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The environment surrounding invertebrates can influence the physiology of larval offspring. Dung beetles provide several significant ecological functions, including dung breakdown, fly control and nutrient cycling. Cattle diet influences the chemical and physical constituents of dung, of which pH is considered critical. Few studies have assessed this, though a pH of 6.3 is the lowest threshold for dung beetle reproduction. We investigated the effects of an introduced and widespread dung beetle (Onthophagus binodis) on cattle dung pH (7.3, 6.0 and 5.0) and pH on O. binodis reproduction, offspring phenotypic traits and development time. Dung beetle presence increased the Δ pH (more alkaline) within dung pads after 96 h. Dung beetles produced broods in dung with a pH of 5.0, though in fewer numbers compared with the other pH treatments. Larval development was delayed in pH 5.0 with an average of 50 days compared with 44 days in dung with pH 6, 7, and the control (7.3). Smaller broods (ellipsoid volume [mm3]) were produced in dung with a pH of 5.0 compared with pH 6.0 and 7.0, and offspring emerging from broods produced from dung with a pH of 6.0 were larger compared with the other pH treatments. Our results show that dung pH is important for brood production and progeny phenotypic traits of O. binodis, an agricultural ecosystem engineer and that there is no experimental evidence to support the suggestion that dung pH influences the provisioning of broods in this species. [ABSTRACT FROM AUTHOR]

The black soldier fly, Hermetia illucens L. (Diptera: Stratiomyidae), is commonly used for organic waste recycling and animal feed production. However, the often inadequate nutrients in organic waste necessitate nutritional enhancement of black soldier fly larvae, e.g. by fungal supplementation of its diet. We investigated the amino acid composition of two fungi, Candida tropicalis (Castell.) Berkhout (Saccharomycetales: Saccharomycetaceae) and Pichia kudriavzevii Boidin, Pignal & Besson (Saccharomycetales: Pichiaceae), from the black soldier fly gut, and commercial baker's yeast, Saccharomyces cerevisiae Meyen ex E.C. Hansen (Saccharomycetales: Saccharomycetaceae), and their effects on larval growth and hemolymph metabolites in fifth-instar black soldier fly larvae. Liquid chromatography–mass spectrometry was used to study the effect of fungal metabolites on black soldier fly larval metabolism. Amino acid analysis revealed significant variation among the fungi. Fungal supplementation led to increased larval body mass and differential metabolite accumulation. The three fungal species caused distinct metabolic changes, with each over-accumulating and down-accumulating various metabolites. We identified significant alteration of histidine metabolism, aminoacyl-tRNA biosynthesis, and glycerophospholipid metabolism in BSF larvae treated with C. tropicalis. Treatment with P. kudriavzevii affected histidine metabolism and citrate cycle metabolites, while both P. kudriavzevii and S. cerevisiae treatments impacted tyrosine metabolism. Treatment with S. cerevisiae resulted in down-accumulation of metabolites related to glycine, serine, and threonine metabolism. This study suggests that adding fungi to the larval diet significantly affects black soldier fly larval metabolomics. Further research is needed to understand how individual amino acids and their metabolites contributed by fungi affect black soldier fly larval physiology, growth, and development, to elucidate the interaction between fungal nutrients and black soldier fly physiology. [ABSTRACT FROM AUTHOR]

Objective: The Blackbanded Sunfish Enneacanthus chaetodon is a small centrarchid that is endemic to slow‐moving waters from New Jersey to central Florida, United States. The distribution of this species has been increasingly fragmented, primarily due to habitat degradation. The development of larval culture protocols is essential to produce this species for the aquarium trade and for potential restoration efforts. To streamline the production process, larvae should be transitioned from live feeds to inert diets as early as possible without sacrificing larval growth or survival. Methods: A developmental trial was conducted to determine the timing of digestive tract maturation, which indicates the ability of larvae to better digest inert microdiets (MDs). Blackbanded Sunfish larvae were sampled 12 times from 2 days posthatch (dph; notochord length [mean ± SD] = 4.38 ± 0.22 mm) to 50 dph (total length [TL] = 9.89 ± 1.64 mm) for subsequent analysis of digestive enzyme activity (via microplate assays) and digestive system morphology (via histology). A dietetics trial was conducted to determine the most appropriate commercial MD for this species at early life stages by testing the efficacy of three different MDs against a reference diet of brine shrimp Artemia nauplii. Lastly, a weaning trial was conducted to determine the earliest time point at which MDs should be introduced during the larval period. Result: Blackbanded Sunfish larvae transitioned from agastric to gastric digestion at approximately 40 dph (7.95 ± 0.86 mm TL), as determined by the presence of gastric glands and pepsin activity. In the dietetics trial, certain MDs yielded higher survival than others; however, all diets performed equally when considering the TL of the larvae. In the weaning trial, the highest survival was found when larvae were fed Artemia nauplii exclusively or when an MD was introduced at 48 dph (10.62 ± 1.88 mm TL). Conclusion: Larval Blackbanded Sunfish may require up to 48 days of live feeds before introducing MDs but can be successfully transitioned to MDs after 48 dph without significantly affecting survival or growth. Impact statementThe Blackbanded Sunfish, a species with threatened populations throughout its endemic range, can be successfully aquacultured to aid in potential population restoration initiatives or to supply fish for the aquarium trade. [ABSTRACT FROM AUTHOR]

Mosquito-borne diseases account for nearly 1 million human deaths annually, yet we have a limited understanding of developmental events that influence host-seeking behavior and pathogen transmission in mosquitoes. Mosquito-borne pathogens are transmitted during blood meals, hence adult mosquito behavior and physiology have been intensely studied. However, events during larval development shape adult traits, larvae respond to many of the same sensory cues as adults, and larvae are susceptible to infection by many of the same disease-causing agents as adults. Hence, a better understanding of larval physiology will directly inform our understanding of physiological processes in adults. Here, we use single cell RNA sequencing (scRNA-seq) to provide a comprehensive view of cellular composition in the Aedes aegypti larval ventral nerve cord (VNC), a central hub of sensory inputs and motor outputs which additionally controls multiple aspects of larval physiology. We identify more than 35 VNC cell types defined in part by neurotransmitter and neuropeptide expression. We also explore diversity among monoaminergic and peptidergic neurons that likely control key elements of larval physiology and developmental timing, and identify neuroblasts and immature neurons, providing a view of neuronal differentiation in the VNC. Finally, we find that larval cell composition, number, and position are preserved in the adult abdominal VNC, suggesting studies of larval VNC form and function will likely directly inform our understanding adult mosquito physiology. Altogether, these studies provide a framework for targeted analysis of VNC development and neuronal function in Aedes aegypti larvae. [ABSTRACT FROM AUTHOR]

Early life survival is critical to successful replenishment of fish populations, and hypotheses developed under the Growth‐Survival Paradigm (GSP) have guided investigations of controlling processes. The GSP postulates that recruitment depends on growth and mortality rates during early life stages, as well as their duration, after which the mortality declines substantially. The GSP predicts a shift in the frequency distribution of growth histories with age towards faster growth rates relative to the initial population because slow‐growing individuals are subject to high mortality (via starvation and predation). However, mortality data compiled from 387 cases published in 153 studies (1971–2022) showed that the GSP was only supported in 56% of cases. Selection against slow growth occurred in two‐thirds of field studies, leaving a non‐negligible fraction of cases showing either an absence of or inverse growth‐selective survival, suggesting the growth‐survival relationship is more complex than currently considered within the GSP framework. Stochastic simulations allowed us to assess the influence of key intrinsic and extrinsic factors on the characteristics of surviving larvae and identify knowledge gaps on the drivers of variability in growth‐selective survival. We suggest caution when interpreting patterns of growth selection because changes in variance and autocorrelation of individual growth rates among cohorts can invalidate fundamental GSP assumptions. We argue that breakthroughs in recruitment research require a comprehensive, population‐specific characterization of the role of predation and intrinsic factors in driving variability in the distribution and autocorrelation of larval growth rates, and of the life stage corresponding to the endpoint of pre‐recruited life. [ABSTRACT FROM AUTHOR]

