Body Length Of Larvae Research Articles

Anthropogenic noise disrupts early-life development in a fish with paternal care

Anthropogenic noise is a global pollutant but its potential impacts on early life-stages in fishes are largely unknown. Here, using controlled laboratory experiments, we tested for impacts of continuous or intermittent exposure to low-frequency broadband noise on early life-stages of the common goby (Pomatoschistus microps), a marine fish with exclusive paternal care. Neither continuous nor intermittent noise exposure had an effect on filial cannibalism, showing that males were capable and willing to care for their broods. However, broods reared in continuous noise covered a smaller area and contained fewer eggs than control broods. Moreover, although developmental rate was the same in all treatments, larvae reared by males in continuous noise had, on average, a smaller yolk sac at hatching than those reared in the intermittent noise and control treatments, while larvae body length did not differ. Thus, it appears that the increased consumption of the yolk sac reserve was not utilised for increased growth. This suggests that exposure to noise in early life-stages affects fitness-related traits of surviving offspring, given the crucial importance of the yolk sac reserve during the early life of pelagic larvae. More broadly, our findings highlight the wide-ranging impacts of anthropogenic noise on aquatic wildlife living in an increasingly noisy world.

Morphometric traits of Black Soldier Fly larvae in slaughterhouse waste and rice bran growing medium

This study investigated the effects of utilizing a mixture of slaughterhouse waste and rice bran as a growing medium on the morphometric traits of Black Soldier Fly (BSF) larvae. The research followed a completely randomized design with five treatment groups, namely T0: 100% slaughterhouse waste (control), T1: 75% slaughterhouse waste + 25% rice bran, T2: 50% slaughterhouse waste + 50% rice bran, T3: 25% slaughterhouse waste + 75% rice bran, and T4: 100% rice bran. The morphometric traits examined in this study included the larvae body length at 19 days (LBL19), larvae body width at 19 days (LBW19), larvae body length at 29 days (LBL29), and larvae body width at 29 days (LBW29). The results demonstrated that using slaughterhouse waste as the sole medium (T0) could support the growth of BSF larvae, but the morphometric traits of larvae in T0 were relatively modest. Interestingly, when RB was used to replace SW partially, it had a dose-dependent effect. T1 significantly improved (P < 0.05) LBL19, LBL29, and LBW29. Conversely, the morphometric traits of BSF larvae in T2 and T3 did not exhibit significant changes (P > 0.05) compared to the control. Moreover, the use of T4 significantly enhanced (P < 0.05) all morphometric traits of BSF larvae (LBL19, LBW19, LBL29, and LBW29). In conclusion, this study reveals the significant potential of BSF in managing slaughterhouse waste. Furthermore, employing a growing medium consisting of 75% slaughterhouse waste and 25% rice bran emerges as a practical approach to strike a harmonious balance between effective waste management and fostering the development of BSF larvae.

DNA barcoding of Tribolium castaneum (Coleoptera: Tenebrionidae) from selected states in Nigeria based on mitochondrial DNA sequences

Tribolium castaneum also known as red flour beetle is one of the most important pests of stored grain product with a cosmopolitan distribution in Nigeria and all over the world contributing to food spoilage. The aim of this study was to characterize the T. castaneum by morphometric and molecular analyses. Samples of yam flour with evidence of the red flour beetles present inside were obtained from four locations in Kwara, Kogi, Oyo and Ekiti states in Nigeria. Morphological and molecular identifications of T. castaneum were carried out using standard methods. A dissecting microscope was used to identify the beetles and measurements were taken using ImageJ. Genomic DNA was extracted and checked on 1.5% agarose gel to confirm the presence of DNA. Species-specific primers were used to amplify mitochondrial cytochrome oxidase I (COI) gene of T. castaneum and the PCR amplicon size was also checked on 1.5% agarose. Morphometric measurements showed that the highest mean number (33.00±4.24 mm) of T. castaneum larvae observed was recorded on day 61 in Ilorin and the lowest was in Iwo, Osun state (4.00±0.00 mm) on the same day. The mean of the total body length of larvae from sampling sites was (1.31±0.37 mm) with minimum and (1.63±1.14 mm) maximum lengths respectively. There was no significant difference (p>0.05) between the mean length of the larvae collected from the study locations. Aligned cytochrome oxidase subunit 1 (COI) sequences of 313bp were analyzed. Phylogenetic analysis inferred by maximum likelihood method showed that the T. castaneum sequences analyzed for this study and sequences obtained from GenBank formed a monophyletic group. The molecular and phylogenetic analyses confirmed the presence of a single species of T. castaneum. The results from this study showed low levels of genetic diversity and variability in the studied T. castaneum populations. The observed genetic similarity in T. castaneum could be due to the fact that they were probably from similar origin when compared with those in the GenBank database. However, further studies are needed with more samples to characterize T. castaneum species from stored food grains across Nigeria.

