Larval Growth Rate Research Articles

Effectiveness Vitamin C on different Characteristics of Silkworm, Bombyx mori L.

In order to investigate effectiveness vitamin C on different characteristics of silkworm, Bombyx mori L. Silkworm larvae through 4th to 5th instar were treated with dietary supplements of ascorbic acid 7000 (VC1) and 10000 (VC2) ppm . Leaves enriched with vitamin C were fed four times per day for the larvae. Results obtained that VC1 of vitamin C is more effective than VC2 and control. It had a significant increase in biological criteria s like larval weight and larval period while economical criteria s like cocoon weight, cocoon shell weight and pupal weight. They weren’t shown any difference between VC1 and VC2 compared to control. Ascorbic acid (VC2) significantly increased the number of Prohaemocytes (Pr) 15, Granulocytes (Gr) 35.3, Plasmatocytes (Pl) 27.6 and Oenocytoides (Oe) 8 cells, respectively. This study was indicated that vitamin C has been effective on increasing the growth rate of larvae, weight of the cocoon and increasing the immunity of larvae. So, It is recommended to using it in the breeding of silkworms and production of silk commercially.

Balancing between Artemia and microdiet usage for normal skeletal development in zebrafish (Danio rerio).

Targeting in zebrafish fast growth, high survival rates and improved reproductive performance has led over the last years in variable feeding regimes between different facilities. Despite its significance on fish function and welfare, normal skeletal development has rarely been evaluated in establishing the best feeding practices for zebrafish. The aim of this study was to establish a protocol for normal skeletal development, growth and survival of zebrafish larvae through live feed-to-microdiet transition at an appropriate rate. Four feeding regimes including feeding exclusively on Artemia nauplii (A) or dry microdiet (D), and feeding on both Artemia and microdiet at two different transition rates (slow (B) or fast (C)) were applied from 5 to 24 dpf (days post-fertilization). Results demonstrated a significant effect of feeding regimes on the incidence of skeletal abnormalities (gill cover, fins and vertebral column, p<.05) in zebrafish larvae. The A and B experimental groups presented the highest (88±3 and 84±17%, respectively), but the C and D the lowest (18±14 and 11±2%, respectively), rates of normal fish (fish without any abnormality). Similarly, growth rate was comparatively elevated in A and B groups. No significant differences were observed in fish survival between A, B and C groups. However, D group presented a significantly lower survival rate. To our knowledge, this is the first study to show that the live feed-to-microdiet transition rate influences larval growth, survival and abnormality rates in a non-homogenous pattern.

Effects of fluoranthene on digestive enzymes activity and relative growth rate of larvae of lepidopteran species, Lymantria dispar L. and Euproctis chrysorrhoea L.

Fluoranthene is one of the most abundant polycyclic aromatic hydrocarbon pollutants in the environment and it may accumulate in plant leaves which are the main food source for phytophagous insect species. The aim of this study was to establish the effects of dietary fluoranthene on specific activities of digestive enzymes and expression of their isoforms in the midgut, and the relative growth rates of Lymantria dispar and Euproctis chrysorrhoea larvae. Exposure to fluoranthene led to significantly decreased trypsin activity in the midgut of larvae of both species. Leucine aminopeptidase activity decreased significantly in the midgut of L. dispar larvae exposed to the lower concentration of fluoranthene, but that enzyme activity showed the opposite trend in E. chrysorrhoea larvae. There was no pollutant induced changes in lipase activity in L. dispar, while elevated enzyme activity was recorded in the midgut of E. chrysorrhoea larvae exposed to the lower concentration of fluoranthene. Different patterns of expression of enzyme isoforms were noticed. Relative growth rates of both species significantly decreased in fluoranthene treated larvae. These responses indicate to the significance of relationships between physiological changes and fitness-related traits in L. dispar and E. chrysorrhoea larvae affected by pollutant, and contribute to understanding the mechanisms of their adjustment to stressful conditions.