Temperature and food quality are the most important environmental factors determining the performance of herbivorous insects. The objective of our study was to evaluate the responses of the spongy moth (formerly known as the gypsy moth) [Lymantria dispar L. (Lepidoptera: Erebidae)] to simultaneous variation in these two factors. From hatching to the fourth instar, larvae were exposed to three temperatures (19 °C, 23 °C, and 28 °C) and fed four artificial diets that differed in protein (P) and carbohydrate (C) content. Within each temperature regime, the effects of the nutrient content (P+C) and ratio (P:C) on development duration, larval mass, growth rate, and activities of digestive proteases, carbohydrases, and lipase were examined. It was found that temperature and food quality had a significant effect on the fitness-related traits and digestive physiology of the larvae. The greatest mass and highest growth rate were obtained at 28 °C on a high-protein low-carbohydrate diet. A homeostatic increase in activity was observed for total protease, trypsin, and amylase in response to low substrate levels in the diet. A significant modulation of overall enzyme activities in response to 28 °C was detected only with a low diet quality. A decrease in the nutrient content and P:C ratio only affected the coordination of enzyme activities at 28 °C, as indicated by the significantly altered correlation matrices. Multiple linear regression analysis showed that variation in fitness traits in response to different rearing conditions could be explained by variation in digestion. Our results contribute to the understanding of the role of digestive enzymes in post-ingestive nutrient balancing. [ABSTRACT FROM AUTHOR]

Objective: Insect pests can cause severe losses in oilseed rape yields across Europe. Genomic and transcriptomic information is very limited for these insects. The aim of our study was to provide transcriptomic resources on several oilseed rape herbivores that will support research into their biology and help develop new methods of sustainable pest management. Data: Transcriptomes for larval stages of five major European pest species were de novo assembled by Trinity assembler. Total number of transcripts ranged from 112,247 for Ceutorhynchus pallidactylus to 225,110 for Ceutorhyncus napi. Intermediate numbers of 140,588, 140,998 and 144,504, were found for Psylliodes chrysocephala, Dasineura brassicae, and Brassicogethes aeneus, respectively. Bench-marking universal single-copy orthologues analyses for each dataset indicated high degree of completeness for all five species. The transcriptomes extend the list of genomic data on insect larvae that constitute major pests of oilseed rape. The data provide information on larval physiology and form a basis to develop highly specific RNA interference-based plant protection. [ABSTRACT FROM AUTHOR]

Terrestrial nutrients flushed to sea via coastal runoff may provide a trophic subsidy to filter‐feeders, which might be particularly relevant in oligotrophic waters. In this study, we investigated how allochthonous subsidies might modulate the settlement dynamics of the mytilid Brachidontes solisianus, a space monopoliser in subtropical Brazilian shores. We used fatty acid trophic markers to identify the dietary subsidies to nearshore waters during wet and dry periods, and integrated them with key ecological drivers (temperature, rainfall) and physiological factors (nutritional status, size at settlement) acting on early life stages. Like other mytilids, for B. solisianus primary settlement can be followed by resuspension and reattachment (secondary settlement). A higher share of primary settlers may signal localized recruitment, while a larger contribution of secondary settlers would indicate increased migration rates. Through redundancy analyses we found that rainfall was correlated with 1) nearshore fatty acid trophic markers of land origin and 2) the frequency of primary settlers during the wet period, when the share of terrestrial inputs was also highest (13% of nearshore suspended matter). Conditions appeared favorable to localized recruitment through trophic settlement triggers, as settlement pulses of pelagic drifters followed heavy rains. Further, lipid analyses of pediveligers revealed that during the dry period these competent larvae selectively incorporated the essential 22:6ω3 docosahexaenoic acid (DHA) into membrane phospholipids at the expense of reserve lipids, suggesting a dietary deficit. Secondary dispersal also prevailed, indicating that the chance for relocation through secondary migrations during dry periods is likely higher. Overall, our results suggest that coastal runoff leads to allochthonous trophic subsidies in the form of organic‐rich plumes which may strongly modulate the settlement rate and dispersal potential of B. solisianus. Subsidies from land to coastal waters may thus be critical for the stability of benthic communities in regions of low marine primary production. [ABSTRACT FROM AUTHOR]

Mitochondrial function depends on direct interactions between respiratory proteins encoded by genes in two genomes, mitochondrial and nuclear, which evolve in very different ways. Serious incompatibilities between these genomes can have severe effects on development, fitness and viability. The effect of subtle mitonuclear mismatches has received less attention, especially when subject to mild physiological stress. Here, we investigate how two distinct physiological stresses, metabolic stress (high-protein diet) and redox stress [the glutathione precursor N-acetyl cysteine (NAC)], affect development time, egg-to-adult viability, and the mitochondrial physiology of Drosophila larvae with an isogenic nuclear background set against three mitochondrial DNA (mtDNA) haplotypes: one coevolved (WT) and two slightly mismatched (COX and BAR). Larvae fed the high-protein diet developed faster and had greater viability in all haplotypes. The opposite was true of NAC-fed flies, especially those with the COX haplotype. Unexpectedly, the slightly mismatched BAR larvae developed fastest and were the most viable on both treatments, as well as control diets. These changes in larval development were linked to a shift to complex I-driven mitochondrial respiration in all haplotypes on the high-protein diet. In contrast, NAC increased respiration in COX larvae but drove a shift toward oxidation of proline and succinate. The flux of reactive oxygen species was increased in COX larvae treated with NAC and was associated with an increase in mtDNA copy number. Our results support the notion that subtle mitonuclear mismatches can lead to diverging responses to mild physiological stress, undermining fitness in some cases, but surprisingly improving outcomes in other ostensibly mismatched fly lines. [ABSTRACT FROM AUTHOR]

In the present study, the digestive enzyme activity during larval development in L. peru reared under intensive culture conditions was evaluated. The results revealed that L. peru larvae have the necessary enzymes to digest proteins, lipids and carbohydrates when nutritional reserves have been depleted at the onset of the exogenous feeding at 3 days after hatching (DAH) or 78 degree‐days (DD). The activities of the digestive enzymes follow patterns similar to those previously reported in other related species. As in other marine fish larvae, the amylase specific activity decreased during larval development of L. peru. At 25 DAH (650 DD), the specific activities of lipase, alkaline phosphatase and acid phosphatase declined, while the specific activities of pepsin, trypsin and chymotrypsin increased. In contrast, the individual activity of all enzymes steadily increased with development. The time required to reach the maximum activity varies, suggesting a relative importance of different digestive enzymes during the different developmental stages of the digestive tract. In our study, the highest activity was reached by amylase at Stage I and early Stage II (3–11 DAH or 78–286 DD), by lipase and both acid and alkaline phosphatases at the end of Stage II (18–22 DAH or 468–572 DD), and by trypsin, chymotrypsin and acid protease at Stage III (25 DAH or 650 DD). This study provides new data on the digestive physiology of larval L. peru that are particularly pertinent to early weaning and nutritional physiology, and that may be useful in the larval culture of this species. [ABSTRACT FROM AUTHOR]