Effect of Ciprofloxacin on the Composition of Intestinal Microbiota in Sarcophaga peregrina (Diptera: Sarcophagidae).

The intestinal bacteria of insects are crucial to the growth and development of the host. It has been found that various physiological processes of insects, such as immune response, metabolism, reproductive ability, and growth and development, involve the gastrointestinal flora. However, many external factors affect the composition of insects' intestinal microorganisms, such as the type of dietary substrate. Sarcophaga peregrina (Robineau-Desvoidy, 1830) (Diptera: Sarcophagidae) is of great significance in medicine and forensic science. In this study, we investigated the effects of ciprofloxacin on the growth and gut microbiota of S. peregrina. The results demonstrated that the maximum body length of larvae was not affected by ciprofloxacin, while the growth rate of body length quickened as the concentration of the drug increased. The weight of the pupa and adult was reduced significantly due to the effect of ciprofloxacin. After analyzing the gut microbiota composition of S. peregrina in different drug groups, it was indicated that Ignatzschineria, Providencia, Wohlfahrtiimonas, Proteus, Myroides, and Bacteroides play important roles in the growth of S. peregrina. However, they still need to be further studied. In general, ciprofloxacin can affect the gut microbial community structure, which in turn affects the fitness of the host.

Toxic Effects of Copper Fungicides on the Development and Behavior of Zebrafish in Early-Life Stages.

Copper-based fungicides have been used to control various plant diseases for more than one hundred years and play very important roles in agriculture. Accumulation of copper in freshwater and environment pose severe threats to human health and the environment. The current study evaluated the developmental and behavioral toxicity of PEG@Cu NCs (copper nanoclusters), Kocide® 3000 (copper hydroxide), and Cu(CH3COO)2 (copper acetate) to zebrafish in early-life stages. The developmental toxicity was evaluated according to the parameters of mortality, hatching rate, autonomous movement and heartbeat of embryos, and body length of larvae. The 9 dpf (days postfertilization)-LC50 (50% lethal concentration) of embryonic mortality was 0.077, 0.174 or 0.088 mg/L, and the 9 dpf-EC50 (effective concentration of 50% embryos hatching) of hatching rate was 0.079 mg/L, 0.21 mg/L and 0.092 mg/L when the embryos were exposed to PEG@Cu NCs, Kocide® 3000 or Cu(CH3COO)2, respectively. Kocide® 3000 and Cu(CH3COO)2 obviously decreased the spontaneous movements, while PEG@Cu NCs had no adverse effects on that of embryos. The reduced heartbeat can return to normal after exposure to PEG@Cu NCs for 96 h, while it cannot recover from Kocide® 3000. In addition, Kocide® 3000 (≥0.2 mg/L), PEG@Cu NCs and Cu(CH3COO)2 with 0.05 mg/L or higher concentration exhibited obvious behavioral toxicity to zebrafish larvae according to the parameters of movement distance, average velocity, absolute sinuosity, absolute turn angle and absolute angular velocity.

Hexavalent Chromium Inhibited Zebrafish Embryo Development by Altering Apoptosis- and Antioxidant-Related Genes.

