Food Conversion Efficiency Research Articles

Development of agrivoltaic insect net house to enhance sustainable energy-food production: a techno-economic assessment

Agrivoltaics (AV) systems are the simultaneous land utilization for sustainable energy and food production. However, AV may not be suitable for some crops that require rigorous pest management. This study has applied an innovative approach, combining AV with an insect net house to cultivate capsicum. The 1.8 kW AV system has been installed at a 3-m elevation to facilitate unrestricted tractor manoeuvrability for various farming operations. The structure can withstand winds as high as 140.4 km/h. The system has a 3,612-kWh energy capacity and a 51.41 kg food production capacity. The system's energy and food conversion efficiency are 14.09% and 154.8%, respectively, compared to the traditional systems. Economic metrics like a 2.20 benefit-cost ratio and a 9.39-year payback period have been included in the findings. Further, the land equivalence ratio is 1.97, indicating a better system than traditional AV and agriculture approaches.

Role of food conversion efficiency due to predation of prey populations in an eco-epidemiological model with allee and refugia

Role of food conversion efficiency due to predation of prey populations in an eco-epidemiological model with allee and refugia

TOXICITY OF SOME INSECTICIDES AND THEIR SUBLETHAL EFFECTS ON NUTRITIONAL INDICES OF FALL ARMYWORM IN SWEET CORN PLANT

Corn is a vital cereal crop in Bangladesh, significantly contributing to food security and economy. However, the fall armyworm Spodoptera frugiperda, poses a severe threat to corn cultivation. This study evaluates the toxicity of four insecticides and their effect on the nutritional indices of fall armyworm. Experiment was conducted from November 2022 to April 2023 with sweet corn variety BU Misty Vutta 1 at Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh. In this research four insecticides: Winmax 40 WDG, Ripcord 10 EC, Marshal 20 EC, and Shobicron 425 EC, were tested on fall armyworm larvae at multiple concentrations. The mortality of fall armyworm larvae was observed at 24, 48, 72, and 96 hours after treatment. Results indicated significant differences in larval mortality across treatments, with Shobicron 425 EC showing the highest mortality rate (100% at 72 hours after treatment), while Winmax 40 WDG showed the lowest. The median lethal concentration (LC50) and lethal concentration for 95% mortality (LC95) values supported the findings, with Shobicron 425 EC demonstrating superior efficacy. Additionally, Shobicron 425 EC resulted in the lowest food consumption (0.1), consumption index (0.2), Approximate digestibility (19.5%), Efficiency of conversion of ingested food (3.9%) and Efficiency of conversion of digested food (1.1%). The study concludes that Shobicron 425 EC is the most effective insecticide for controlling fall armyworm in sweet corn, suggesting its potential for integrated pest management strategies.

Bio-treatment of Cheese Whey by Black Soldier Fly Larvae (Hermetia illucens) reared in Algeria

Whey, a by-product of cheese industry, poses environmental challenges when discharged untreated. This study aimed to mitigate whey pollution and transform it into value-added products using black soldier fly larvae (BSFL). By investigating whey effects on BSFL growth and performance, an innovative waste management strategy was explored. The five-old-day larvae were fed with four diets; dry spent coffee ground (SCG) as the control diet, while SCG wetted with acid, sweet and fermented whey were the test diets. The results showed that whey types increased significantly (p < 0.05) BSFL growth compared to the control, the dry weight (53.83±0.49 Vs 25.10±0.18 mg/larva), growth rate (1.59±0.06 Vs 0.44±0.01 mg/day) and survival rate (78.83±1.25 Vs 68.50±1.5 %) of larvae and reduced their development time (28.00±01 Vs 37.00±01 day). Furthermore, mixing SCG diet with whey enhanced positively their performance by increasing the waste reduction (26.73±0.81 Vs 16.87±0.37 %), waste reduction index (0.85±0.03 Vs 0.45±0.01 %/day), approximate digestibility (36.49±1.52 Vs 20.29±0.53 %) and bioconversion rate (17.94±0.47 Vs11.65±0.52%). Adding whey to SCG diet increased protein content of BSFL (40.11% vs. 34.18%) and reduced fat (36.06 vs. 37.87 %) in dry mass. Whey also improved the composition of frass by increasing the phosphorus and total nitrogen levels. This approach demonstrates a sustainable solution for dairy industries waste, contributing to the circular economy and offering potential applications in animal feed and fertilizer production.