Development and individual identification of captive Ziegler’s crocodile newt Tylototriton ziegleri

Tylototriton ziegleri is a newt native to Vietnam with a very limited range and assessed as Vulnerable by the IUCN. It is rarely found in captivity. Larval husbandry, based on field conditions, had mixed success with a high proportion of egg hatch and relatively rapid larval growth rates but also substantial larval mortality, probably due to high stocking density. Larvae started to hatch after 23 days and after 77-79 days had metamorphosed at a mean mass of 1.6 g; juveniles grew at an average of about 0.3 g/month. The primary animal carer was able to use wart patterns to distinguish between four individuals but scope for use on a larger scale was not supported when tested using computer-assisted individual identification software (WildID) or expert observers.

Rehabilitation of Mytilus edulis larvae abnormalities induced by K2Cr2O7 in short-term experiments.

Mytilus edulis embryo-larval development is often used as a bioassay to evaluate the negative impact of contaminants and environmental conditions. The toxicity criteria used in most protocols is the proportions of normal and abnormal larvae. The variety of abnormalities were described and classified, but further development of abnormal larvae remains obscure. This study aimed to reveal the possibility of correction of the morphological abnormalities after short-term exposure (48 h) in a variety of K2Cr2O7 concentrations. For this purpose, abnormal larvae, which developed under the negative influence of the series of K2Cr2O7 concentrations were transferred into clean seawater and studied after further 24 and 48 h. The obtained data, concerning changes in larval morphology, growth and survival rates during washing show that the abnormal larvae have enough capability to recover the normal D-shell structure. Moreover, restoration of the D-shell is possible even after exposure with concentration of the toxicant higher than the average effective one. The present research also pointed out that the development of larval shell (even abnormal one) is positively correlated with ability of the larvae to reconstruct D-shell and their survival rate. High mortality during washing occurs only at toxicant concentrations when no shell was formed within 48 h. Thus, the existence of the shell after 48 h exposure in the toxicant could indicate reversibility of the negative impact and help to distinguish the delay in development from its arrest.

The effects of adaptation to urea on feeding rates and growth in Drosophila larvae.

A collection of forty populations were used to study the phenotypic adaptation of Drosophila melanogaster larvae to urea‐laced food. A long‐term goal of this research is to map genes responsible for these phenotypes. This mapping requires large numbers of populations. Thus, we studied fifteen populations subjected to direct selection for urea tolerance and five controls. In addition, we studied another twenty populations which had not been exposed to urea but were subjected to stress or demographic selection. In this study, we describe the differentiation in these population for six phenotypes: (1) larval feeding rates, (2) larval viability in urea‐laced food, (3) larval development time in urea‐laced food, (4) adult starvation times, (5) adult desiccation times, and (6) larval growth rates. No significant differences were observed for desiccation resistance. The demographically/stress‐selected populations had longer times to starvation than urea‐selected populations. The urea‐adapted populations showed elevated survival and reduced development time in urea‐laced food relative to the control and nonadapted populations. The urea‐adapted populations also showed reduced larval feeding rates relative to controls. We show that there is a strong linear relationship between feeding rates and growth rates at the same larval ages feeding rates were measured. This suggests that feeding rates are correlated with food intake and growth. This relationship between larval feeding rates, food consumption, and efficiency has been postulated to involve important trade‐offs that govern larval evolution in stressful environments. Our results support the idea that energy allocation is a central organizing theme in adaptive evolution.

Impact of Elevated CO2 and Temperature on Growth and Development of Helicoverpa armigera Hubner

Climate change is an imminent and inevitable circumstance largely driven by increase in CO2 and temperature. CO2 directly affects plants through positive effects on net photosynthetic rate. Higher temperature during the crop growth phase can diminish the yield, with a longer growing season. In the present study, adverse climate conditions i.e. elevated CO2 (550 ppm) and elevated temperatures (29, 31, 33 and 35 ± 1 °C) were simulated in carbon dioxide and temperature gradient chambers (CTG). Growth and development of Helicoverpa armigera on non-Bt and Bt cotton leaves from those CTG chambers were recorded and correlated with foliar carbohydrates and proteins.It was found that protein content decreased by almost 42 % in non-Bt cotton and by 36 % in Bt cotton, while larval weight and duration decreased significantly with elevated conditions particularly in Bt cotton. Relative Growth Rate (RGR) increased with eCO2+ eTemp and is relatively less in non-Bt cotton compared to Bt cotton by 4-13 mg g-1 day-1. Lower protein content is positively correlated significantly to larval growth rate (r = 0.9**). Effects of climate change on crops and their pests have to be further quantified precisely to develop plausible stress mitigation strategies.

