Larval Period Research Articles

Functional Study of the Role of the Methyl Farnesoate Epoxidase Gene in the Ovarian Development of Macrobrachium nipponense.

Methyl farnesoate epoxidase (MFE) is a gene encoding an enzyme related to the last step of juvenile hormone biosynthesis. Mn-MFE cDNA has a total length of 1695 bp and an open reading frame (ORF) length of 1482 bp, encoding 493 amino acids. Sequence analysis showed that its amino acid sequence has a PPGP hinge, an FGCG structural domain, and other structural domains specific to the P450 family of enzymes. Mn-MFE was most highly expressed in the hepatopancreas, followed by the ovary and gill, weakly expressed in heart and muscle tissue, and barely expressed in the eyestalk and cranial ganglion. Mn-MFE expression remained stable during the larval period, during which it mainly played a critical role in gonadal differentiation. Expression in the ovary was positively correlated and expression in the hepatopancreas was negatively correlated with ovarian development. In situ hybridization (ISH) showed that the signal was expressed in the oocyte, nucleus, cell membrane and follicular cells, and the intensity of expression was strongest at stage O-IV. The knockdown of Mn-MFE resulted in a significantly lower gonadosomatic index and percentage of ovaries past stage O-III compared to the control group. However, no differences were found in the cumulative frequency of molting between the experimental and control groups. Moreover, the analysis of ovarian tissue sections at the end of the experiment showed differences between groups in development speed but not in subcellular structure. These results demonstrate that Mn-MFE promotes the ovarian development of Macrobrachium nipponense adults but has no effect on molting.

Effects of industrial pollution and ambient air temperature on larval performance and population dynamics of Eriocrania leafminers (Lepidoptera)

Pollution is an integral part of global environmental change, yet the combined and interactive effects of pollution and climate on terrestrial ecosystems remain inadequately understood. This study aims to explore whether pollution alters the impacts of ambient air temperature on the population dynamics of herbivorous insects. Between 1995 and 2005, we studied populations of two closely related moths, Eriocrania semipurpurella and E. sangii, at eight sites located 1 to 64 km from a large copper‑nickel smelter in Monchegorsk, Russia. We found that pollution and temperature influence the performance of Eriocrania larvae mining in the leaves of mountain birch, Betula pubescens var. pumila, through multiple pathways. This is evident from the unconsistent changes observed in larval and frass weight, mine area, and leaf size. We found increases in both leaf quality and larval weight with decreasing pollution levels at both spatial and temporal scales and attributed these to the impact of sulphur dioxide, rather than trace elements (nickel and copper). The quality of birch leaves increased with spring (May) temperatures, enabling Eriocrania larvae to achieve greater weight while consuming less biomass. During the larval growth period (early June to early July), Eriocrania larvae increased their consumption with rising temperatures, presumably to compensate for increased metabolic expenses. Contrary to our expectations, the per capita rate of population change did not correlate with larval weight and did not vary along the pollution gradient. Nevertheless, we detected interactive effects of pollution and climate on the rate of population change. This rate decreased with rising winter temperatures in slightly polluted and unpolluted sites but remained unchanged in heavily polluted sites. We conclude that pollution disrupts mechanisms regulating the natural population dynamics of Eriocrania moths.

Biology and Morphometrics of Fall armyworm (Spodoptera frugiperda) in Chitwan, Nepal