Zootechnical performance, feed efficiency and larval composition of Zophobas morio (Coleoptera: Tenebrionidae) fed with poultry litter-based diets

Abstract The yellow mealworm, super worm, and house cricket are among the most widely produced insects, with high feed conversion efficiency. However, their nutritional composition and development rate generally vary with environmental conditions. From an economic point of view, rearing conditions such as diet, temperature, and development time; insect performance such as mortality and nutritional value are the most important factors. In order to assess the development, growth, feed conversion efficiency, and chemical composition of Zophobas morio (Coleoptera: Tenebrionidae) larvae fed with diets containing poultry litter, an experiment was conducted. Five diets with varying levels of poultry litter inclusion (0, 25, 50, 75, and 100%) were used to replace the control diet (broiler feed), with five replicates containing 25 larvae per sample unit. Larval growth and development were assessed, and the chemical compositions of both the diet and Z. morio larvae were determined. Significant differences were observed among treatments for development time, survival rate, pupa weight, adult weight of Z. morio subjected to different poultry litter-based diets, as well as in the nutritional index bioassay. The longest development time and the highest larval mortality were observed in the 100% poultry litter-based diets. The highest percentage of crude protein in larval meal (%CP) was obtained with the addition of 25 and 50% poultry litter and was lowest with 100%. The incorporation of poultry litter into the diet of Z. morio has a multifaceted impact on growth and feed conversion efficiency. Elevated levels of poultry litter inclusion led to an extension in development time, yet food conversion efficiency attains optimization with an inclusion rate of up to 50%. Consequently, the decision regarding the proportion of poultry litter in the diet should be carefully weighed, taking into account breeding objectives, efficiency considerations, and cost factors. This ensures the attainment of an optimal balance between larval growth and nutritional efficiency.

Growth, nutrient uptake, blood metabolites and bone properties in broilers consuming feed with mineral-enriched whole black soldier fly larvae

Abstract The recycling of minerals is crucial for the future circular agriculture. Black soldier fly larvae (BSFL) can accumulate minerals in their body. This study investigated the effects of adding mineral-enriched BSFL, grown on substrates containing sewage sludge recyclates (SSR), to broiler feed to reintroduce minerals from waste streams currently subject to regulatory restrictions back into the nutrient cycle. Feed, nutrient, mineral and heavy metal intake, growth, blood metabolites and immunoglobulins, bone characteristics and mineral status of broilers were studied in response to different mineral-enriched BSFL supplements. Eighty newly-hatched mixed-sex Ross 308 chicks were divided into four groups, with six replicate pens per group. BSFL used in the broiler experiment were grown either on a modified Gainesville fly diet (FD) (L-FD) or on FD supplemented with 4% of sewage sludge biochar (L-BCH), or on the FD supplemented with Single Superphosphate (SSP) SSR (L-SSP). All broilers were fed age-specific diets and either had no access to BSFL (CON) or received 15% of CON birds’ feed intake as defrosted BSFL from three different sources. Inclusion of 15% of mineral-enriched whole BSFL in broiler rations had no adverse effects on growth performance parameters, nutrient intakes, nutrient conversion efficiency, plasma metabolites and immunoglobulins (). Birds in BSFL supply groups had higher serum Ca concentrations than CON birds (). L-BCH supplied birds had a lower serum P than CON birds (). Tibial characteristics and mineral status of birds were not affected by larvae supply (). Heavy metal intake (manganese, iron, zinc, copper, arsenic, cadmium, lead, and mercury) of the birds was not affected by dietary treatments (). In conclusion, 15% of mineral-enriched-BSFL reared on SSP can be included in broiler diets for 42 experimental days without adverse effects on nutrient intakes, growth performance parameters and bone condition.