This study aimed to assess the effects of hexavalent chromium on zebrafish (Danio rerio) embryo development. The zebrafish embryos were treated with solutions containing chromium at different concentrations (0.1, 1, 3.125, 6.25, 12.5, 50, and 100 µg/mL). The development of zebrafish embryos was estimated by the determination of survival rate, heart rate, and the measurement of larvae body length. Real time RT-PCR and Western blot were performed to assess the expression of apoptosis- and antioxidant-related genes. The results showed that the reduced survival rate of zebrafish embryos and larvae was associated with an increase in chromium concentration. The exposure of higher concentrations resulted in a decrease in body length of zebrafish larvae. In addition, a marked increase in heart rate was observed in the zebrafish larvae under chromium treatment, especially at high concentrations. The real-time RT-PCR analysis showed that the transcript expressions for cell-cycle-related genes (cdk4 and cdk6) and antioxidant-related genes (sod1 and sod2) were downregulated in the zebrafish embryos treated with chromium. Western blot analysis revealed the upregulation of Caspase 3 and Bax, while a downregulation was observed in Bcl2. These results indicated that hexavalent chromium induced changes in zebrafish embryo development by altering apoptosis- and antioxidant-related genes.

Growth patterns of saffron cod <i>Eleginus gracilis</i> Tilesius (Gadidae) in the first year of life

Patterns of linear and weight growth of saffron cod in the first year of life are considered on the data of measurements and cited materials for different habitats of this species. The growth curve is approximated by logistic function. Monthly increments for the body length of larvae and fry are about 50–60 % in the first four months of life with the highest growth rate. Then the relative growth decreases significantly in fall-winter and does not exceed 1–4 % to the end of the first year of life. The absolute length increments increase during the first half of the year up to the maximum value of 25–30 mm/month in late summer – early autumn. Saffron cod grow faster in the southern areas of their habitat. The weight growth patterns are different from the linear growth. The weight growth is higher in the first five months of life, with gradual decreasing of the monthly weight increments form 156 % to 105 %. The relative weight increments exceed significantly the length increments in this period. When the body weight reaches app. 5 g, the relative weight increments decrease abruptly, though the absolute increments continue to increase until the 6–8th months of life when they reach 5–6 g per month for fish with body length > 86 mm. The body weight increases by 60 % in this short period of the highest weight growth. Time lag between the peaks of absolute linear growth (in July-September) and weight growth (in September-November) is about 2 months.

An Acyl Carrier Protein Gene Affects Fatty Acid Synthesis and Growth of Hermetia illucens

Acyl carrier protein (ACP) is an acyl carrier in fatty acid synthesis and is an important cofactor of fatty acid synthetase. Little is known about ACP in insects and how this protein may modulate the composition and storage of fatty acids. We used an RNAi-assisted strategy to study the potential function of ACP in Hermetia illucens (Diptera: Stratiomyidae). We identified a HiACP gene with a cDNA length of 501 bp and a classical conserved region of DSLD. This gene was highly expressed in the egg and late larval instars and was most abundant in the midgut and fat bodies of larvae. Injection of dsACP significantly inhibited the expression level of HiACP and further regulated the fatty acid synthesis in treated H. illucens larvae. The composition of saturated fatty acids was reduced, and the percentage of unsaturated fatty acids (UFAs) was increased. After interfering with HiACP, the cumulative mortality of H. illucens increased to 68.00% (p < 0.05). H. illucens growth was greatly influenced. The development duration increased to 5.5 days, the average final body weights of larvae and pupae were decreased by 44.85 mg and 14.59 mg, respectively, and the average body lengths of larvae and pupae were significantly shortened by 3.09 mm and 3.82 mm, respectively. The adult eclosion rate and the oviposition of adult females were also severely influenced. These results demonstrated that HiACP regulates fatty acid content and influences multiple biological processes of H. illucens.