Life histories of species may be shaped by nutritional limitations posed on populations. Yet, populations contain individuals that differ according to sex and life stage, each of which having different nutritional demands and experiencing specific limitations. We studied patterns of resource assimilation, allocation and excretion during the growth of the solitary bee Osmia bicornis (two sexes) under natural conditions. Adopting an ecological perspective, we assert that organisms ingest mutable organic molecules that are transformed during physiological processes and that the immutable atoms of the chemical elements composing these molecules may be allocated to specific functions, thereby influencing organismal fitness and life history. Therefore, using the framework of ecological stoichiometry, we investigated the multielemental (C, N, S, P, K, Na, Ca, Mg, Fe, Zn, Mn, Cu) compositions of six components of the bee elemental budget: food (pollen), eggs, pupae, adults, cocoons and excreta. The sexes differed fundamentally in the assimilation and allocation of acquired atoms, elemental phenotypes, and stoichiometric niches for all six components. Phosphorus, which supports larval growth, was allocated mainly (55–75%) to the cocoon after larval development was complete. Additionally, the majority (60–99%) of the Mn, Ca, Mg and Zn acquired during larval development was allocated to the cocoon, probably influencing bee fitness by conferring protection. We conclude that for holometabolous insects, considering only the chemical composition of the adult body within the context of nutritional ecology does not provide a complete picture. Low ratios of C to other nutrients, low N:P and high Na concentrations in excreta and cocoons may be important for local-scale nutrient cycling. Limited access to specific nutritional elements may hinder bee development in a sex-dependent manner, and N and P limitations, commonly considered elsewhere, may not play important roles in O. bicornis. Sexual dimorphism in nutritional limitations due to nutrient scarcity during the larval stage may influence bee population function and should be considered in bee conservation efforts. [ABSTRACT FROM AUTHOR]

Physiological biomarkers are commonly used to assess the health of taxa exposed to natural and anthropogenic stressors. Glucocorticoid (GC) hormones are often used as indicators of physiological stress in wildlife because they affect growth, reproduction and survival. Increased salinity from human activities negatively influences amphibians and their corticosterone (CORT; the main amphibian GC) physiology; therefore, CORT could be a useful biomarker. We evaluated whether waterborne CORT could serve as a biomarker of salt stress for three free-living amphibian species that vary in their sensitivity to salinity: boreal chorus frogs (Pseudacris maculata), northern leopard frogs (Rana pipiens) and barred tiger salamanders (Ambystoma mavortium). Across a gradient of contamination from energy-related saline wastewaters, we tested the effects of salinity on baseline and stress-induced waterborne CORT of larvae. Stress-induced, but not baseline, CORT of leopard frogs increased with increasing salinity. Salinity was not associated with baseline or stress-induced CORT of chorus frogs or tiger salamanders. Associations between CORT and salinity were also not related to species-specific sensitivities to salinity. However, we detected background environmental CORT (ambient CORT) in all wetlands and spatial variation was high within and among wetlands. Higher ambient CORT was associated with lower waterborne CORT of larvae in wetlands. Therefore, ambient CORT likely confounded associations between waterborne CORT and salinity in our analysis and possibly influenced physiology of larvae. We hypothesize that larvae may passively take up CORT from their environment and downregulate endogenous CORT. Although effects of some hormones (e.g. oestrogen) and endocrine disruptors on aquatic organisms are well described, studies investigating the occurrence and effects of ambient CORT are limited. We provide suggestions to improve collection methods, reduce variability and avoid confounding effects of ambient CORT. By making changes to methodology, waterborne CORT could still be a promising, non-invasive conservation tool to evaluate effects of salinity on amphibians. [ABSTRACT FROM AUTHOR]

The aim of the present study is to investigate spawning and larval rearing of brown meagre (Sciaena umbra). This is an important species in the Mediterranean Sea because of its beauty, calm swimming, large otoliths, souvenir potential, aggregative behaviour, excellent flesh and accessibility. Although this species is regarded as Near Threatened (in IUCN Red List Status), the demand increases the fishing. Green water technique was used for rearing the brown meagre larvae. Diameter of eggs was recorded as 1457.31±47.29 μm. Yolk was homogenous with oil globules of 371.59±18.15 μm at the centre. Hatching process began after 39 hours. Hatching rate (HR) was observed as 92.17±0.24%, and larvae inflated swim bladder around 97.33±0.94%. The brown meagre juveniles reached to 40.08±1.98 mm of total length (TL) with 10.96±0.08 mm body height (BH) and 662.27±21.23 mg body weight (BW) after 55 days of post-hatching. Survival (SR) was recorded as 72.5±0.70% at the end of study. Since the brown meagre is a threatened species, with high economic interest, is a possible candidate for commercial aquaculture both food and restocking the depleted natural fisheries. [ABSTRACT FROM AUTHOR]

Yellow genes are thought to be involved in the melanin biosynthetic pathway and play a crucial role in pigmentation reactions in insects. However, little research has been done on yellow genes in lepidopteran pests. To clarify the function of one of the yellow genes (yellow-y) in Spodoptera litura , we cloned the full-length of yellow-y , and investigated its spatial and temporal expression profiles by quantitative real-time PCR (qPCR). It revealed that yellow-y was highly expressed in larva of fourth, fifth, and sixth instars, as well as in epidermis (Ep), fat bodies (FB), Malpighian tubes (MT), and midguts (MG) of the larvae; whereas it was expressed in very low levels in different tissues of adults, and was almost undetected in pupa. This expression profile suggests an important role of yellow-y in larvae, minor role in adults, and no role in pupae. To confirm this, we disrupted yellow-y using the clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) system, and obtained G0 insects with mutation in yellow-y. The mutation in yellow-y clearly rendered the larvae body, a color yellower than that of wide type insects, and in addition, the mutation resulted in abnormal segmentation and molting for older larvae. The mutation of yellow-y also made various adult tissues (antennae, proboscis, legs, and wings) yellowish. However, the mutation had no effect on pigmentation of the pupal cuticle. Taken together, our study clearly demonstrated the role of yellow-y not only in the body pigmentation of larvae and adults, and but also in segmentation and molting of larvae, providing new insights into the physiology of larval development, as well as a useful marker gene for genome editing based studies. [ABSTRACT FROM AUTHOR]

As in mammals, high-sucrose diets lead to obesity and insulin resistance in the model organism Drosophila melanogaster (called Drosophila hereafter). To explore the relative contributions of glucose and fructose, sucrose’s component monosaccharides, we compared their effects on larval physiology. Both sugars exhibited similar effects to sucrose, leading to obesity and hyperglycemia. There were no striking differences resulting from larvae fed high glucose versus high fructose. Some small but statistically significant differences in weight and gene expression were observed that suggest Drosophila is a promising model system for understanding monosaccharide-specific effects on metabolic homeostasis. [ABSTRACT FROM AUTHOR]

Spatio‐temporal variation in aquatic habitat characteristics can have important implications for the population and community dynamics of organisms utilizing these habitats. We studied the life‐history responses of Culex pipiens larvae (Diptera: Culicidae) to multiple environmental factors associated with habitat drying by increasing larval density (directly affecting resource availability), temperature fluctuations (influencing physiological processes), and solute concentration due to evaporation (inducing an environmental stress), using a full‐factorial design. We found that high density led to lower larval survival and to shorter development time. Larvae delayed their metamorphosis in response to fluctuating temperature. We detected inter‐sexual differences in the effects of these two factors on adult body sizes, with high larval density leading to the emergence of smaller females, and fluctuating temperature translating to larger adult males. The two sexes also differed concerning the two‐way interactive effects of different environmental factors on development time and on adult size. Our findings indicate that C. pipiens larvae respond to multiple environmental factors via phenotypic plasticity, rather than through bet‐hedging. Future studies should account for additional inter‐stage effects, rather than body size, such as adult fecundity, longevity, and dispersal. Life history traits are influenced by both biotic and abiotic conditions and by the degree to which these environmental factors vary in space and over time. Here we show that larvae of the common house mosquito display interactive and sex‐specific life‐history responses to multiple environmental factors associated with the drying of their aquatic habitats. Such responses can have important implications for the population dynamics of the common house mosquito, and for the various diseases it can potentiality transmit. [ABSTRACT FROM AUTHOR]