Economical factitious diet for mass rearing of greater wax moth, Galleria mellonella (Lepidoptera: pyralidae), a promising host for entomopathogenic nematodes

BackgroundGreater wax moth (Galleria mellonella L.) (Lepidoptera: Pyralidae) is most commonly used for mass multiplication of entomopathogenic nematodes. An investigation on economical modification and comparative analysis of factitious diets of G. mellonella was carried out under laboratory conditions. Different diets were assessed in comparison with standard diet.ResultsModifications based on quantity change of dietary components (wheat flour, maize flour, dry milk, dry yeast, honey and glycerin), addition of vitamin E and vitamin-B complexes, elimination of dry milk and replacement of glycerin with sorbitol showed reduction in the cost of production and increase in food conversion efficiency in G. mellonella. The weight of larva in diet III (303.40 mg) was highest as compared to the larval weight in control diet (280.00mg). The conversion of ingested and digested food into biomass of G. mellonella was the highest for factitious diet III. Also, the highest number of Steinernema abbasi was produced from G. mellonella larvae reared on diet III (25418.43IJs) followed by diet I (21805.31IJs). The economics of the diets also showed that the percent cost reduction in factitious diet III and diet I was 48.86 and 28.85%, respectively. Overall, the results suggested that factitious diet III was superior to diet I followed by diet II.ConclusionAddition of supplements of vitamin E and B-complexes enhances the biological activity of the insect, thereby increasing its food conversion efficiencies. Factitious diet III can be successfully used for mass multiplication of the G. mellonella.

Assessment of the insecticidal efficacy of ethanol extract of Millettia pachyloba Drake leaves against Plutella xylostella Linnaeus moth

Plutella xylostella (L.), a menacing threat to cruciferous crops, exhibits cross-resistance to various chemical agents. The exploration of plant-derived insecticides emerges as an intervention strategy for the successful management of P. xylostella. Millettia pachyloba Drake is renowned as a traditional remedy for diverse health issues and has insecticidal properties. Experimental investigations in both laboratory and greenhouse settings utilized M. pachyloba extract (EMPE) at concentrations ranging from 2 to 10% (w/v). The objectives included inducing toxicity and controlling P. xylostella larvae effectively, assessing nutritional impacts through parameters like relative consumption rate (RCR), relative growth rate of larvae (RGR), efficiency of conversion of digested food (ECD), efficiency of conversion of ingested food (ECI), approximate digestibility (AD), and assimilation ratio (AR), and evaluating leaf damage inflicted by P. xylostella larvae on Brassica juncea. In the laboratory, the application of EMPE on P. xylostella larvae and pupae for 24, 48, and 72 hours yielded markedly higher mortality rates than the water-treated control (p < 0.05). Significant reductions in RGR, RCR, ECD, ECI, AD, and AR were evident throughout the larval stage (p < 0.05). In the greenhouse, EMPE treatments demonstrated notable differences from the water control treatment. On the 15th day of treatment, the EMPE treatment at 10% (w/v) exhibited the highest mortality rate (p < 0.05). Significantly reduced leaf damage was observed with EMPE treatments, displaying an inverse correlation with escalating concentrations. Particularly, the highest enhancement across all surveyed parameters was observed in the EMPE 10% (w/v) treatment, which was comparable to the positive control with fipronil (p > 0.05). Noteworthy differences in damage reduction percentage (DRP) were identified between EMPE contact treatments and the water control group (p < 0.05), indicating the promising potential of Millettia pachyloba extract for pest control.

Ageing and mating status affect food utilization efficiencies and assimilation of macronutrients in adults of Parthenium beetle, Zygogramma bicolorata Pallister

AbstractInvestigations of age‐based food conversion and utilization efficiencies in phytophagous insects are very few. Studies examining the effects of age, sex and mating status on biochemical assimilation of macronutrients by phytophagous insects are scarce as well. Hence, we designed the present study to evaluate the combined effect of age, sex and mating status on food consumption and utilization efficiencies, and the assimilation of macronutrients by the Parthenium beetle, Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae), on the invasive weed, Parthenium hysterophorus Linnaeus (Asterales: Asteraceae). We hypothesized that mated adults would consume and utilize more food than unmated adults, that assimilation of nutrients by old adults would be lower than young adults and that females would consume and utilize food more efficiently than males. However, our results revealed that as adults aged, their food consumption and utilization efficiencies decreased, and they assimilated less proteins and glucose in their body. Despite that, their mean body biomass and assimilation of triglycerides increased. While mated adults had higher food utilization efficiencies and increased assimilation of triglycerides and glucose, unmated adults assimilated more proteins. Females had higher food consumption rates and increased assimilation of nutrients, whereas males had higher food conversion efficiencies and growth rates. Furthermore, middle‐aged adults had higher food utilization efficiencies and they assimilated more nutrients than young and old adults. Our results therefore suggest compensatory feeding in adults of Z. bicolorata with ageing. We also recommend the release of more numbers of mated middle‐aged females to control P. hysterophorus in agro‐ecosystems.