Early Development Of Catfish Larvae Sangkuriang (Clarias gariepinus) From Feed With The Addition Of Curcumin

This study aims to identify the quality of spawning eggs and body length in the early development of catfish larvae from broodstock fed with the addition of curcumin. This research was conducted on October 22 2022 for 2 weeks on Jl. Great Aluminum No. 37, Tj. Mulia Hilir, Kec. Medan Deli, Medan City, North Sumatra 20241. The method used in this research is an experimental method. The sample used is sangkuriang catfish seeds (Clarias gariepinus) obtained from catfish breeding/cultivation. There are 2 pairs in total. Each pair consists of male and female catfish which are placed in the same pond but have been partitioned off. One pair of sangkuriang catfish will be given feed in the form of pellets with the addition of curcumin while the other pair will only be given pellets. The treatment in giving curcumin is 50% of the feed weight once a day the average body length of larvae has a body length and body weight that is higher than curcumin was not given so that the 0% curcumin treatment had the lowest body length. The increase in the diameter of the spawning larvae in the supplemented treatment group curcumin can be caused due to the bioactivity of curcumin as a hepatoprotector, and antioxidants. Curcumin supplementation is 50% of the total feed given to the parent showed more optimal results than the treatment other.

Effects of different light conditions on growth, muscle nutrients content, and clock gene circadian expression of Takifugu rubripes

Basic knowledge about the effect of light on fish in needed to improve their development, survival, and growth to increase aquaculture efficiency. In this study, the effects of light photoperiods (light (L): dark (D) = 12:12 and 16:8) and spectrum (full spectrum (W), blue (B) and yellow (Y)) on Takifugu rubripes larvaes were assessed from 20 to 80 days after hatching (dah). At 50 dah, the body length of larvae exposed to Y16:8 and B16:8 was significantly higher than that in the W16:8 group (P < 0.05). The wet weight of larvae reared under B16:8 was significantly higher than that under B12:12 (P < 0.05). The wet weight of larvae exposed to B12:12 was significantly higher than that in the W12:12, and the wet weight of larvae exposed to B16:8 was significantly higher than that of larvae exposed to W16:8 and Y16:8 (P < 0.05). At 80 dah, the body length and wet weight of larvae reared under 12:12 were significantly higher than those of larvae reared under 16:8 in the white and yellow LEDs groups (P < 0.05). Additionally, the biochemical composition of muscle were affected, the levels of DHA and EPA+DHA were significantly higher in the W16:8 and B16:8 groups, compared to the W12:12 and B12:12 groups, respectively (P < 0.05). Since light is the predominant signal for the entrainment of circadian oscillators and controls growth as a zeitgeber, the expression of arylalkylamine N-acetyltransferase 2 (annat2), crytochrome 2 (cry2), peroid1 (per1) and per3 in the brain were also been measured. The long photoperiod 16:8 delayed the acrophases of annat2, and blue light decreased the expression of cry2 and per3. These results provide the theoretical basis for using LED lights in aquaculture production of T. rubripes larvae.

Environmentally relevant concentrations of microplastics modulated the immune response and swimming activity, and impaired the development of marine medaka Oryzias melastigma larvae

Microplastics (MPs), due to their impacts on the ecosystem and their integration into the food web either through trophic transfer or ingestion directly from the ambient environment, are an emerging class of environmental contaminants posing a great threat to marine organisms. Most reports on the toxic effects of MPs exclusively focus on bioaccumulation, oxidative stress, pathological damage, and metabolic disturbance in fish. However, the collected information on fish immunity in response to MPs is poorly defined. In particular, little is known regarding mucosal immunity and the role of mucins. In this study, marine medaka (Oryzias melastigma) larvae were exposed to 6.0 µm beads of polystyrene microplastics (PS-MPs) at three environmentally relevant concentrations (102 particles/L, 104 particles/L, and 106 particles/L) for 14 days. The experiment was carried out to explore the developmental and behavioural indices, the transcriptional profiles of mucins, pro-inflammatory, immune, metabolism and antioxidant responses related genes, as well as the accumulation of PS-MPs in larvae. The results revealed that PS-MPs were observed in the gastrointestinal tract, with a concentration- and exposure time-dependent manner. No significant difference in the larval mortality was found between the treatment groups and the control, whereas the body length of larvae demonstrated a significant reduction at 106 particles/L on 14 days post-hatching. The swimming behaviour of the larvae became hyperactive under exposure to 104 and 106 particles/L PS-MPs. In addition, PS-MP exposure significantly up-regulated the mucin gene transcriptional levels of muc7-like and muc13-like, however down-regulated the mucin gene expression levels of heg1, muc2, muc5AC-like and muc13. The immune- and inflammation and metabolism-relevant genes (jak, stat-3, il-6, il-1β, tnf-а, ccl-11, nf-κb, and sod) were significantly induced by PS-MPs at 104 and 106 particles/L compared to the control. Taken together, this study suggests that PS-MPs induced inflammation response and might obstruct the immune functions and retarded the growth of the marine medaka larvae even at environmentally relevant concentrations.