As the main agricultural insect pollinator, the honey bee (Apis mellifera) is exposed to a number of agrochemicals, including glyphosate (GLY), the most widely used herbicide. Actually, GLY has been detected in honey and bee pollen baskets. However, its impact on the honey bee brood is poorly explored. Therefore, we assessed the effects of GLY on larval development under chronic exposure during in vitro rearing. Even though this procedure does not account for social compensatory mechanisms such as brood care by adult workers, it allows us to control the herbicide dose, homogenize nutrition and minimize environmental stress. Our results show that brood fed with food containing GLY traces (1.25–5.0 mg per litre of food) had a higher proportion of larvae with delayed moulting and reduced weight. Our assessment also indicates a non-monotonic dose-response and variability in the effects among colonies. Differences in genetic diversity could explain the variation in susceptibility to GLY. Accordingly, the transcription of immune/detoxifying genes in the guts of larvae exposed to GLY was variably regulated among the colonies studied. Consequently, under laboratory conditions, the response of honey bees to GLY indicates that it is a stressor that affects larval development depending on individual and colony susceptibility. [ABSTRACT FROM AUTHOR]

The potential of teflubenzuron was assessed in a series of laboratory studies in order to achieve consistent, long-term, integrated management of the Colorado potato beetle, Leptinotarsa decemlineata (Say). Teflubenzuron exhibited excellent stomach toxicity to the larvae. Its larvicidal activity was comparable with those of cyhalothrin, chlorantraniliprole and spinosad. Moreover, the teflubenzuron-fed larvae consumed less foliage, grew slower, and needed a longer period to develop, in a dose dependent manner. Most of these larvae died during larval-larval molting, larval-pupal ecdysis or adult emergence. Furthermore, chitin contents in body carcass (without midgut) and integument specimen of the teflubenzuron-fed larvae significantly decreased, whereas the chitin amount in the midgut peritrophic matrix was not affected. In addition, uridine diphosphate-N-acetylglucosamine-pyrophosphorylase gene (LdUAP1), which was mainly responsible for chitin biosynthesis in ectodermally-derived tissues, was suppressed after teflubenzuron ingestion, in contrast to its partner LdUAP2 for chitin formation in the midgut peritrophic matrix. In a word, by inhibition of chitin production in ectodermally-derived tissues, teflubenzuron is an effective benzoylurea insecticide to L. decemlineata larvae. It can be a valuable tool in effective integrated pest management and insecticide resistance management programs against L. decemlineata. [ABSTRACT FROM AUTHOR]

Abstract: The spatial distribution of relatives has profound effects on kin interactions, inbreeding, and inclusive fitness. Yet, in the marine environment, the processes that generate patterns of kin structure remain understudied because larval dispersal on ocean currents was historically assumed to disrupt kin associations. Recent genetic evidence of co‐occurring siblings challenges this assumption and raises the intriguing question of how siblings are found together after a (potentially) disruptive larval phase. Here, we develop individual‐based models to explore how stochastic processes operating at the individual level affect expected kinship at equilibrium. Specifically, we predict how limited dispersal, sibling cohesion, and variability in reproductive success differentially affect patterns of kin structure. All three mechanisms increase mean kinship within populations, but their spatial effects are markedly different. We find that (1) when dispersal is limited, kinship declines monotonically as a function of the distance between individuals; (2) when siblings disperse cohesively, kinship increases within a site relative to between sites; and (3) when reproductive success varies, kinship increases equally at all distances. The differential effects of these processes therefore only become apparent when individuals are sampled at multiple spatial scales. Notably, our models suggest that aggregative larval behaviors, such as sibling cohesion, are not necessary to explain documented levels of relatedness within marine populations. Together, these findings establish a theoretical framework for disentangling the drivers of marine kin structure. [ABSTRACT FROM AUTHOR]

In this article, we report on the development and growth of alpine chironomid species in a highly glaciated headwater, using biometrical analyses. Glacially influenced alpine streams are characterized by year-round harsh environmental conditions. Only a few, highly adapted benthic insects, mainly chironomid larvae (genus Diamesa) live in these extreme conditions. Although several studies have shown patterns in ecosystem structure and function in alpine streams, cause-effect relationships of abiotic components on aquatic insects’ life strategies are still unknown. Sampling was performed at Schlatenbach, a river draining the Schlatenkees (Hohe Tauern NP, Austria), at three sites and on six occasions from August to October 2015. Semi-quantitatively sampled Diamesa cinerella (Meigen 1835) and Diamesa steinboecki (Goetghebuer 1933) larvae were biometrically analysed, and they showed differences in larval size and biovolume with higher values close to the glacier. Considering the decreasing water temperatures but increasing benthic organic matter towards the glacier, food availability seems to play a crucial role for larval size in highly glaciated alpine headwaters. This is the first study to show that harsh conditions in these environments (low temperatures, high turbidity and flow dynamics) may exclude many taxa, but favour other, highly adapted species, when their essential needs (food quality and quantity) are guaranteed. [ABSTRACT FROM AUTHOR]

The effect of six available and commercial disinfectants on the embryonation and larval development of Toxascaris leonina eggs was studied. Dettol® and Virkon® both induced a 100% reduction in larval development (P ≤ 0.05). Dettol® resulted in deformed eggshells and a halt in embryonal development at 1 week post exposure. All Virkon®-treated eggs showed an early embryonic lysis 24 h post exposure. TH4+ and 70% ethanol both significantly (P ≤ 0.05) affected larval development, with 58.8 and 85.8% reduction, respectively. Neither sodium hypochlorite nor phenol significantly affected larval development (2.8 and 21.0%, respectively). Sodium hypochlorite treatment caused a visible decortication of the eggshell; however, phenol-treated embryonated Toxascaris eggs appeared more or less morphologically normal. In conclusion, the disinfectants tested induced variable degrees of decortication and suppression of larval development. Virkon®S was the most effective disinfectant against Toxascaris eggs, suggesting that it is the most advisable one to use. To the best of our knowledge, this is the first report of the use of Virkon®S as an ovicide and/or larvicide of helminths, particularly Toxascaris leonina. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, the hypothesis that the difference in axenic conditions in the incubation and rearing environment of European seabass larvae induces size and shape effects on the specimens is tested. This difference is studied between xenic and axenic seabass larvae of DAH (day after hatching) 0, 5, 11 and 15. The axenic rearing protocol involves an egg disinfection with glutaraldehyde after the primary one with iodine in the hatchery, and the hypothesis that this secondary disinfection induces size and shape effects is also tested. In order to accomplish this, three egg and larvae treatments are included: “DA” (disinfected axenic), “DX” (disinfected xenic) and “NX” (nondisinfected xenic). Regarding the effect of antibiotic‐induced axenity, DA larvae exhibited larger bodies than both DX and NX on DAH 5 and 11. They also had a smaller yolk sac than DX at hatching, but consumed it slower. Towards the end of the experiment, DA larvae were thicker, but slightly more curved than DX and NX, which may be an abnormal shape, or a slightly more advanced ontogenetic stage. As far as egg disinfection, it had significant but very moderate shape effects on DAH 5 and 11, and disinfected larvae consumed their yolk sac faster. To the best of our knowledge, this study is one of the first to illustrate the subtle but significant size and shape effects caused by antibiotic‐induced axenity and secondary egg disinfection in the early larval stages, which suggest the existence of bacterial mechanisms that play a phenotypic role. [ABSTRACT FROM AUTHOR]