The Fall armyworm (FAW) Spodoptera frugiperda, native to the Americas, is an important invasive and polyphagous pest threatening cereal production. Abiotic and biotic factors, including climatic uncertainty and insect pests like S. frugiperda, pose threats. Detected in East Africa in 2016 and reported in Nawalpur, Nepal, on May 9, 2019, FAW has led to a 34% decline in maize yields. Studying FAW's biology and morphometrics is crucial for understanding its habitat and ecology, essential prerequisites for adopting integrated management strategies. Biological parameters such as incubation period, larval and pupal duration, pre-oviposition and, oviposition periods, male and female adult longevity, larval and pupal mortality, sex ratio (male: female), and morphometrics of egg, larvae, pupa, and adult were measured. The incubation period (2-3 days), larval and pupal periods (13-18 and 9-12 days) with overall life duration (31-45 days) were recorded in maize. Head capsule width of the first, second, third, fourth, fifth, and sixth instar were recorded as 0.52±0.05, 0.73±0.05, 1.1±0.05, 1.74±0.12, 2.04±0.15, and 2.91±0.23 mm respectively. Mean body length of different larval instars were recorded as 3.33±0.26, 6.92±1.07, 13.11±1.45, 16.82±1.57, 28.68±1.75, and 34.56±1.99 mm for the first, second, third, fourth, fifth, and sixth instar respectively.

The Evaluation of Toxicity Effects of Synthetic Volatile Compounds and Essential Oils on Callosbruchus maculatus L. and its Biology

The biology studies and contact toxicity of synthetic volatile compounds, namely Propionic acid and Benzaldehyde, and essential oils namely, Ocimum basilicum and Mentha piperita, and their different possible combinations evaluated against Callosobruchus maculatus and were carried out at the Department of Entomology, Annamalai University to develop an economically viable and effective alternative to chemical insecticides to manage the stored product insect pests. In the biology study, the egg period was 5±0.07 days. The larval and pupal period together was 21.24±0.67. The total development period recorded from the day of oviposition to adult emergence was 35.03±0.35 days. The maximum contact toxicity was observed in Propionic acid + Benzaldehyde with 8.73 µl LC50. Therefore, in addition to being incorporated into the storage pest management to prevent the development of resistance, combinations of essential oils and synthetic volatiles, such as propionic acid and benzaldehyde, could be used as an alternative to the chemical fumigants that are mostly used to control pests of stored products.

ANTIBIOSIS AND ANTIXENOSIS IN TOMATO GENOTYPES AGAINST Helicoverpa armigera HUBNER

<p><strong>Background</strong>. Farmers rely on the use of synthetic insecticides in managing <em>Helicoverpa</em> <em>armigera</em>, hole-boring insect pest on tomato, but they are detrimental to human health. Therefore a more reliable and ecofriendly control measure is needed such as host plant resistance<strong>. Objective</strong>. To assess the mechanisms of resistance in tomato varieties: NGB00724, NGB00724, Anaya, Kelvin, Mona, Roma VF (susceptible varieties), Tropimech and UC82B in laboratory and screen house. <strong>Methodology</strong>. Second larval instars were fed with leaves of the different tomato varieties and their development was observed till adult stage. Study was done in the screen house where number of larvae and eggs were also observed. Larval period and weight, and percentage adult emergence were assessed in tomato varieties. Metabolites (phenol, flavonoids, terpenoids, protein, reducing sugars and total sugars) in tomato leaves were determined following standard procedures. <strong>Results</strong>. <em>Helicoverpa</em> <em>armigera</em> fed with tomato leaves, Anaya recorded the lowest larval period (9.67 days). Also, larvae fed on Anaya and Mona had the lowest larval weight (0.19 g and 0.25 g). Also significantly lower percentage of adult emergence was observed on Anaya and Mona (16.7%) Mona, NGB00725 and Anaya significantly harbored the lower number of <em>Helicoverpa</em> <em>armigera</em> adult (0.1, 0.4, 0.4). The lowest number of eggs (0.5) was recorded from adults placed on Anaya variety. There was high and negative significant correlation of r = -0.865 between phenols and adult emergence. Phenols and oviposition were significantly negatively correlated (r = -0.816). <strong>Implication. </strong>Anaya and Mona hinder the development of <em>Helicoverpa</em> <em>armigera</em> larvae when fed on it. Phenol has negative impact on the development and oviposition of <em>Helicoverpa</em> <em>armigera</em>. <strong>Conclusion</strong>. It was revealed through this study that availability of promising resistant varieties can effectively combat the damage caused by <em>Helicoverpa</em> <em>armigera</em> and lessen the shortcomings related with the application of conventional chemical insecticides in tomato production.</p>