Effects of chronic exposure to microcystin-LR on life-history traits, intestinal microbiota and transcriptomic responses in Chironomus pallidivittatus

Microcystins (MCs) are the most widely distributed cyanobacterial toxins that can exert adverse effects on aquatic organisms, but aside from the study of the harmful effect of cyanobacterial blooms, little is known about the effect of released MCs on the growth and development of chironomid larvae. To assess the harmful effect and the toxic mechanism of MCs on midges, the life-history traits, intestinal microbiota, and transcriptome of Chironomus pallidivittatus were analyzed after chronic exposure to 30 μg/L of MC-LR. Exposure inhibited larvae body length by 35.61% and wet weight by 21.92%, increased emergence time of midges, damaged mitochondria in the intestine, promoted oxidative stress, dysregulated lipid metabolism of chironomid larvae, and increased detoxification enzymes glutathione S-transferase (GST) and superoxide dismutase (SOD) by 32.44% and 17.41%, respectively. Exposure also altered the diversity and abundance of the intestinal microbiota, favoring pathogenic and MC degradation bacteria. RNA sequencing identified 261 differentially expressed genes under MC-LR stress, suggesting that impairment of the peroxisome proliferator-activated receptor signaling pathway upregulated fatty acid biosynthesis and elongation to promote lipid accumulation. In addition, exposure-induced detoxification and antioxidant responses, indicating that the chironomid larvae had the potential ability to resist MC-LR. To our knowledge, this is the first time that lipid accumulation, oxidative stress, and detoxification have been studied in this organism at the environmentally relevant concentration of MC-LR; the information may assist in ecological risk assessment of cyanobacterial toxins and their effects on benthic organisms.

Sublethal doses of broflanilide prevents molting in the fall armyworm, Spodoptera frugiperda via altering molting hormone biosynthesis

Broflanilide is a novel insecticide with a unique mode of action on the insect GABA receptor and is registered worldwide for the control of agricultural pests. It shows high efficacy in controlling the fall armyworm (FAW) Spodoptera frugiperda, which is a destructive pest to various crops. FAW was exposed to sublethal concentrations of broflanilide to determine its impact on insect development. Sublethal doses (LD10 and LD30) caused failure of ecdysis, reduced body length of larvae, malformation of pupae, and vestigial wing formation in adults. Also, broflanilide at LD30 significantly reduced the amount of molting hormone (MH). After exposure to LD10 or LD30 broflanilide, expression of five Halloween genes, which participate in MH biosynthesis, were found to be altered. Specifically, the transcript levels of SfrCYP307A1 (Spook), SfrCYP314A1 (Shade) and SfrCYP315A1 (Shadow) in 3rd day larvae were significantly decreased as well as SfrCYP302A1 (Disembodied) and SfrCYP306A1 (Phantom) in 5th day pupae. In contrast, the transcript levels of SfrCYP302A1 in 3rd day larvae, SfrCYP307A1 and SfrCYP314A1 in 5th day pupae, and SfrCYP306A1, SfrCYP307A1 and SfrCYP315A1 in 0.5th day adults were significantly increased. Our results demonstrate that broflanilide caused the failure of ecdysis in FAW possibly by influencing the intake of cholesterol through inhibition of feeding and also via altering expression of genes important for MH biosynthesis.