Abstract: Survival, growth and fatty acid composition of Ostrea edulis larvae (L.) fed four different single species, microalgal diets, Tisochrysis lutea (T), Chaetoceros neogracile (Cg), Skeletonema marinoi (Sm) or Tetraselmis suecica (Ts) from broodstock to pre‐settlement, were studied. Lower larval growth (5.5 μm to 6.5 μm/d) was recorded in progeny continuously fed single S. marinoi or T. suecica, whereas good growth was achieved with single T. lutea (7.8 μm/d). Larvae, originated from broodstock receiving Sm or Ts, exhibited growth compensation when fed a bispecific balanced diet (TCg). This did not occur when broodstock and larvae were fed Cg or T, for which single or mixed diets led to similar larval growth. Furthermore, survival was high (>90%) regardless of microalgal diet, except for larvae fed from broodstock to pre‐settlement T (53%) or Ts (2%). There were significant differences in 20:5 (n‐3) and 22: 6 (n‐3) contents in polar and neutral fractions of O. edulis expelled larvae dependent on broodstock diet, as well as throughout larval development, but no clear trend was apparent when comparing fatty acid (FA) relative composition of both fractions of O. edulis larvae fed different diets at release or prior to settlement. In contrast, such correlation occurred when FA was expressed in absolute content but exclusively for larvae‐fed single diets and was particularly noticeable between 22: 6 (n‐3) and growth and survival. In the present work, broodstock nutritional deficiencies have been revealed in O. edulis progeny, compensated thereafter by feeding the larvae a mixed diet, and in this balanced condition, no obvious relation with larval development indicators was found with main fatty acid contents. [ABSTRACT FROM AUTHOR]

Abstract: Historically, the mortality of early‐life stages of marine fishes was supposed to be mostly caused by poor feeding during a critical period and aberrant drifting away from favorable recruitment areas. While fish larvae may display remarkable swimming abilities, Hjort's aberrant drift hypothesis has rarely been tested. In this study, we measured critical swimming speed (Ucrit) of settlement‐stage larvae of six coastal, warm temperate Mediterranean fish species, for which no data were previously available (Sparidae: Boops boops, Diplodus annularis, Spicara smaris, Spondyliosoma cantharus; Pomacentridae: Chromis chromis; Mugilidae sp.). Their swimming speeds were comparable with those of other temperate species, but also with the speeds of tropical species, which are considered as very fast swimmers. Mugilidae were the fastest (29.2 cm s−1), followed by Pomacentridae (22.8 cm s−1) and Sparidae (11.6 cm s−1). Most larvae swam in an inertial regime (Reynolds number > 1000). Those swimming speeds were then implemented in a Lagrangian model of the competency period of these species, set in the same area (the Ligurian Sea) and at the same time (June 2014) as the observations. In this modeling experiment, directional swimming strongly increased the proportion of successful settlers, independent of mesoscale hydrological structures. Fish larvae could settle on the coast from as far as tens of kilometers offshore, in just 4 d. These findings suggest that aberrant drift is unlikely to occur for strong swimming temperate larvae and show that larval behavior should be considered on equal footing with ocean currents when assessing larval fish dispersal. [ABSTRACT FROM AUTHOR]

Little research has been done on egg diapause and the embryonic development of water mites. The aim of this study was to check the impact of temperature and periods of light on hatching of larvae of Eylais extendens. Three batches of eggs which were spawned on 30 July were placed at one of three temperatures (4, 10 and 20 °C) and two periods of light (7 and 14 h per day). Egg hatching (both, percentage of hatched larvae and rate of hatching) was found to differ between 4 versus 10 °C and between 4 versus 20 °C, but not between 10 versus 20 °C. The periods of light had no influence on hatching. This synchronization of hatching, enabling the eggs to emerge from diapause in the spring, could be considered an evolutionary adaptation aimed at postponing hatching of late-spawned eggs until a time allowing for completion of the full development cycle, including the parasitic larval stage. [ABSTRACT FROM AUTHOR]

We report measurements of ion transport across the gastric caecum of larvae of Aedes aegypti, a vector of yellow fever that inhabits a variety of aquatic habitats ranging from freshwater to brackish water. We provide the first measurements of the effect of 5-hydroxytryptamine (5-HT) on transepithelial potential (TEP), luminal ion concentrations and electrochemical potentials, as well as basolateral membrane potential and H+, Na+ and K+ fluxes. TEP, basolateral membrane potential, and H+, K+ and Na+ fluxes across the gastric caeca declined within 3-6 min after isolation of the entire midgut from the larva. 5-HT restored both the TEP and active accumulation of H+, K+ and Na+ in the lumen. Additionally, 5-HT restored H+, K+ and Na+ fluxes across the distal caecum of freshwater larvae, and restored H+ fluxes across the distal caecum of brackish water larvae. There was no effect of 5-HT on ion fluxes across the proximal caecum.We have also shown that 5-HT restores the basolateral membrane potential in cells of the distal, but not proximal, caecum. Effects of 5-HT on TEP and basolateral membrane potential were mimicked by application of cAMP but not by a phorbol ester. We provide a working model which proposes that 5-HT and cAMP stimulate the vacuolar H+-ATPase of the distal caecum. Our results provide evidence that the gastric caecum is functionally distinct from the adjacent anterior midgut and we discuss possible roles of the gastric caecum in osmoregulation. We also describe similarities in the arrangement of ion transporters in the caecum with those of the Malpighian tubules. [ABSTRACT FROM AUTHOR]

Although Fejervarya kawamurai is a common frog in the paddies of western Japan, their larvae seem to be scarce in the paddies where larvae of Hyla japonica and Pelophylcix nigromaculatus are abundant. To examine the cause of this phenomenon, we surveyed the reproductive season of these three species at two sites with different irrigation schedules using an automatic recording system. In addition, we conducted several experiments to test three possible explanations;(1)maternal avoidance from P. nigromaculatus larvae in the selection of oviposition site, (2) predation on F. kawamurai eggs by P. nigromaculatus and the larvae of other species, and (3) negative interactions of P. nigromaculatus larvae on the larvae of F. kawamurai. In paddies flooded throughout the year, calling of H. japonica and P. nigromaculatus started far earlier than in F. kawamurai, whereas in paddies irrigated in mid-May, these three species started calling simultaneously. We found significant predation pressures on F. kawamurai eggs from larvae of H. japonica, Rcinci japonica, P. nigromaculatus, P. porosus bi.evipodus, Glandircina rugosa, F. kawamurai, and Rhacophorus schlegelii, whereas no significant predation pressures from larvae of B. japonicus was detected. We found no evidence of maternal choice by F. kawamurai for oviposition sites and no effects of F. nigromaculatus larvae on sympatric larvae of F. kawamurai. Our results suggest the possibility that the mortality rate of F. kawamurai eggs might increase through predation at paddies where H. japonica and P. nigromaculatus start oviposition earlier than does F. kawamurai. [ABSTRACT FROM AUTHOR]

Gut microbes positively affect the physiology of many animals, but the molecular mechanisms underlying these benefits remain poorly understood. We recently reported that bacteria-induced gut hypoxia functions as a signal for growth and molting of the mosquito Aedes aegypti. In this study, we tested the hypothesis that transduction of a gut hypoxia signal requires hypoxia-induced transcription factors (HIFs). Expression studies showed that HIF-α was stabilized in larvae containing bacteria that induce gut hypoxia but was destabilized in larvae that exhibit normoxia. However, we could rescue growth of larvae exhibiting gut normoxia by treating them with a prolyl hydroxylase inhibitor, FG-4592, that stabilized HIF-α, and inhibit growth of larvae exhibiting gut hypoxia by treating them with an inhibitor, PX-478' that destabilized HIF-α. Using these tools, we determined that HIF signaling activated the insulin/insulin growth factor pathway plus select mitogen-activated kinases and inhibited the adenosine monophosphate-activated protein kinase pathway. HIF signaling was also required for growth of the larval midgut and storage of neutral lipids by the fat body. Altogether, our results indicate that gut hypoxia and HIF signaling activate multiple processes in A. aegypti larvae, with conserved functions in growth and metabolism. [ABSTRACT FROM AUTHOR]