Transcriptome analysis of the Japanese eel (Anguilla japonica) during larval metamorphosis

BackgroundAnguillid eels spend their larval period as leptocephalus larvae that have a unique and specialized body form with leaf-like and transparent features, and they undergo drastic metamorphosis to juvenile glass eels. Less is known about the transition of leptocephali to the glass eel stage, because it is difficult to catch the metamorphosing larvae in the open ocean. However, recent advances in rearing techniques for the Japanese eel have made it possible to study the larval metamorphosis of anguillid eels. In the present study, we investigated the dynamics of gene expression during the metamorphosis of Japanese eel leptocephali using RNA sequencing.ResultsDuring metamorphosis, Japanese eels were classified into 7 developmental stages according to their morphological characteristics, and RNA sequencing was used to collect gene expression data from each stage. A total of 354.8 million clean reads were generated from the body and 365.5 million from the head, after the processing of raw reads. For filtering of genes that characterize developmental stages, a classification model created by a Random Forest algorithm was built. Using the importance of explanatory variables feature obtained from the created model, we identified 46 genes selected in the body and 169 genes selected in the head that were defined as the “most characteristic genes” during eel metamorphosis. Next, network analysis and subsequently gene clustering were conducted using the most characteristic genes and their correlated genes, and then 6 clusters in the body and 5 clusters in the head were constructed. Then, the characteristics of the clusters were revealed by Gene Ontology (GO) enrichment analysis. The expression patterns and GO terms of each stage were consistent with previous observations and experiments during the larval metamorphosis of the Japanese eel.ConclusionGenome and transcriptome resources have been generated for metamorphosing Japanese eels. Genes that characterized metamorphosis of the Japanese eel were identified through statistical modeling by a Random Forest algorithm. The functions of these genes were consistent with previous observations and experiments during the metamorphosis of anguillid eels.

Incidence of Rice Stem Borers in Coastal Andhra Pradesh with Emphasis on <i>Sesamia inferens</i> (Walker)

A roving survey was conducted in the rice crop grown in coastal districts of Andhra Pradesh during rabi, 2021-22 and 2022-23. Overall mean stem borer incidence varied from 13.59% - 14.83% in both the seasons. Larvae of Scirpophaga incertulas (Walker), Sesamia inferens (Walker), Chilo polychrysus (Meyers) and Chilo auricilius (Dudgeon), were recorded from four districts during the survey. Among the stem borers, S. incertulas was the most predominant species (53.37%) followed by S. inferens (44.7%). Natural larval parasitization (21%) of S. inferens by Cotesia flavipes Cameron was observed in West Godavari district. The biology of S. inferens was studied on rice cv. MTU 1121. The average larval period recorded was 32.40± 0.35 days. Total life cycle of S. inferens ranged between 41-65 and 46-73 days for male and female moths, respectively. Current study suggests that S. inferens could be a potential threat to rice cultivation in coastal Andhra Pradesh.

A genome-wide association study and an accurate genotyping strategy to identify and validate the SNPs related to the larval period in bullfrog Aquarana catesbeiana

A genome-wide association study and an accurate genotyping strategy to identify and validate the SNPs related to the larval period in bullfrog Aquarana catesbeiana

Effects of warming at embryonic and larval stages on tadpole fitness in high-altitude Rana kukunoris