Studies on Nutrition, Utilization and Hosts Preference of Feeding Fall Armyworm Larvae, Spodoptera frugiperda on Some Vegetable Crops Leaves

Ouda, M.I. 2024. Studies on Nutrition, Utilization and Hosts Preference of Feeding Fall Armyworm Larvae, Spodoptera frugiperda on Some Vegetable Crops Leaves. Arab Journal of Plant Protection, 42(3): 269-274. https://doi.org/10.22268/AJPP-001259 The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae), appeared in 2016 on maize crop in the Americas. Thereafter, it was recorded as an invasive pest in Africa during 2017. In Egypt, this study was conducted during 2022 to investigate the nutritional indices and host preference of the 3rd and 5th instars of FAW larval stage on fifteen vegetable crops under laboratory conditions. Experiments were conducted under constant temperature in an incubator at 27±1°C, relative humidity of 65±5% and a photoperiod of 14:10 hrs (light: dark). The results obtained showed that the hosts Beta vulgaris L., Cichorium intybus L., Fragaria x ananassa L., Brassica rapa L. and Zea mays L. var. everta were significantly favoured as primary hosts for FAW development. These hosts had higher larval and pupal weight and feeding indices: consumption index (CI), approximate digestibility (AD), efficiency of conversion of ingested food into body matter (ECI), efficiency of conversion of digested food into body matter (ECD) and relative growth rate (RGR). Whereas the hosts Vigna unguiculata, Lactuca sativa, Brassica oleracea var. capitata, Brassica oleracear var. botrytis, Eruca vesicaria subsp. sativa, Pisum sativum and Vicia faba were favored as secondary hosts for FAW development, with lower values for larvae and pupae weight and feeding indices. However, the larvae did not prefer and did not complete feeding on the hosts Cucumis sativus, Solanum lycopersicum and Phaseolus vulgaris. Keywords: Spodoptera frugiperda, biology, nutritional indices, host preference.

Selection of popcorn genotypes resistant to Spodoptera frugiperda and identification of resistance-related key traits


 The Spodoptera frugiperda, is one of the most deleterious pests of popcorn and the identification of resistant genotypes is determinant in breeding programs. The objective of this study was to select popcorn genotypes resistant to S. frugiperda and the key traits related to the identification of resistance. The popcorn varieties UEM J1, Composto Márcia, Arachida, Composto Gaúcho, and Zapalote Chico (resistant check) were evaluated in a completely randomized design with 100 replications. The experimental unit consisted of one Petri dish, containing plant material and a caterpillar The following traits were evaluated: larval stage duration (LSt), food intake weight(IW), final larva weight (FW), mean larva weight (MW), feces (F), assimilated (A) and metabolized food weight (M), relative consumption rate (RCR), relative metabolic rate (RMR), relative growth rate (RGR), conversion efficiency of ingested food (CEI), apparent digestibility (AD), conversion efficiency of digested food (CED), and leaf area consumed (LAC). The diagnosis of multicollinearity, analysis of canonical variables, genetic divergence, hierarchical clustering, factor analysis and canonical correspondence analysis were carried out to perform multivariate analysis. After the multicollinearity test, the traits FW, IW, RCR, AD, and LAC were maintained for further analysis. The traits IW, FW and AD were determinant in the resistance by antixenosis expressed by the varieties Zapalote Chico and Arachida, for the varieties Composto Gaúcho and Composto Márcia the determining characteristics were RCR and LAC and for the variety UEM J1 the variable LAC showed greater importance. Variety Arachida was considered resistant to S. frugiperda by antixenosis and can be used in the future as a source of favorable alleles to breed resistant popcorn hybrids. The traits relative consumption rate, apparent digestibility and leaf area consumed were considered key traits in the identification of resistance against S. frugiperda in popcorn genotypes.