A Generalist Feeding on Brassicaceae: It Does Not Get Any Better with Selection.

Brassicaceae (Cruciferae) are ostensibly defended in part against generalist insect herbivores by toxic isothiocyanates formed when protoxic glucosinolates are hydrolysed. Based on an analysis of published host records, feeding on Brassicas is widespread by both specialist and generalists in the Lepidoptera. The polyphagous noctuid moth Helicoverpa armigera is recorded as a pest on some Brassicas and we attempted to improve performance by artificial selection to, in part, determine if this contributes to pest status. Assays on cabbage and kale versus an artificial diet showed no difference in larval growth rate, development times and pupal weights between the parental and the selected strain after 2, 21 and 29 rounds of selection, nor in behaviour assays after 50 generations. There were large differences between the two Brassicas: performance was better on kale than cabbage, although both were comparable to records for other crop hosts, on which the species is a major pest. We discuss what determines “pest” status.

Probiotic properties of an indigenous Pediococcus pentosaceus strain on Tenebrio molitor larval growth and survival

Optimising the production of insects for food and feed and ensuring their health are growing concerns for producers. Insects suffer from a range of insect pathogenic microorganisms, and the management of such diseases is essential. One solution is the introduction of beneficial probiotic bacteria into the diet of the insects. Here, we show that a lactic acid bacterial strain, Pediococcus pentosaceus, isolated from the gut of the mealworm, Tenebrio molitor, was able to inhibit the growth of selected insect pathogens in vitro. Using in vivo assessments of the host’s fitness benefits conferred by the lactic bacterium we show a significant effect of P. pentosaceus on larval growth rate and survival into adulthood. Gut microbiota analysis focusing on bacterial composition based on 16S rRNA gene amplicon sequencing suggests that P. pentosaceus could have successfully colonised the guts, or altered their bacteria, of the larvae that received it. Finally, we discuss our results in the context of mass insect production systems and outline the remaining work needed to explore and secure the role of beneficial bacterial additives in the field.

Impact of Comingled Heterospecific Assemblages on Developmentally Based Estimates of the Post-Mortem Interval-A Study with Lucilia sericata (Meigen), Phormia regina (Meigen) and Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae).

Simple SummaryIn forensic entomology, blow flies are often the first insects to arrive to decomposing remains. The development rates of blow flies are used to estimate the minimum amount of time between death and discovery of the remains, or post-mortem interval (PMI). When there are multiple species of flies interacting on the same remains, there could be changes in the development of the flies. We tested the development of three different species of blow flies in different combinations at different temperatures and measured the development and the rate of growth. One species (Lucilia sericata) grew larger when it developed with the species Phormia regina at certain temperatures. The larvae of Calliphora vicina gained weight slower when interacting with P. regina and P. regina grew faster when interacting with these two other species. Due to these differences in the development rates of the flies, depending on the species they are interacting with, more research is needed to further examine other species combinations and temperatures.Estimates of the minimum post-mortem interval (mPMI) using the development rate of blow flies (Diptera: Calliphoridae) are common in modern forensic entomology casework. These estimates are based on single species developing in the absence of heterospecific interactions. Yet, in real-world situations, it is not uncommon to have 2 or more blow fly species developing on a body. Species interactions have the potential to change the acceptance of resources as suitable for oviposition, the timing of oviposition, growth rate, size and development time of immature stages, as well as impacting the survival of immature stages to reach adult. This study measured larval development and growth rate of the blow flies Lucilia sericata (Meigen, 1826), Phormia regina (Meigen, 1826) and Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae) over five constant temperatures (15, 20, 25, 30, 35 °C), in the presence of conspecifics or two-species heterospecific assemblages. Temperature and species treatment interacted such that L. sericata larvae gained mass more rapidly when in the presence of P. regina at 20 and 30 °C, however only developed faster at first instar. At later stages, the presence of P. regina slowed development of L. sericata immatures. Development time of C. vicina immatures was not affected by the presence of P. regina, however larvae gained mass more slowly. Development time of P. regina immatures was faster in the presence of either L. sericata or C. vicina until third instar, at which point, the presence of L. sericata was neutral whereas C. vicina negatively impacted development time. Phormia regina larvae gained mass more rapidly in the presence of L. sericata at 20 °C but were negatively impacted at 25 °C by the presence of either L. sericata or C. vicina. The results of this study indicate that metrics such as development time or larval mass used for estimating mPMI with blow flies are impacted by the presence of comingled heterospecific blow fly assemblages. As the effects of heterospecific assemblages are not uniformly positive or negative between stages, temperatures or species combinations, more research into these effects is vital. Until then, caution should be used when estimating mPMI in cases with multiple blow fly species interacting on a body.