Global warming may affect the early developmental stages of high-altitude amphibians, thereby influencing their later fitness. Yet, this has been largely unexplored. To investigate whether and how the temperatures experienced by embryonic and larval stages affect their fitness at later developmental stages, we designed two experiments in which the embryos and larvae were treated with three temperatures (24, 18 and 12 °C), respectively. Then, the life history traits of the tadpoles during the metamorphotic climax in all treatments were evaluated, including growth rate, survival rate, morphology, thermal physiology, swimming performance, standard metabolic rate (SMR), oxidative and antioxidative system, and metabolic enzyme activities. The results revealed that elevated temperature accelerated metamorphosis but decreased body size at metamorphosis. Additionally, warming during the embryonic and larval stages decreased the thermal tolerance range and induced increased oxidative stress. Furthermore, high embryonic temperature significantly decreased the hatching success, but had no significant effect on swimming performance and SMR. Warming during larval periods was harmful to the survival and swimming performance of tadpoles. The effect size analysis revealed that the negative impacts of embryonic temperature on certain physiological traits, such as growth and development, survival and swimming performance, were more pronounced than those of larval temperature. Our results highlight the necessity for particular attention to be paid to the early stages of amphibians, notably the embryonic stages when evaluating the impact of global warming on their survival.

Biology of Sitophilus oryzae (Coleoptera) on stored Wheat Genotypes

The biology of five different genotypes of rice weevil in stored wheat was studied in the laboratory of PG Department of Botany, Jai Prakash University Chapra (Bihar). The study found that the different developmental stages of the rice weevil were longer in winter than in summer. HUW 214 recorded the lowest incubation period of 7.53 days, while HI 8498 recorded the longest incubation period of 9.68 days. HUW 214 had the lowest total larval period (23.27 days), while HI 8598 had the highest larval period (32.38 days). The total growth period was lowest in HUW 214(41.81 days) and highest in HI 8498(56.04 days).

Impact of different host plants on biology and morphometrics of various developmental stages of Papilio demoleus (Linn.)

The comparative studies under laboratory conditions have been carried out to investigate the influence of different alternative host plants viz., bael [Aegle marmelos (L.)], curry leaves [Murraya koenigii (L.) Spreng.], ber (Zizyphus mauritiana Lam.) and lemon [Citrus limon (L.) Burm.f.] on biology and morphometrics of Lemon butterfly, Papilio demoleus (Linn.). The lemon is the most preferred host of P. demoleus used as a controlled experimental host plant. The variations in periods of larval, pupal and rate of emergence into adult have been recorded and found that the lemon was the most preferred host plant on which all the larval stages survived smoothly. The caterpillars when reared on alternative hosts showed an increase in average larval period. The average survival percent of larvae were reported highest on bael leaves, followed by curry leaves and ber leaves. Similar patterns of results were also recorded on the pupal period and rate of emergence with alternative hosts. The morphometric variations in weight, size and colour of caterpillars, pupae and adults were also measured and found in decreasing order of host preferences as lemon[greater than]bael[greater than]curry[greater than]ber.

N(alpha)-acetyltransferase 40-mediated histone acetylation plays an important role in ecdysone regulation of metamorphosis in the red flour beetle, Tribolium castaneum

Histone acetylation, a crucial epigenetic modification, is governed by histone acetyltransferases (HATs), that regulate many biological processes. Functions of HATs in insects are not well understood. We identified 27 HATs and determined their functions using RNA interference (RNAi) in the model insect, Tribolium castaneum. Among HATs studied, N-alpha-acetyltransferase 40 (NAA40) knockdown caused a severe phenotype of arrested larval development. The steroid hormone, ecdysone induced NAA40 expression through its receptor, EcR (ecdysone receptor). Interestingly, ecdysone-induced NAA40 regulates EcR expression. NAA40 acetylates histone H4 protein, associated with the promoters of ecdysone response genes: EcR, E74, E75, and HR3, and causes an increase in their expression. In the absence of ecdysone and NAA40, histone H4 methylation by arginine methyltransferase 1 (ART1) suppressed the above genes. However, elevated ecdysone levels at the end of the larval period induced NAA40, promoting histone H4 acetylation and increasing the expression of ecdysone response genes. NAA40 is also required for EcR, and steroid-receptor co-activator (SRC) mediated induction of E74, E75, and HR3. These findings highlight the key role of ecdysone-induced NAA40-mediated histone acetylation in the regulation of metamorphosis.