Enhanced growth without accelerated puberty in fish: A role for the melanocortin system

In two swordtail species of the genus Xiphophorus, onset of puberty in males and females, fecundity in females, and adult size in males are modulated by sequence polymorphism and gene copy-number variation at the P locus affecting the type 4 melanocortin hormone receptor (Mc4r). The involvement of Mc4r in regulating the onset of puberty outside the genus Xiphophorus remains unclear. In this study we used a transgenic line overexpressing asip1 (asip1-Tg), an endogenous antagonist of both type 1 melanocortin hormone receptor (Mc1r) and Mc4r, to investigate the relevance of the melanocortin system on the onset of puberty and adult reproductive performance in zebrafish (Danio rerio). Comparison of growth, puberty and reproductive performance between wild-type (WT) and asip1-Tg zebrafish revealed that a decreased activity of the melanocortin system did not change the timing of puberty but significantly delayed early growth of transgenic animals. Hatching time was postponed in asip1-Tg fish and they were significantly smaller than their WT siblings at 75 dpf, despite showing enhanced linear growth after having completed puberty. asip1-Tg females produced 1.38 times more eggs but spawned less frequently, and their eggs had showed a 0.89-fold smaller diameter but a 1.04-fold increase in larvae body length at hatching. Therefore, we demonstrate that asip-tg zebrafish do not reach puberty earlier than WT counterparts as it could be expected considering the enhanced length and weight growth during early adulthood. This is so because the effects of transgene on growth are noticeable after a threshold length, when puberty has already been reached. Data show that the inhibition of melanocortin system via asip overexpression is an excellent strategy to promote growth, in absence of obesity, by enhancing food efficiency but without accelerating puberty timing. Data here presented provides a deeper characterization of the phenotype induced by the decreased activity of the melanocortin system in fish thus providing an excellent strategy for future aquaculture especially because U.S. Food and Drug Association has recently approved transgenic fish trading.

Keeping, Breeding, and Maintenance of Zooculture of the Ladakh Toad, &lt;i&gt;Bufotes latastii&lt;/i&gt; (Boulenger, 1882)

In this paper we present results of laboratory reproduction of the Ladakh toad (Bufotes latastii) for three generations. Two pairs of animals, which were collected in April of 2013 in Jammu and Kashmir (India), became founders of a laboratory population. The first female gave offspring four times, while the second only once. The number of eggs in clutches obtained from the first female was 6804 – 10149 and from the second was 4080 eggs. Males, which were born in laboratory, started to vocalize at the age of 3 – 4 months after metamorphosis and at the age of one year successfully reproduced. Females become mature at the two-year age only. Thus, B. latastii is a fast-growing and early-maturing species. The number of eggs in clutches of 2-year-old laboratory females ranged from 31 to 6420 eggs (n = 28) and 3-year-old females from 19 to 6859 eggs (n = 21). Clutches were single- or double-row strings. The average thickness of egg strings was 3.2 – 5.9 mm. The diameter of eggs was 0.8 – 1.9 mm. The duration of embryonic development (until separation of pre-larvae from egg strings) was 2 – 5 days. The total body length of pre-larvae was 2.0 – 4.3 mm. The first larvae that started swimming and feeding were observed within 2 – 3 days after separation of pre-larvae from egg strings. The body length of larvae at the time of start of exogenous feeding was 2.9 – 4.3 mm and the length of tail was 1.6 – 6.3 mm. The total duration of embryogenesis was 4 – 8 days, larval development was 86 – 125 days, and overall development was 90 – 127 days.

Silver Nanoparticles in Zebrafish (Danio rerio) Embryos: Uptake, Growth and Molecular Responses.