Research Article: Effeciency of Spirulina platensis cultured with different nitrogen regimes on larval development, growth and survival rate of white shrimp, Litopenaeus vannamei n.R.1

The blue-green algae Spirulina platensis was cultured with different nitrogen regimes (NH4Cl, NH4NO3 and KNO3) with concentrations of 0.010, 0.025 and 0.050 M and then fed to Litopenaeus vannamei at 19 days post hatch (PLI) to evaluate the nutritional quality. At the end of the experiment, growth and survival rate were determined, and the larval development was calculated. The maximum protein content was obtained in culture media containing NH4NO3 followed by NH4Cl and KNO3 (p >0.05). Moreover, in all S. platensis cultures, increases in nitrogen concentrations led to increases in protein content. The present study showed that, with the exception of shrimp larvae at 5 days post hatch, L. vannamei shrimp larvae fed on S. platensis cultured in NH4NO3, as a nitrogen regime, generally developed significantly (p 0.05) when the nitrogen was varied in terms of regimes. Overall, the study points to the potential effectiveness of using NH4NO3 as a nitrogen regime in S. platensis culture media in producing live food for the hatchery production of L. vannamei shrimp larvae.

Chemical safety of black soldier fly larvae (Hermetia illucens), knowledge gaps and recommendations for future research: a critical review

Black soldier fly larvae (Hermetia illucens) (BSFL) are a promising protein source for the feed industry. They can be used to convert organic waste into valuable biomass, and due to their chemical composition, they are a valuable ingredient for several industrial sectors. To use BSFL as a feed ingredient, their chemical safety must be guaranteed. The composition of their rearing substrate is one of the crucial factors for safety, since it might introduce safety risks by bioaccumulation of various (in)organic compounds (e.g. toxic metals, mycotoxins, pesticides, etc.) in BSFL. Though several organic waste streams are potential and valuable rearing substrates for BSFL, the European Union currently does not allow their use due to safety knowledge gaps. This has prompted researchers to conduct several exposure experiments by artificially spiking chemicals to the rearing substrate of BSFL to investigate such risks. Here, we present a critical overview of the current body of literature on this topic and discuss the main findings, gaps, and recommendations for future research. Overall, BSFL do not seem to accumulate contaminants above the European feed legislation limits, except for certain metals (i.e. cadmium, lead, and zinc), which can jeopardise the chemical safety of the BSFL. For all compounds explored to date, except for cyromazine and pyriproxyfen, their presence in the substrate has no effect on the larval growth or survival rate. However, the remaining knowledge gaps concerning other potential hazardous chemicals (e.g. plasticisers, flame retardants, etc.) and their degradation pathways in BSFL still warrant an appropriate chemical safety assessment and can be a reason why several organic waste streams are not yet allowed to grow BSFL. The risks induced by the potential presence and accumulation of other chemical compounds requires further research to enable the safe exploitation of BSFL.