The role of phenotypic plasticity and corticosterone in coping with pond drying conditions in yellow-bellied toad (Bombina variegata, Linnaeus 1758) tadpoles.

Amphibian larvae inhabiting temporary ponds often exhibit the capacity to accelerate development and undergo metamorphosis in challenging conditions like desiccation. However, not all species exhibit this ability, the yellow-bellied toad (Bombina variegata) is one such example. The underlying mechanisms behind the inability to accelerate development under desiccation remain largely unexplored. The hypothalamic-pituitary-interrenal (HPI) axis and corticosterone (CORT), which act synergistically with thyroid hormone, are thought to facilitate metamorphosis in response to desiccation stress. In this study, we aimed to investigate whether modification in the HPI axis, particularly CORT levels, contributes to the absence of adaptive plasticity in B. variegata under desiccation stress. The study design included four treatments: high water level, high water level with exogenous CORT, low water level, and low water level with metyrapone (a CORT synthesis inhibitor). The main objective was to evaluate the effects of these treatments on whole-body corticosterone levels, life history, morphological traits, and oxidative stress parameters during the prometamorphic and metamorphic climax developmental stages. While low water level had no effect on total corticosterone levels, larval period, body condition index, and metamorphic body shape, it negatively affected metamorph size, mass, and growth rate. Our findings suggest that constant exposure to desiccation stress over generations may have led to modifications in the HPI axis activity in B. variegata, resulting in adaptation to changes in water level, evident through the absence of stress response. Consequently, CORT may not be a relevant stress indicator in desiccation conditions for this species.

Exposure to entomopathogenic fungus and high larval density induce a strong immune response and life‐history costs in black soldier fly, a commercially important insect

AbstractPathogen infection and conspecific density may considerably affect key life‐history traits of organisms. For naturally aggregating species, even low concentrations of pathogens or high larval densities may have detrimental effects. However, the detailed influence of these factors, particularly their interaction effect, is often overlooked in ecological and life‐history studies. To investigate the effects of conspecific density and pathogen infection on life‐history traits, we explored the influence of larval density (1 and 5 larvae cm−2, i.e., low and high density, respectively) on phenoloxidase (PO) activity, body mass, and development time of Hermetia illucens L. (Diptera: Stratiomyidae) larvae in the presence of two strains of the entomopathogenic fungus (EPF) Beauveria bassiana (Bals.‐Criv.) Vuill. We observed higher PO activity in EPF‐treated larvae than in the untreated control and a pronounced difference in PO activity between the two EPF‐strain treatments. Larvae reared at high density and treated with EPF showed higher PO activity than untreated larvae at low density. The EPF‐treated larvae and larvae reared at high density had longer larval periods than untreated larvae and larvae reared at low density, respectively. Larvae reared at high density also achieved reduced prepupal and pupal masses compared to conspecifics at low density. Interestingly, untreated larvae only achieved higher prepupal and pupal masses at low density, whereas at high density, the pattern was reversed (treated individuals had higher pupal masses). Overall, our results demonstrate that high density and fungal pathogens both induce a higher immune response compared to low density and pathogen‐free environments, but this comes with a cost of a longer larval period and reduced body mass.