Carbon capture and storage has become a new mitigation option to reduce anthropogenic CO2emissions. The effects of the CO2-related acidification, associated with unpredictable leaks of CO2during the operational phases were studied using theParacentrotus lividussea urchin-liquid-phase-assays (fertilisation and embryo-larval development tests). Besides to the direct effects of the CO2-associated pH decrease, the possible effects on marine sediment toxicity were studied by exposing the urchin larvae to elutriate of sediments with different metals concentration, which were subjected to various pH treatments. The resulted median toxic effect pH ranged from 6.33 ± 0.02 and 6.91 ± 0.01 for the egg fertilisation, and between 6.66 ± 0.03 and 7.16 ± 0.01 for the larval development assays. Concentrations of Co, Zn, As, Cu, and Fe were detected in the sediment elutriates. For all the sediment elutriates tested the amount of the dissolved Zn increased in parallel with the pH reductions. Correlated effects of acidification, biological response, and the presence of dissolved metals were observed in this work evidencing that the most important factor controlling the reduction of egg fertilisation and larval development success was the combined effects of the reduction of pH and the presence of the contaminants (mainly Zn, Co, and As). [ABSTRACT FROM PUBLISHER]

Copyright of Jornal of Al-Muthanna for Agricultural Sciences is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Hatchery production of great scallop, Pecten maximus, remains unpredictable, notably due to poor larval survival. Large-scale flow-through systems up to 3500 L have been developed to avoid the use of antibiotics in static systems. Alternatively, small-scale flow-through systems have been successfully applied for oysters but they proved to be unsuitable to rear scallop larvae. By focusing on physical factors presumed to limit P. maximus larval development, this study aimed to optimize great scallop larvae rearing parameters under controlled conditions. First, the influence of aeration on larval performances, energetic metabolism and antioxidant defences were studied both in static and flow-through systems. Aeration depressed larval food intake, regardless of the intensities of flow tested (100 ml/min, 155 ml/min and 270 ml/min). On the other hand, antioxidant enzyme activities remained constant or decreased, suggesting that antioxidant defences were inactivated. The increase in citrate synthase activity suggested an increase in metabolic rate possibly due to a turbulent stressful environment. All larvae exposed to such turbulence died before reaching metamorphosis, whereas those reared without aeration survived well (≈ 95%). The effects of water renewal were thereafter studied in 50-L flow-through flat-bottomed tanks. No differences in survival (20.4 ± 0.5%), growth (3.8 ± 0.2 μm/d), competence (5.6 ± 0.2%), energetic metabolism level and antioxidant enzyme activities were observed when comparing 12.5 and 25 L/hr water renewal. Whereas air bubbling leads to detrimental effects, flow-through in small flat-bottomed tanks appears to be a suitable technique for scallop larvae rearing. [ABSTRACT FROM AUTHOR]

Controlled incorporation of selected microalgae and bacteria in aquaculture systems can be beneficial because they can act as microbiological control. That is why the characteristics of biofilm generated naturally in Seriola lalandi culture cages were analysed, their potential benefit to the growth of larvae was studied, and their controlled use for improving the larval viability and as a vector to improve incorporation of previously studied probiotic bacteria was tested. According to biodiversity results, these biofilms are composed of a diatom-bacteria mix showing a decrease in biodiversity in laboratory culture conditions being dominated by Navicula phyllepta and bacteria of the family Rhodobacteraceae. This can be produced on mesh substrates incorporated in bioreactors with rapid growth rate and adhesiveness. Preliminary results from the addition of substrates with this specific biofilm in larvae culture systems showed that it is consumed by the larvae without negative effects, while positive effects on the viability of larvae in combination with probiotics were observed. Considering preliminary results, the addition of these specific substrates with diatom-bacteria biofilms could be a good improvement for aquaculture systems and together with the use of probiotics can contribute to maintaining a stable and controlled system improving the viability of the larval fish culture in its early stages. [ABSTRACT FROM AUTHOR]

Nervous system organization differs greatly in larvae and adults of many species, but has nevertheless been traditionally used for phylogenetic studies. In phoronids, the organization of the larval nervous system depends on the type of development. With the goal of understanding the ground plan of the nervous system in phoronid larvae, the development and organization of the larval nervous system were studied in a viviparous phoronid species. The ground plan of the phoronid larval nervous system includes an apical organ, a continuous nerve tract under the preoral and postoral ciliated bands, and two lateral nerves extending between the apical organ and the nerve tract. A bilobed larva with such an organization of the nervous system is suggested to be the primary larva of the taxonomic group Brachiozoa, which includes the phyla Brachiopoda and Phoronida. The ground plan of the nervous system of phoronid larvae is similar to that of the early larvae of annelids and of some deuterostomians. The protostome- and deuterostome-like features, which are characteristic of many organ systems in phoronids, were probably inherited by phoronids from the last common bilaterian ancestor. The information provided here on the ground plan of the larval nervous system should be useful for future analyses of phoronid phylogeny and evolution. [ABSTRACT FROM AUTHOR]

Vertical distribution of planktonic larvae affects their passive horizontal transport. We investigated vertical distributions of ark shell Arcidae species larvae at successive developmental stages monthly from August to October 2009 along axial transects in Sendai Bay, an open embayment along the Pacific coast of northeastern Japan, where the ark shell Anadara broughtonii (Schrenck 1867) is the dominant arcid species. Younger larvae (early and mid-umbo stages) were typically distributed in the surface near the shore with salinity <33 psu. Older larvae (late umbo and competent stages) were distributed in the bottom far from the shore with salinity >33 psu. Surface axial distributions of younger larvae were marginally affected by the river discharge volume, tidal height and southerly wind strength. The younger and older larvae were distributed closer inshore and further offshore than the main habitat of the adults, respectively. Therefore, younger larvae were first transported inshore and moved upward to the surface layer, and then transported offshore, increasing their distribution depth. These results indicate that ark shell larvae ontogenetically change their swimming behaviour to increase their distribution depth and their axial distribution patterns may be explained by the different flow patterns among the layers of the water column in Sendai Bay. [ABSTRACT FROM AUTHOR]

Used as a traditional Chinese medicine, the high mortality rate and slow growth of Whitmania pigra larvae are the most serious bottlenecks for the scale development of artificial breeding. Firstly, five light colour treatments (white, blue, green, red and yellow) were tested to determine effects of light spectrum on the growth of larval W. pigra at the same intensity of 70.00 μmol m−2 s−1. The experiment lasted for 45 days. Under our experimental conditions, the weight gain (WG) and the specific growth rate (SGR) under blue light condition were significantly higher compared with the other treatments ( P ≤ 0.05). It is reasonable to conclude that blue light can promote the leech growth. In addition, reared at five blue light intensity treatments (20.00 ± 3.84, 40.78 ± 4.18, 53.67 ± 5.98, 70.00 ± 7.26 and 87.33 ± 5.77 μmol m−2 s−1), the WG and SGR increased with increasing intensity. Meanwhile, they were significantly higher in the 70.00 and 87.33 μmol m−2 s−1 treatments ( P ≤ 0.05). In the higher intensity light treatments, the digestive enzymes were higher and antioxidant enzymes were lower. These results suggest that the optimal light spectrum for the culture of W. pigra during the early life stage was blue and the optimal light intensity was higher light intensity (70.00-87.33 μmol m−2 s−1). [ABSTRACT FROM AUTHOR]