Microclimatic variability buffers butterfly populations against increased mortality caused by phenological asynchrony between larvae and their host plants

Climate change affects insects in several ways, including phenological shifts that may cause asynchrony between herbivore insects and their host plants. Insect larvae typically have limited movement capacity and are consequently dependent on the microhabitat conditions of their immediate surroundings. Based on intensive field monitoring over two springs and on larger‐scale metapopulation‐level survey over the same years, we used Bayesian spatial regression modelling to study the effects of weather and microclimatic field conditions on the development and survival of post‐diapause larvae of the Glanville fritillary butterflyMelitaea cinxiaon its northern range edge. Moreover, we assessed whether the observed variation in growth and survival in a spring characterized by exceptionally warm weather early in the season translated into population dynamic effects on the metapopulation scale. While similar weather conditions enhanced larval survival and growth rate in the spring, microclimatic conditions affected survival and growth contrastingly due to the phenological asynchrony between larvae and their host plants in microclimates that supported fastest growth. In the warmest microclimates, larvae reached temperatures over 20°C above ambient leading to increased feeding, which was not supported by the more slowly growing host plants. At the metapopulation level, population growth rate was highest in local populations with heterogeneous microhabitats. We demonstrate how exceptionally warm weather early in the spring caused a phenological asynchrony between butterfly larvae and their host plants. Choice of warmest microhabitats for oviposition is adaptive under predominant conditions, but it may become maladaptive if early spring temperatures rise. Such conditions may lead to larvae breaking diapause earlier without equally advancing host plant growth. Microclimatic variability within and among populations is likely to have a crucial buffering effect against climate change in many insects.

Temperature reduces fish dispersal as larvae grow faster to their settlement size.

As species struggle to cope with rising ocean temperatures, temperate marine assemblages are facing major reorganization. Many benthic species have a brief but critical period dispersing through the plankton, when they are particularly susceptible to variations in temperature. Impacts of rising temperatures can thus ripple through the population with community-wide consequences. However, responses are highly species-specific, making it difficult to discern assemblage-wide patterns in the life histories of different fish species. Here, we evaluate the responses to temperature in the early life histories of several fish species using otolith reconstructive techniques. We also assess the consequences of future warming scenarios to this assemblage. We sampled recent settlers of nine common species across a temperature gradient in the Mediterranean Sea and obtained environmental data for each individual. Using otolith microstructure, we measured early life traits including pelagic larval duration (PLD), growth rate, settlement size, hatching and settlement dates. We used a GLM framework to examine how environmental variables influenced early life-history parameters. We show that increasing temperature results in considerable reduction in the dispersal potential of temperate fish. We find a nearly universal, assemblage-wide decline in pelagic larval duration (PLD) of between 10% and 25%. This was because, with increasing temperature, larvae grew quicker to their settlement size. Settlement size itself was less affected by temperature and appears to be an ontogenetically fixed process. Given current estimates of ocean warming, there could be an assemblage-wide reduction in larval dispersal of up to 50km across the Mediterranean, reducing connectivity and potentially isolating populations as waters warm.

Fijian swallowtail butterfly Papilio schmeltzi (Papilionidae: Lepidoptera) shows clear preference–performance relationships on both native and exotic host plants

AbstractThe swallowtail butterfly Papilio schmeltzi is endemic to the Fiji Islands. To date, P. schmeltzi larvae and eggs have been found exclusively on a native Fijian shrub, Micromelum minutum, even though numerous other seemingly suitable native and exotic species of Rutaceae now occur in its Fijian forest habitat. This study used outdoor cages and laboratory studies to examine oviposition preferences and larval development of P. schmeltzi on four species of Rutaceae: the native species Micromelum minutum and Euodia hortensis and the introduced species Murraya koenigii and Citrus reticulata. The female oviposition preference sequence was the same as that for larval feeding preference, which ran, from most preferred, as Micromelum minutum &gt; C. reticulata &gt; Murraya koenigii &gt; E. hortensis. The survival of the first and fifth instar larvae was highest (≥80%) when maintained on leaves of M. minutum and C. reticulata and lowest when reared on Murraya koenigii (≤20%) and E. hortensis (≤4%). Of the two preferred host plants, P. schmeltzi larvae gained weight more quickly, consumed a larger area of leaf and pupated earlier when reared on the natural host Micromelum minutum compared with the exotic C. reticulata. In quantitative nutritional studies, the consumption rate of leaf material, and the relative growth rate of the P. schmeltzi larvae, was highest when reared on Micromelum minutum compared with C. reticulata, although the efficiency of converting leaf biomass into larval biomass was highest when reared on C. reticulata, especially in the later instars. Overall, the results of our study indicate the plants on which P. schmeltzi females choose to lay eggs are not restricted to native Fijian plant species but are appropriate when viewed in terms of subsequent larval preferences, survival and growth rate.