Effect of Temperature and Humidity on the Biology and Morphometric Measurement of Groundnut Bruchid (Caryedon serratus Olivier) [Coleoptera: Bruchidae] in Groundnut Seed

The experiment determined the effects of varying temperatures and relative humidity on the biology and morphometrics of Caryedon serratus. The temperatures were 30, 35, and 40⁰C and relative humidity differences were 60, 65, and 70%. The results show that eggs hatched in 3-4 days at 30⁰C and 60% RH, 4-5 days at 35⁰C and 65% RH, 6-7 days at 40⁰C and 70% RH respectively. Larval period ranges from 19-23 days at 30 ̊C and 60% RH, 14-18 days at 35 ̊C and 65% RH, 14-18 days at 40 ̊C and 70% RH respectively. The morphometric measurements showed that the average length and breadth of eggs were 0.58 mm and 0.15 mm. The mean length and breadth of larval stages were 0.69, 1.27, 2.52, 3.58 mm and 0.35, 0.86, 1.35, and 2.10 mm respectively. The average length and breadth of the pupa were 4.60 mm and 3.00 mm. The mean length and breadth of adults were 4.10 mm and 3.40 mm. The life cycle of bruchid took 33-40, 14-18, and 16-20 days to complete at temperature degrees of 30, 35, 40⁰C and relative humidity ranges of 60, 65, and 70%. Therefore, this work has recommended that the standard optimum temperature and humidity for the best performance of C. serratus particularly on stored groundnut seeds ranges between 30-35⁰C and 60-65% RH. Farmers and all those involved in the storage of groundnut are admonished to be cautious of this period.

Exposure to Bisphenol F and Bisphenol S during development induces autism-like endophenotypes in adult Drosophila melanogaster

Bisphenol F (BPF) and Bisphenol S (BPS) are being widely used by the industry with the claim of “safer substances”, even with the scarcity of toxicological studies. Given the etiological gap of autism spectrum disorder (ASD), the environment may be a causal factor, so we investigated whether exposure to BPF and BPS during the developmental period can induce ASD-like modeling in adult flies. Drosophila melanogaster flies were exposed during development (embryonic and larval period) to concentrations of 0.25, 0.5, and 1 mM of BPF and BPS, separately inserted into the food. When they transformed into pupae were transferred to a standard diet, ensuring that the flies (adult stage) did not have contact with bisphenols. Thus, after hatching, consolidated behavioral tests were carried out for studies with ASD-type models in flies. It was observed that 1 mM BPF and BPS caused hyperactivity (evidenced by open-field test, negative geotaxis, increased aggressiveness and reproduction of repetitive behaviors). The flies belonging to the 1 mM groups of BPF and BPS also showed reduced cognitive capacity, elucidated by the learning behavior through aversive stimulus. Within the population dynamics that flies exposed to 1 mM BPF and 0.5 and 1 mM BPS showed a change in social interaction, remaining more distant from each other. Exposure to 1 mM BPF, 0.5 and 1 mM BPS increased brain size and reduced Shank immunoreactivity of adult flies. These findings complement each other and show that exposure to BPF and BPS during the development period can elucidate a model with endophenotypes similar to ASD in adult flies. Furthermore, when analyzing comparatively, BPS demonstrated a greater potential for damage when compared to BPF. Therefore, in general these data sets contradict the idea that these substances can be used freely.

Biology and host preference studies of Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) in Ethiopia

The fall armyworm (FAW), Spodoptera frugiperda, was first reported on the African continent in early 2016 and reported from Ethiopia in early 2017. The host preference and its biology are not known in Ethiopia. Therefore, the current study was aimed at studying the biology and host preferences of FAW. The experiment was carried out in the greenhouse and wire-house of Ambo Agricultural Research Center from July 2021 to October 2021. The biology of FAW was studied using maize, sorghum, chickpeas, barley, and wheat. The experiments were conducted in the average rearing room temperature of 25.5°C to 37.4°C and relative humidity of 35.33% to 45.46%. Data on egg incubation period, pre-pupal, pupal, egg to adult period, pupal weight, sex ratio, and cannibalism percentage were collected for the biology study. The egg incubation period was between 5 and 8 days. The larval developmental period completed in 14 to 19 days, while pupal stage needed 8 to 9 days. FAW females lay 32-122 eggs in their lifetime. The oviposition period was 2 to 3 days. FAW life cycle ranged from 31 to 38 days at the specified temperature and relative humidity. In terms of the sex ratio of FAW, there was no difference between the tested crops. However, significant (P<0.05) variation was observed with respect to larval cannibalism when reared on different crops. The host preference study was carried out using choice and no-choice experiments on 23 different crops. Data on preferences for oviposition by adult females and for larval feeding were collected. Compared to the other studied host crops, it was discovered that maize, sorghum, swiss chard, teff, elephant grass, and cabbage were the most preferred hosts for larval development and egg laying. The adult female laid eggs on faba bean, soya bean, haricot bean, garlic, and mustard plants, but the eggs did not hatch into larvae. These findings have important implications for understanding the FAW survival, development, and host preference, as well as knowing the best time to plan its effective management.