Chicken caecal enterotypes in indigenous Kadaknath and commercial Cobb chicken lines are associated with Campylobacter abundance and influenced by farming practices

Identifying farming practices that decrease susceptibility to infectious diseases and optimise food conversion efficiency is valuable for chicken welfare and productivity, the environment, and public health. Enterotypes can be used to define microbial community phenotypes that have differential, potentially significant impacts on gut health. In this study, we delineated enterotypes by analysing the microbiomes of 300 indigenous Kadaknath and 300 commercial Cobb400 broiler chickens raised across 60 farms in western India. Using a compositional data approach, we identified three distinct enterotypes: PA1 (n=290), PA2 (n=142) and PA3 (n=67). PA1 and PA2 clustered more closely with each other than with PA3, however, PA2 had significantly lower alpha diversity than PA1. PA1 had a high Firmicutes: Bacteroides ratio, was dominated by Faecalibacterium and had a higher abundance of Prevotellamassilia than other enterotypes. PA2 was characterised by its low alpha diversity, a high abundance of the common taxa Phascolarctobacterium A and Phocaeicola dorei and a significantly higher Campylobacter abundance than PA1. PA3 had the highest Bacteroidota abundance of the three enterotypes and was defined by high prevalence of lower abundance taxa such as CAG-831 and Mucispirillum schaedleri. Network analysis showed that all enterotypes have different proportions of competing Firmicutes-dominant and Bacteroidota-dominant guilds. Random Forest Modelling using defined farm characteristics was predictive for enterotype. Factors affecting enterotype include whether farms were open, enclosed or caged, the location of farms, whether visitors were allowed inside, the number of people in contact with the chickens, chicken line, the presence of dogs and whether flock thinning took place. This study suggests that enterotypes are influenced by farming practices, hence modification of practices could potentially be used to reduce the burden of zoonotic pathogens such as Campylobacter.

Sublethal Effects of Lambda-Cyhalothrin, Imidacloprid, and Indoxacarb on Some of the Behavioral and Physiological Patterns of German Cockroach (Dictyoptera: Blattellidae)

German cockroach, Blattella germanica (L.), is a common household pets and a serious global public health risk. This study aimed to investigate the sublethal effects of lambda-cyhalothrin, imidacloprid, and indoxacarb on aggregation behavior, sexual communication, feeding efficiency, bodyweight, and nutritional indices of B. germanica. However, the study showed that the LD10 and LD25 doses of these insecticides impaired aggregation behavior and sexual communication of B. germanica; In addition, the data analyses of Excess Proportion Index (EPI), indicated that the aggregation response and sexual communication of adult cockroaches were decreased due to its exposure to LD10 and LD25 compared to the control treatment (LD0). Although the cockroaches’ food intake increased, their bodyweight decreased after being exposed to LD10 and LD25 compared with the control treatment. Moreover, a negative impact of LD10 and LD25 was observed on some nutritional indices e.g. approximate digestibility (AD), relative growth rate (RGR), and efficiency of conversion of digested food (ECD). On the other hand, the LD10 and LD25 have positively affected on other nutritional indices, including efficient conversion of ingested food (ECI) and relative consumption rate (RCR) when compared with control group. This study showed that the sublethal effects of lambda-cyhalothrin, imidacloprid, and indoxacarb employed to control insect pests widely, have considerable effects on the insect’s behavioral and physiological patterns.

Dynamics of Nutritional Indices in Fifth Instar Silkworm Bombyx Mori L. Parasitized with Beauveria Bassiana

Silkworm Bombyx mori is a small economically significant insect. Due to domestication for centuries, silkworms have become very gentle and subtle to the environmental conditions and micro-pathological agents which affect its metabolism, the food intake, dietary utilization, dietary efficiency, morpho-nutritional parameters such as olfactory organs and gene expression in the silkworm. Hence, the present research was focused to comprehend the dynamic changes in the nutritional parameters amalgamating the effects of infection of Beauveria bassiana in 5th instar silkworm compared to untreated silkworms. For the current investigation, the popular silkworm race bivoltine double hybrid (CSR2 X CSR27) X (CSR6 X CSR 26) was chosen. Various nutritional parameters such as ingestion of mulberry leaf, digestion, excretion, approximate digestibility, consumption index and reference ratio were estimated based on the dry weight of mulberry. The results indicated that food consumption, digestion of food ingested and excreta decreased in Beauveria bassiana parasitized silkworms. No significant variation was noticed in approximate digestibility and reference ratio from the first day to the fifth day of the instar, but on the sixth day, a significant drop in these two parameters was noticed compared to unparasitized worms. The consumption index was recorded higher in the experimental batch.