Light is a key environmental factor that influences the growth, culture and survival of aquatic organisms. This study examined the effects of different light qualities (red, orange, white, blue and green light) and intensities (5 μmol m−2 s−1, 15 μmol m−2 s−1 and 40 μmol m−2 s−1) on the hatching and metamorphosis of larva of Haliotis discus hannai Ino and the growth and survival of juveniles. It was found that under blue and green light, the hatching success rate and metamorphosis of larva were significantly higher than those for any other light quality ( P < 0.05), and there was a decreasing trend with an increase in light intensity. Under red and orange light, the abnormality rate of trochophores in each light intensity treatment and the time required for the metamorphosis of larva were significantly higher than those for any other light group ( P < 0.05). Both the abnormality and metamorphosis rates significantly increased with light intensity. Under white light, at an intensity of 40 μmol m−2 s−1, the settlement and size of larva at metamorphosis were significantly smaller than those for any other light intensity ( P < 0.05). Under red and orange light, the SGR of juvenile abalone in each light intensity treatment was significantly lower than that in any other light group ( P < 0.05), but no significant difference was identified ( P > 0.05). Therefore, selecting blue and green light and controlling the light intensity to 5-15 μmol m−2 s−1 during fingerling reproduction of abalone should increase the hatching success rate of larva and the yield per water body. [ABSTRACT FROM AUTHOR]

Consumption of conspecific and heterospecific eggs and larvae is common in many animal taxa, including many amphibians. Adult newts (Amphibia Urodela) often co-occur temporally and spatially with conspecific and heterospecific newt eggs and larvae, and adult individuals may benefit from their consumption, but little is known on the degree of discrimination in the newts’ predatory behaviour towards them. We performed two laboratory experiments to examine whether adult male and female alpine,Ichthyosaura alpestris(Laurenti 1768), and smooth,Lissotriton vulgaris(Linnaeus 1758), newts discriminate between conspecific and heterospecific eggs and larvae in their predatory behaviour. In our study, eight out of 64 newts succeeded in consuming eggs, although 3 times as many attacked them. We found no differences in predatory behaviour towards conspecific and heterospecific eggs, or between males and females in either species. Similarly, we found no evidence for the occurrence of discriminative predatory behaviour towards conspecific and heterospecific larvae. In our experiments the criterion for whether a newt would consume a prey item (egg or larva) was not the prey’s identity (species), but the newts’ ability to detect, capture and/or ingest it. Our results suggest that newts of both species follow an opportunistic foraging strategy, consuming whatever prey of appropriate size they manage to capture. [ABSTRACT FROM AUTHOR]

The culture of the common octopus (Octopus vulgaris) is promising since the species has a relatively short lifecycle, rapid growth, and high food conversion ratios. However, recent attempts at successful paralarvae culture have failed due to slow growth and high mortality rates. Establishing an optimal nutritional regime for the paralarvae seems to be the impeding step in successful culture methods. Gaining a thorough knowledge of food regulation and assimilation is essential for paralarvae survival and longevity under culture conditions. The aim of this study, then, was to elucidate the characteristic metabolic organization of octopus paralarvae throughout an ontogenic period of 12 days post-hatching, as well as assess the effect of diet enrichment with live prey containing abundant marine phospholipids. Our results showed that throughout the ontogenic period studied, an increase in anaerobic metabolism took place largely due to an increased dependence of paralarvae on exogenous food. Our studies showed that this activity was supported by octopine dehydrogenase activity, with a less significant contribution of lactate dehydrogenase activity. Regarding aerobic metabolism, the use of amino acids was maintained for the duration of the experiment. Our studies also showed a significant increase in the rate of oxidation of fatty acids from 6 days after-hatching. A low, although sustained, capacity for de novo synthesis of glucose from amino acids and glycerol was also observed. Regardless of the composition of the food, glycerol kinase activity significantly increased a few days prior to a massive mortality event. This could be related to a metabolic imbalance in the redox state responsible for the high mortality. Thus, glycerol kinase might be used as an effective nutritional and welfare biomarker. The studies in this report also revealed the important finding that feeding larvae with phospholipid-enriched Artemia improved animal viability and welfare, significantly increasing the rate of survival and growth of paralarvae. [ABSTRACT FROM AUTHOR]

With projected changes in the marine environment under global climate change, the effects of single stressors on corals have been relatively well studied. However, more focus should be placed on the interactive effects of multiple stressors if their impacts upon corals are to be assessed more realistically. Elevation of sea surface temperature is projected under global climate change, and future increases in precipitation extremes related to the monsoon are also expected. Thus, the lowering of salinity could become a more common phenomenon and its impact on corals could be significant as extreme precipitation usually occurs during the coral spawning season. Here, we investigated the interactive effects of temperature [24, 27 (ambient), 30, 32°C] and salinity [33 psu (ambient), 30, 26, 22, 18, 14 psu] on larval settlement, post-settlement survival and early growth of the dominant coral Platygyra acuta from Hong Kong, a marginal environment for coral growth. The results indicate that elevated temperatures (+3°C and +5°C above ambient) did not have any significant effects on larval settlement success and post-settlement survival for up to 56 days of prolonged exposure. Such thermal tolerance was markedly higher than that reported in the literature for other coral species. Moreover, there was a positive effect of these elevated temperatures in reducing the negative effects of lowered salinity (26 psu) on settlement success. The enhanced settlement success brought about by elevated temperatures, together with the high post-settlement survival recorded up to 44 and 8 days of exposure under +3°C and +5°C ambient respectively, resulted in the overall positive effects of elevated temperatures on recruitment success. These results suggest that projected elevation in temperature over the next century should not pose any major problem for the recruitment success of P. acuta. The combined effects of higher temperatures and lowered salinity (26 psu) could even be beneficial. Therefore, corals that are currently present in marginal environments like Hong Kong, as exemplified by the dominant P. acuta, are likely to persist in a warmer and intermittently less saline, future ocean. [ABSTRACT FROM AUTHOR]

The reproduction of captive Pleurodeles nebulosus was followed during five breeding seasons. The breeding season lasted from the onset of autumn to early spring. Most eggs were laid in October, although oviposition occurred throughout the breeding season. Each season a female would produce one or more clutches of 19-224 eggs. Diameter of the ova was 1.63-1.65 mm. Eggs hatched after 8-12 days, and at hatching the larvae were in Harrison stages 37-38. It took 73-108 days for the larvae to reach metamorphosis and the metamorphs measured 25.6-32.1 mm in standard length. A modest correlation was found between standard length at metamorphosis and larval development time. Juveniles, which were kept aquatic, reached maturity after 9-10 months, whereas juveniles, which were reared on land, did not reach maturity until approx. 20-22 months after metamorphosis. [ABSTRACT FROM AUTHOR]

We present here the first laboratory study on the effects of pharmacologically active compounds on the larval metamorphosis of the New Zealand geoduck, Panopea zelandica (Quoy and Gaimard, 1835). Two batches of competent hatchery-reared larvae were exposed to acetylcholine chloride, epinephrine hydrochloride and excess potassium ions in the form of KCl and K2 SO4. None of the tested chemicals increased the proportion of metamorphosed geoducks, and in some cases, the chemical caused significant mortality, despite having been used extensively with other species, such as mussels and oysters. This might indicate that geoduck larval physiology and development differs from other bivalves. Geoducks may have evolved distinct chemoreceptor patterns that facilitate metamorphosis under environmentally favourable conditions for subtidal soft sediment habitats suitable for burrowing. Thus, further research is needed to identify alternative cues (e.g. conspecific adults, sediment characteristics and surface biofilm) and understand their role in settlement and metamorphosis. This information will aid the design of reseeding methods and contribute to the development of reliable hatchery production of geoduck spat. [ABSTRACT FROM AUTHOR]