Silver nanoparticles (AgNPs) are widely used in commercial applications as antimicrobial agents, but there have recently been increasing concerns raised about their possible environmental and health impacts. In this study, zebrafish embryos were exposed to two sizes of AgNP, 4 and 10 nm, through a continuous exposure from 4 to 96 h post-fertilisation (hpf), to study their uptake, impact and molecular defense responses. Results showed that zebrafish embryos were significantly impacted by 72 hpf when continuously exposed to 4 nm AgNPs. At concentrations above 0.963 mg/L, significant in vivo uptake and delayed yolk sac absorption was evident; at 1.925 mg/L, significantly reduced body length was recorded compared to control embryos. Additionally, 4 nm AgNP treatment at the same concentration resulted in significantly upregulated hypoxia inducible factor 4 (HIF4) and peroxisomal membrane protein 2 (Pxmp2) mRNA expression in exposed embryos 96 hpf. In contrast, no significant differences in terms of larvae body length, yolk sac absorption or gene expression levels were observed following exposure to 10 nm AgNPs. These results demonstrated that S4 AgNPs are available for uptake, inducing developmental (measured as body length and yolk sac area) and transcriptional (specifically HIF4 and Pxmp2) perturbations in developing embryos. This study suggests the importance of particle size as one possible factor in determining the developmental toxicity of AgNPs in fish embryos.

Toxicity of microbial insecticides toward the non-target freshwater insect Chironomus xanthus.

Commercial formulations based on Bacillus thuringiensis subs. kurstaki (Btk) and Beauveria bassiana (Bb) are commonly used microbial insecticides in Brazil and other tropical regions. However, and despite being considered environmentally friendly, their use generates concerns regarding possible adverse ecological effects in freshwater ecosystems. Here, we evaluate the effects of these bioinsecticides on the tropical aquatic dipteran Chironomus xanthus under laboratory conditions. After laboratory exposures to these compounds 48-h median lethal concentration (LC50 ) values of 1534 μg a.i./L for Btk and of 6.35 μg a.i./L for Bb were estimated. Chronic assays revealed different sublethal effects: Btk-based bioinsecticide exposure reduced C. xanthus growth [lowest observed effect concentration (LOEC) was 126 μg a.i./L for head width], decreased emergence rate (LOEC = 8 μg a.i./L) and increased immunological response (LOEC = 50 μg a.i./L) measured as total hemocyte count in larvae hemolymph. Exposure to low concentrations of Bb-based insecticide also reduced C. xanthus growth (LOEC = 0.07 μg a.i./L for larvae body length measurements), and emergence rate (LOEC = 0.28 μg a.i./L), despite no clear effects on the total hemocyte counts. Our results suggest that low concentrations of Btk and Bb bioinsecticides are toxic to C. xanthus. Given their widespread use and occurrence in tropical freshwater systems, research is needed to evaluate the potential effects of these compounds concerning natural freshwater insect communities and ecosystem functioning. © 2019 Society of Chemical Industry.

Temperature-dependent toxicity of acetaminophen in Japanese medaka larvae

Because of its analgesic properties, acetaminophen (AAP) is widely used to relieve headache. AAP is generally considered safe for humans, but its effects on aquatic organisms are not well known. Here, we have hypothesis that effects of AAP on aquatic organisms would be environmental temperature dependent, because their physiological function depend on the temperature. To test this hypothesis, we used medaka (Oryzias latipes) as a model, because they can live at a wide range of temperatures (0–40 °C). We exposed medaka larvae to 0 (control), 50, or 150 mg/L of AAP at 15, 25 (optimal temperature), or 30 °C for 4 days. Egg yolk absorption was accelerated with raising temperature at any AAP dose. AAP exposure did not have biologically significant effects on survival ratio and body length of larvae at any tested temperature or dose, but heart rate decreased as the dose of AAP and environmental temperature increased. In addition, as the temperature increased, amount of ATP in individual larvae increased in control group, but decreased in AAP exposed group. Subsequently, exposure to 150 mg/L of AAP at 30 °C decreased the number of red blood cells in the gills; we used 150 mg/L of AAP in subsequent hematological and histological analyses. Hematological analysis showed that rising temperature increased the proportion of morphologically abnormal red blood cells in AAP-exposed larvae, suggesting that AAP induced anemia-like signs in larvae. Histological observation of the kidney, which is a hematopoietic organ in fish, revealed no abnormalities. However, in the liver, which is responsible for drug metabolism, the proportion of vacuoles increased with increasing temperature. Although the exposure concentration we tested was higher than environmentally relevant concentrations, our data indicated that rising temperature enhances the toxicity of AAP to medaka larvae, suggesting an ecological risk of AAP due to global warming.