Post-spawning growth acceleration in fish as a result of reduced live weight and thus, increased food conversion efficiency

Post-spawning growth acceleration in fish as a result of reduced live weight and thus, increased food conversion efficiency

Effect of adding Cynara scolymus L. (artichoke) extract to water or diet on the productive performance of broilers

The experiment was carried out in the poultry field of the Department of Animal Production/College of Agriculture/the University of Diyala from 4/9/2021 to 10/14/2021 to study the effect of adding Cynara scolymus L. )artichoke( extract to the diet of broilers. It was used as an antioxidant to show its effect on birds' productive, physiological and immune performance. In this experiment, 225 unsexed Ross 308 hybrid broiler chicks were used (one day age), with an initial weight of 44.36 g/chick. These chicks were randomly distributed from the first day of receiving them to five experimental treatments with three replicates for each treatment (15 birds/repeat). The experimental treatments were: T1 = (control treatment) provided a standard diet free of additives, T2 = Standard ration plus 75 mg/L artichoke extract, T3 = a standard diet supplemented with 150 mg/L artichoke extract, T4 = Standard ration to which 2 g/kg of artichoke extract is added, and T5 = Standard ration to which 3 g/kg of artichoke extract is added. The experiment results indicated a significant effect on product traits when adding different artichoke leaf extract powder levels to Ross 308 broiler water and diet (1-42 days). Generally, treatment T3 was significantly (P<0.05) superior in the fourth week in recording the highest average live body weight of 3170.90 g, and treatment T4 was significantly (P<0.05) in the fourth week and recorded the highest rate of weight gain. Also, treatment T1 in the first week recorded the highest rate of feed consumption, treatment T2 in the first week recorded the highest efficiency of food conversion, and treatment T3 significantly (P<0.05) and recorded the highest rate of productive evidence. Keywords: broiler, artichoke leaf extract, productive traits

Impact of Plant Symbiotic Endophytic Fungus, Aspergillus terreus on Insect Herbivore Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae).

Herbivorous insects are known to be resistant to fungal endophytes that asymptomatically inhabit plant tissues. The insecticidal ability of the endophytic fungus Aspergillus terreus isolated from Catharanthus roseus against Spodoptera litura (Fabricius) was assessed in the current study. The survival and growth of S. litura were adversely impacted by the ethyl acetate extract of endophytic A. terreus. Fungal extract supplemented diet caused 14 to 94% larval mortality in comparison to 2% in control. Additionally, retarded insect growth was observed after ingestion of supplemented diet. The fungal metabolites were also observed to have an inhibitory influence on the adult emergence and reproductive potential of adults. Phytochemical analysis revealed the presence of phenolic compounds in the crude extract of endophytic fungus which may be responsible for toxicity. It was also determined how endophyte-infected cauliflower plants affected S. litura's survival and growth. Endophyte-infected plants exhibited resistance to S. litura by causing 54% larval mortality and delaying development by 5.2days. In comparison to uninfected plants, adult emergence, lifespan, fecundity and egg hatchability of insects was significantly decreased on infected plants. There was a significant decrease in relative growth and consumption rates as well as in the efficiency of food conversion, which indicates toxic and antifeedant effect of the fungus on S. litura. This suggests that endophyte-inoculated plants exhibit antibiosis against S. litura. In conclusion, the endophytic fungi having insecticidal activity could be used to develop alternative ecologically safe control strategies.