Linking variability in early life growth of Sardinella lemuru to changes in habitat conditions in Zamboanga upwelling system, Sulu Sea, the Philippines

The year-class success of small pelagic fish is strongly modulated by the growth and survival of early life stages. Determining how environments control growth is critical to understanding processes influencing annual production. We provide the first measurements of larval growth in Sardinella lemuru, the most abundant and exploited tropical sardine species in the Philippines. Growth rates of larvae were examined across a 2 yr period (2011-2012 and 2012-2013 spawning seasons) using otolith microstructure analysis. Transition to the juvenile stage occurred within 25 to 37 d. Mean growth rate of the 2011 year-class was significantly lower than the 2012 year-class despite significant intra-annual (batch) differences in growth trajectories. In both years, larvae that hatched and developed in the cooler yet prey-rich period in the middle of the spawning season (January) displayed the fastest growth, while those spawned early (September-October 2012) and late (February-March 2012) showed the slowest growth rates. Peak hatch-months (December 2011 and October 2012) were just prior to periods of upwelling, with mean prey concentrations of 0.24 ± 0.13 mg m-3 at 26.35 ± 2.56°C sea surface temperature (SST) and 0.23 ± 0.15 mg m-3 at 26.26 ± 1.79°C, respectively. The SST during upwelling was 0.01 to 1.23°C cooler accompanied by a 0.07 to 0.45 mg m-3 increase in prey concentration. In both years, differences in growth rate were strongly linked to oceanographic conditions. Moderate winds during a ‘neutral’ El Niño-Southern Oscillation year resulted in upwelling conditions favoring faster overall growth in larvae which was associated with stronger recruitment. In contrast, slower growth and weaker recruitment were associated with weak upwelling conditions in the 2011-2012 La Niña year. While temperature may be important, larval growth rates appear to be driven more by prey abundance.

Spawning sources of a coastal fishery species inferred from otolith chemistry and microstructure: implications for management

Spawning sources of King George whiting Sillaginodes punctatus populations in the states of South Australia and Victoria (south-eastern Australia) were analysed using otolith chemistry and microstructure from post-larvae sampled from 3 nursery areas in each state in the spring of 2011 and 2012. Univariate and multivariate analysis of the chemistry of the core region of otoliths showed differences between states, particularly for the 2011 cohort, primarily related to higher Mg in South Australian samples, while differences in Sr and Zn also made a contribution. Even though spawning times overlapped, early larval growth rates were higher for post-larvae from South Australia than Victoria. Differences in microchemistry were most evident for elements influenced by physiological processes and were potentially influenced by the different larval growth rates. Overall, otolith chemical and microstructure analyses for post-larvae in Victoria and South Australia indicated that spawning sources for the 2 states were different, qualified by results from otolith microchemistry that were less clear for the 2012 cohort. Even though genetic analyses do not indicate genetic differentiation across the 2 states, and therefore would support cross-jurisdictional management, the results of this study give qualified support to the current arrangement wherein the S. punctatus fishery is managed separately by the individual jurisdictions, subject to further information on stock structure coming to light in the future.

