ark was found 1.35, 1.34 and 1.26x more effective compared to the least effective garlic + ginger + mint mixture against fourth, fifth and sixth instar larvae of A. ipsilon, respectively.

Experimental and analytical study of the polymer melt flow through the hot-end in material extrusion additive manufacturing

Material extrusion additive manufacturing utilizes a thermoplastic polymer in the form of a solid filament as a built material. The polymer melts inside the hot-end channel and flows under the pressure generated by the filament feeding force. The flow of polymer through the hot-end is not fully understood yet, as it involves many complex phenomena, such as phase transition, shear rate and temperature dependent viscosity, as well as viscoelastic effects. In this paper, we investigate experimentally the filament feeding force, as a function of the feeding rate, for different materials (PLA and ABS), liquefier temperatures, nozzle diameters, and lengths of the liquefier. Two extrusion regimes are identified: a linear regime with a stable flow, and a non-linear regime with fluctuations in the feeding force, which are concomitant to unstable extrusion. Increasing the liquefier length and liquefier temperature are found to extend the linear extrusion regime. It is shown that the filament feeding force predicted by the analytical models available in the literature deviates from the measurements, especially at high feeding rates. A model solely based on heat transfer considerations is proposed to estimate the maximum feeding rate before the extrusion becomes unstable. The modelling results agree well with the measurements. The model can be used to select the hot-end design as well as appropriate printing parameters.