Cardiovascular toxicity and anxiety-like behavior induced by deltamethrin in zebrafish (Danio rerio) larvae

Deltamethrin is widely used because of its low toxicity and high efficiency. Although its potential toxicity has been reported, its effects on cardiovascular system and motor behavior and its underlying mechanisms have remained unclear. In this study, the effects of deltamethrin on the development, cardiovascular system and motor behavior of zebrafish larvae and their possible mechanisms were evaluated using the transgenic zebrafish Tg (kdrl:mCherry) and Tg(myl7:GFP). At 72 hpf, the body length of larvae shortened, the head and eye area decreased, and the hatching rate increased. Acridine orange staining showed that treated zebrafish larvae produced different degrees of apoptosis in the head, body, heart and tail regions. Quantitative fluorescence intensity showed a dose-dependent increase in apoptosis signal, indicating that deltamethrin could induce apoptosis. Confocal images and fluorescence intensity quantification of red fluorescent protein-labeled vascular endothelial cell and green fluorescent protein-labeled transgenic zebrafish more clearly reflected the dose-dependent cardiac and vascular morphology and the damage caused by deltamethrin. Deltamethrin significantly induced vascular endothelial growth factor flk1 and fli-1, cardiac development-related gene myl7 decreased in a dose-dependent manner. In addition, deltamethrin increased the thigmotaxis of zebrafish larvae, causing anxiety-like behavior. Our study showed that deltamethrin could cause developmental toxicity, apoptosis, cardiovascular system damage and anxiety-like behavior, which provided a reference for the use of deltamethrin in agricultural production.

Larvicidal Effectiveness of Azolla pinnata against Aedes aegypti (Diptera: Culicidae) with Its Effects on Larval Morphology and Visualization of Behavioural Response.

Dengue is vector-borne diseases with 390 million infections per year extending over 120 countries of the world. Aedes aegypti (L.) (Diptera: Culicidae) is a primary vector for dengue viral infections for humans. Current focus on application of natural product against mosquito vectors has been the main priority for research due to its eco-safety. The extensive use of chemical insecticides has led to severe health problems, environmental pollution, toxic hazards to human and nontarget species, and development of insecticide resistance on mosquitoes. Azolla pinnata is an aquatic fern and predominantly used as feed in poultry industry and as fertilizer in agricultural field for enhancing the fertility of rice paddy soil. The present study was conducted to explore the larvicidal efficacy of A. pinnata using fresh and powdered form against late third-stage larvae (6 days, 5 mm in larvae body length) of Ae. aegypti (L.) (Diptera: Culicidae). The larvicidal bioassays were performed using World Health Organization standard larval susceptibility test method for different concentration for powdered and fresh A. pinnata. Powdered A. pinnata concentration used during larvicidal bioassay ranges from 500ppm to 2000ppm; meanwhile, fresh A. pinnata ranges from 500ppm to 9,000,000 ppm. The highest mortality was at 1853 ppm for powdered A. pinnata compared with fresh A. pinnata at 2,521,535 ppm, while the LC50 for both powdered and fresh A. pinnata recorded at 1262 ppm and 1853 ppm, respectively. Finally, the analysis of variance (ANOVA) showed significant difference on Ae. aegypti larval mortality (F=30.439, df=1, p≤0.001) and concentration (F=20.002, df=1, p≤0.001) compared to powdered and fresh A. pinnata at 24-hour bioassay test. In conclusion, the powdered A. pinnata serves as a good larvicidal agent against Ae. aegypti (L.) (Diptera: Culicidae) and this study provided information on the lethal concentration that may have potential for a more eco-friendly Aedes mosquito control program.