Evaluation of Botanicals against Rice Case Worm Parapoynx stagnalis Zeller. (Lepidoptera: Pyralidae)

Rice, Oryza sativa L. is the staple food of two thirds of world population. Several insect pests are reported to cause damage to rice crop. Rice case worm, unlike other lepidopteran rice pests, have an aquatic larval period and hence depends on dissolved oxygen in the water drop it carries in its case, made from rice leaf. Application of insecticide spray, does not give much control of this pest. No botanicals are yet reported as effective against this pest. In the present study, six botanicals were tested on rice case worm under laboratory and field conditions. Of the six plants, Anamirta cocculus gave promising results at five percent concentration followed by Glyricida sepium under both field and laboratory conditions.

GALDAR: A genetically encoded galactose sensor for visualizing sugar metabolism in vivo.

Sugar metabolism plays a pivotal role in sustaining life. Its dynamics within organisms is less understood compared to its intracellular metabolism. Galactose, a hexose stereoisomer of glucose, is a monosaccharide transported via the same transporters with glucose. Galactose feeds into glycolysis and regulates protein glycosylation. Defects in galactose metabolism are lethal for animals. Here, by transgenically implementing the yeast galactose sensing system into Drosophila, we developed a genetically encoded sensor, GALDAR, which detects galactose in vivo. Using this heterologous system, we revealed dynamics of galactose metabolism in various tissues. Notably, we discovered that intestinal stem cells do not uptake detectable levels of galactose or glucose. GALDAR elucidates the role for galactokinase in metabolism of galactose and a transition of galactose metabolism during the larval period. This work provides a new system that enables analyses of in vivo sugar metabolism.

Heritability Estimates for Growth Traits and Correlation Analysis between Weight and Metamorphosis Rate in the Bullfrog Rana (Aquarana) catesbeiana

Metamorphosis is a crucial process in the life cycle of Rana (Aquarana) catesbeiana. R. catesbeiana tadpoles, in their short larval period, possess a high survival rate and also a highly competitive ability in the amphibious stage. In actual seed production, the economic traits of larval period and metamorphosis rate are used as quantifiable indicators of quality for individuals and populations, respectively. However, studies of these economic traits in larval cultivation and production are still lacking. In this study, we constructed 40 full-sib families of R. catesbeiana and measured the weight and metamorphosis rate of tadpoles at different developmental stages. Subsequently, we calculated the phenotypic and genetic association between weight and metamorphosis rate in tadpoles and assessed the heritability of these two traits. The heritabilities of weight at three developmental stages were all higher than 0.40 and decreased with advancement of the developmental stage; the heritability of the metamorphosis rate was 0.18 ± 0.20, a moderate level. Correlation analysis of weight and metamorphosis rate at each developmental stage in each tadpole family showed that weight at stages 25-I, 25-II, and 25-III was significantly correlated at the phenotypic level but non-significantly at the genetic level. The metamorphosis rate was only moderately associated with stage 25-III weight (0.38, p < 0.05). The results of this study confirm the importance and transportability of tadpole weight in actual seed production and provide basic data and a potentially optimized direction for the selective breeding of high-metamorphosis-rate bullfrogs.