Branchiomma bairdi is a Caribbean fan worm introduced in several localities worldwide, including the Mediterranean Sea, where the species' range has rapidly expanded. Reproduction in B. bairdi was previously investigated in both extra-Mediterranean and Mediterranean areas, but no information is available on larval development and post-larval growth. In the present article, we examined these features for a population from the Mar Grande of Taranto (Ionian Sea). The species is hermaphrodite, and fertilization occurs in situ. Mucus seems to play an important role in fertilization, and also in preserving eggs before fertilization. The trochophore stage develops within the mucus and after hatching, larvae swim for about 3 d before settlement. The trochophore showed a distinct prototroch and two red dorsolateral larval eyes. The pelagic stage takes only 96 h even though prototroch is maintained after settlement, disappearing at 5 d, when larvae showed three chaetigers and branchial crown consisted of four radioles. Some interesting observations concerning changes in the morphology of chaetae and in the number of uncini during growth are also reported, together with discussion of the development of stylodes, an important diagnostic feature in Branchiomma species identification. [ABSTRACT FROM AUTHOR]

The study was aimed at to investigate the anthelmintic efficacy of aqueous and ethanolic extracts of Cucurbita pepo against gastrointestinal nematodes of sheep by scientifically validated in vitro and in vivo tests. In vitro anthelmintic activity was determined by egg hatch assay, larval migration inhibition assay and larval development assay against eggs and larvae of mixed gastrointestinal nematodes of sheep. The extracts which were found to be effective in in vitro assays were further evaluated by in vivo faecal egg count reduction test against mixed species of sheep gastrointestinal nematodes with 3 different doses (125, 250 and 500 mg kg-1). Haematological and serum parameters were estimated before and after treatment to determine the impact of plant extracts on health of the animal. Aqueous extract of C. pepo demonstrated significant inhibition of egg hatch at 40 and 80 mg/ml. The ED50 value of egg hatch inhibition was 3.51mg/ml. In larval migration inhibition assay, both aqueous and ethanolic extracts of C. pepo demonstrated inhibition of larval migration and the LM50 was 1.75 and 0.32 mg/ml respectively. However, in larval development assay, both aqueous and ethanolic extracts showed only marginal inhibition of larval development at all concentrations tested. In faecal egg count reduction test (FECRT), aqueous extracts of C. pepo at 500 mg/kg caused significant reduction in eggs per gram (96.61 per cent) the reduction being higher than the result obtained with albendazole, the positive control (93.25 per cent). There was a significant difference in EPG reduction between sheep treated with albendazole and C. pepo. Haematological and serum parameters were not affected in both the treated and untreated sheep indicating that the extracts did not cause toxic effects. Based on the results obtained in this study, the aqueous extract of C. pepo possesses anthelmintic activity and could offer an alternative source for the control of gastrointestinal nematodes of sheep. [ABSTRACT FROM AUTHOR]

Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Polydora websteribelongs to a group of the Spionidae known as thePolydoracomplex, members of which are known for building tubes within the shells of mussels and for their ability to infest commercially valuable bivalves, which causes serious losses for malacoculture.P. websteriis a species subjected to increasing research due to the global scale at which these infestations occur. In this paper, we describe the larval development ofP.cf.websteriassociated with the oysterCrassostreacf.brasilianain a tropical region of north-east Brazil. The main structures of all stages of development were analysed and compared to other populations ofP.websteri. Ovigerous capsules ofP.cf.websteriwere cultured in the laboratory and the larval stages were analysed until metamorphosis. Ovigerous capsules were present in all sampling intervals, indicating that this population exhibits continuous reproduction. Up to 21 capsules per tube were found, and the number of eggs per capsule varied from 20 to 40. All observed eggs developed into larvae. Larval development from egg to recruitment stage did not exceed 13 days. Metamorphosis occurred when larvae attained 17 chaetigers, at which stage important diagnostic characteristics were revealed, such as the spines on chaetiger 5. The developmental stages ofP.cf.websterilarvae, and the morphological features found at each stage, are in accordance with what has been recorded for temperate populations. In our study, the planktonic stage was found to be of shorter duration than elsewhere, which might be associated with the higher temperatures at which larvae were cultured compared to previous studies. [ABSTRACT FROM AUTHOR]

The distribution of the sea urchin Arbacia lixula, a warm affinity species, has been expanding in the Mediterranean Sea. To address questions on potential for future success of this species in the region, the thermotolerance of larval development was investigated in context of regional warming. The larvae were reared in present day spawning period (20 °C) and warming conditions (+4 = 24 and + 6 = 26 °C). As the calcifying larvae of sea urchins are vulnerable to stunted growth caused by ocean acidification, the impact of lower pH (--0.3 pH units) on larval development was also investigated in combination with warming. Morphological traits of the larvae, post-oral length arms, overall length of larvae and body length, were affected by increased temperature across pH treatments, indicating that for the larvae of southern Mediterranean population here, 24°C appears to approximate the optimal temperature for development. A slightly negative effect of pH was evident. Increased temperature ameliorated the stunting effect of acidification on growth. The thermal tolerance of A. lixula development overlaps with projections for warming in the region by 2100 and also indicates that this species has acclimatized or adapted its reproductive biology to the broad environmental conditions of the Mediterranean Sea. Due to the broad thermal range (~10 ° C) of development of A. lixula across its distribution, this species is likely to be a winner in the climate change stakes. The broad thermal tolerance of the larvae is likely to assure population connectivity between Mediterranean sub-basins populations. The continued success of A. lixula can have a strong consequences for the ecological structure of Mediterranean rocky habitat. [ABSTRACT FROM AUTHOR]

Background: Vector control is facing a menace due to the appearance of resistance to synthetic insecticides. Insecticides of plant origin may provide appropriate substitute biocontrol techniques in the future. The present study was carried out to investigate the bio control potentiality of active ingredient isolated from chloroform: methanol (1:1 v/v) extract of mature leaves of Solanum nigrum L. (Solanaceae) against early 3rd instar larvae of Culex vishnui group (comprising of Cx. vishnui Theobald, Cx. pseudovishnui Colless and Cx. tritaeniorhynchus Giles) and Anopheles subpictus Grassi. S. nigrum is a common plant distributed in many parts of India with medicinal properties. Methods: Bioactive compound isolated from chloroform: methanol (1:1 v/v) extract of mature leaves of S. nigrum was (25, 45, 60 mg/L) tested against early 3rd instar larvae of Cx. vishnui group and An. subpictus. The lethal concentration was determined by log probit analysis. The chemical nature of the active substance was also evaluated following gas chromatography-mass spectroscopy (GC-MS) and infrared (IR) analysis. The compound was also studied on non target organisms such as Daphnia sp. and Diplonychus annulatum. Results: TLC spot having Rf value of 0.94 (Rf = 14.1/15 = 0.94) showed larvicidal activity. In a 72 h bioassay experiment, mortality rate at 60 mg/L was significantly higher (P < 0.05) than those at 25 and 45 mg/L against early 3rd instar. Result of log-probit analysis (at 95% confidence level) revealed that LC50 and LC90 values gradually decreased with the exposure period showing the lowest value at 72 h of exposure. A clear dose-dependent mortality was observed, as the rate of mortality (Y) was positively correlated with the concentration (X) having regression coefficient value close to one in each case. The compound was found to be eco-friendly as it did not show any adverse effect to the studied non target organisms. Chemical characterization (GC-MS and IR analyses) of the active ingredient revealed the presence of phytosteroid compounds responsible for mosquito larvicidal activity. Conclusion: Leaf extract of S. nigrum has great potential as bio control agent against Cx. vishnui group and An. subpictus. In near future the isolated bioactive phytochemical could be used as a source of an effective mosquitocidal agent. [ABSTRACT FROM AUTHOR]