Insecticidal, genotoxic and biochemical effects of Shewanella sp. (SS4) and Thauera sp. (M9) on Spodoptera litura

AbstractSpodoptera litura (Fabricius) (Lepidoptera: Noctuidae) is a polyphagous pest causing economic losses to a number of agricultural crops. The present study was conducted to explore the insecticidal potential of some soil bacteria against S. litura. Among the tested bacterial isolates, Shewanella sp. (SS4) and Thauera sp. (M9) caused higher larval mortality. Concentration–response bioassays indicated a dose‐dependent increase in larval mortality with maximum mortality of 80 and 76%, respectively, due to Shewanella sp. and Thauera sp. Both the bacteria negatively affected the growth and development, reduced adult emergence and induced morphological deformities in adults. Nutritional parameters of S. litura i.e. relative growth and consumption rate, efficiency of conversion of ingested and digested food as well as approximate digestibility of food decreased with increasing bacterial concentrations. Histopathological studies revealed the disruption of peritrophic membrane and midgut epithelium of larvae. Profiles of digestive enzymes i.e. α‐amylases, α, β‐glucosidases and galactosidases, lipases and proteases were also significantly decreased with bacterial treatment. Comet assay test indicated DNA damage in larval haemocytes due to bacterial infection. These results imply that both these bacterial isolates have the potential as biological control agents and may prove as environmentally friendly alternative for pest management techniques.

Activation of the growth–IGF-1 axis, but not appetite, is related to high growth performance in juveniles of the Malabar grouper, Epinephelus malabaricus, under isosmotic condition

Salinity, a determining factor in aquatic environments, influences fish growth. Here, we evaluated the effect of salinity on osmoregulation and growth performance in juveniles of the Malabar grouper, Epinephelus malabaricus, a species of high commercial value in Asian markets; we also identified the salinity that maximized this species' growth rate. Fish were reared at 26 °C and under a 14:10 h photoperiod with a salinity of 5 psu, 11 psu, 22 psu, or 34 psu for 8 weeks. Change in salinity had minimal impact on the plasma Na+ and glucose concentrations, although the Na+/K+-ATPase (nkaα and nkaβ) transcript levels in the gills were significantly lower among fish reared at 11 psu salinity. Concomitantly, oxygen consumption was low in fish reared at 11 psu salinity. The feed conversion ratio (FCR) was lower in fish reared at 5 psu and 11 psu salinities than at 22 psu and 34 psu salinities. However, the specific growth rate (SGR) was higher in fish reared at 11 psu salinity. These results suggest that rearing fish at 11 psu salinity would decrease energy consumption for respiration and improve food-conversion efficiency. Among fish reared at 11 psu salinity, the transcript levels of growth hormone (gh) in the pituitary, as well as its receptor (ghr) and insulin-like growth factor I (igf-1) in the liver, were upregulated; these findings suggested stimulation of the growth axis at low salinity. In contrast, there were minimal differences in the transcript levels of neuropeptide Y (npy) and pro-opiomelanocortin (pomc) in the brains of fish reared at any salinity, suggesting that salinity does not affect appetite. Therefore, growth performance is higher in fish reared at 11 psu salinity because of activation of the GH-IGF system, but not appetite, in Malabar grouper juveniles.

Climate change-related warming-induced shifts in leaf chemical traits favor nutrition of the specialist herbivore Battus polydamas archidamas

One of the major impacts of climate change is increasing global temperatures. Because warming is expected to affect plant morphological and chemical traits, it may therefore also influence plant interactions with other trophic levels, including herbivores. Here, we simulated a climate warming scenario of +2.7°C in the field using open-top chambers and assessed the effects of warming on plant performance (growth, leaf area, and chlorophyll), leaf nutrients (nitrogen and carbon), and primary (amino acids and carbohydrates) and secondary (toxic aristolochic acids) metabolites in the plantAristolochia chilensis. We performed untargeted metabolomics analyses for estimating general changes in foliar metabolites between ambient control and warming-treated plants. Bioassays were additionally conducted to evaluate how changes in host plant chemistry affected growth and nutritional parameters in first-instar larvae of the specialist lepidopteran herbivoreBattus polydamas archidamas. We found that warming did not significantly affect plant performance, but did result in significant changes in leaf nutrients, and primary and secondary metabolites, although in opposite directions. While primary metabolites (specifically, nitrogen-containing compounds) decreased in response to treatment, aristolochic acids increased. Untargeted metabolomics analyses showed that, of a total of 824 features, 50 were significantly different between ambient control and warming-treated plants; some of these were identified by MS/MS spectra as amino acids. Larvae feeding on warming-treated plants, showed significantly enhanced growth, food conversion efficiency, and lipid concentration. Our study contributes to current understanding of climate change impacts on trophic interactions, showing that projected temperature increases lead to changes in the resistance phenotype of the host plant, favoring nutrition and growth of a unique specialist herbivore.