Simulating fish population responses to elevated CO2: a case study using winter flounder

Scaling experimentally derived effects of CO2 on marine fauna to population responses is critical for informing management about potential ecological ramifications of ocean acidification. We used an individual-based model of winter flounder to extrapolate laboratory-derived effects of elevated CO2 assumed for early life stages of fish to long-term population dynamics. An offspring module with detailed hourly to daily representations of spawning, growth, and mortality that incorporates potential elevated CO2 effects was linked to an annual time-step parent module. We calibrated the model using a 40 yr Reference simulation (1977-2016) that included gradual warming and then performed ‘Retrospective’ simulations that assumed a suite of elevated CO2 effects by changing fertilization rate, mortality rate of embryos due to developmental malformations, larval growth rate, and size-at-settlement. ‘Recovery’ simulations that started at low population size were then used to further explore possible interactions between the effects of CO2 and warming on population productivity. Warming had a major negative effect on the simulated winter flounder population abundance, and reduced larval growth had the largest single impact among the CO2 effects tested. When a combination of the assumed CO2 effects was imposed together, average annual recruitment and spawning stock biomass were reduced by half. In the Recovery simulations, inclusion of CO2 effects amplified the progressive decrease in population productivity with warming. Our analysis is speculative and a first step towards addressing the need for extrapolating from laboratory effects of ocean acidification to broader, ecologically relevant scales.

Short term temperature fluctuations affect embryonic and larval development of yellow perch (Perca flavescens)

Early life stages of fishes are critical stages due to their importance in enhancing recruitment. Given the high mortality through the embryonic and larval stages, managers have started investigating factors that impact these stages. Environmental factors, such as water temperature, have been found to play a larger role in early life survival. Climate change predications will be more apparent in northern temperate systems like the Great Lakes. Yellow perch Perca flavescens are an important sport fish in the region whose populations have been declining since the 1980s. Yellow perch recruitment is highly erratic due to the species dependence on spring water temperatures. With warming waters occurring earlier in the seasons, it is unsure how wild yellow perch will adapt. The objective of this study was to determine how variations in temperature regimes during the egg incubation period would impact embryonic and larval development in yellow perch. Four different temperature treatments were used in this study: steady temperature at 16°C, a gradient starting at 12°C increasing by 1-2°C every 3-4 days, a heat shock on day six of 20°C for 16 hours to mimic a heat wave event, and finally, a cold shock on day six of 10°C temperatures for 16 hours to mimic a cold snap event. The results of this study confirm that water temperatures severely impact embryonic development and incubation periods of yellow perch, having a significant impact on the percent of failed larvae at the end of the incubation period (P= 0.0005), with the cold shock affecting the lowest percent of failed larvae (0.8%) while the steady treatment had the highest percent (22.9%). Temperature treatment did have a significant impact on the time it took for larvae to successfully hatch out (P&lt;0.001), but no significant effect on observed mortality and estimated mortality (P= 0.96), percent of surviving larvae (P=0.35), or average growth rate of larvae (P=0.16).This study reveals that yellow perch are better adapted to withstand acute cold shifts in water temperature than acute warming events. Climate change could potentially hinder an already struggling Lake Michigan yellow perch population.

Coordinated control of adiposity and growth by anti-anabolic kinase ERK7.

Energy storage and growth are coordinated in response to nutrient status of animals. How nutrient‐regulated signaling pathways control these processes in vivo remains insufficiently understood. Here, we establish an atypical MAP kinase, ERK7, as an inhibitor of adiposity and growth in Drosophila. ERK7 mutant larvae display elevated triacylglycerol (TAG) stores and accelerated growth rate, while overexpressed ERK7 is sufficient to inhibit lipid storage and growth. ERK7 expression is elevated upon fasting and ERK7 mutant larvae display impaired survival during nutrient deprivation. ERK7 acts in the fat body, the insect counterpart of liver and adipose tissue, where it controls the subcellular localization of chromatin‐binding protein PWP1, a growth‐promoting downstream effector of mTOR. PWP1 maintains the expression of sugarbabe, encoding a lipogenic Gli‐similar family transcription factor. Both PWP1 and Sugarbabe are necessary for the increased growth and adiposity phenotypes of ERK7 loss‐of‐function animals. In conclusion, ERK7 is an anti‐anabolic kinase that inhibits lipid storage and growth while promoting survival on fasting conditions.