Ultrastructural variations in Lethocerus niloticum (Insecta: Hemiptera) caused by pollution in Lake Mariut, Alexandria, Egypt

Imidacloprid-induced mortality, histopathology and biochemical impairments in the larvae of oriental latrine fly (Chrysomya megacephala)

The concentration-mortality response of third instar larvae of Chrysomya megacephala (Diptera: Calliphoridae) to a synthetic insecticide, imidacloprid, and its impact on histopathological, histochemical, and biochemical parameters were determined in laboratory assays. Larvae displayed a concentration and time-dependent mortality response for the insecticide. Histopathological studies exhibited quite noticeable modifications in the epithelial cells, peritrophic membrane, basement membrane and muscular layer of the larval midgut. The ultrastructural analysis demonstrated alterations in nuclei, lipid spheres, microvilli, mitochondria, rough endoplasmic reticulum and lysosomes. In addition, histochemical tests on the midgut were performed, which revealed a strong reaction for proteins and carbohydrates in the control group and a weak reaction in the group exposed to imidacloprid in a dose and time-dependent manner. Imidacloprid also caused a significant reduction in the total midgut content of carbohydrates, proteins, lipids and cholesterol. Larvae treated with imidacloprid also showed a reduction in the activities of acid and alkaline phosphatases at all concentrations compared to untreated larvae.

Molecular characteristics, polymorphism and expression analysis of mhc Ⅱ in yellow catfish(pelteobagrus fulvidraco)responding to Flavobacterium columnare infection

The major histocompatibility complex (MHC) is an important component of the immune system of vertebrates, which plays a vital role in presenting extrinsic antigens. In this study, we cloned and characterized the mhc ⅡA and mhc ⅡB genes of yellow catfish Pelteobagrus fulvidraco. The open reading frames (ORFs) of mhc ⅡA and mhc ⅡB genes were 708 bp and 747bp in length, encoding 235 and 248 amino acids, respectively. The structure of mhc ⅡA and mhc ⅡB includes a signal peptide, an α1/β1 domain, an α2/β2 domain, a transmembrane region and a cytoplasmic region. Homologous identity analysis revealed that both mhc ⅡA and mhc ⅡB shared high protein sequence similarity with that of Chinese longsnout catfish Leiocassis longirostris. mhc ⅡA and mhc ⅡB showed similar expression patterns in different tissues, with the higher expression level in spleen, head kidney and gill and lower expression in liver, stomach, gall bladder and heart. The mRNA expression level of mhc ⅡA and mhc ⅡB in different embryonic development stages also showed the similar trends. The higher expression was detected from fertilized egg to 32 cell stage, low expression from multicellular period to 3 days post hatching (dph), and then the expression increased to a higher level from 4 dph to 14 dph. The mRNA expression levels of mhc ⅡA and mhc ⅡB were significantly up-regulated not only in the body kidney and spleen, but also in the midgut, hindgut, liver and gill after challenge of Flavobacterium columnare. The results suggest that Mhc Ⅱ plays an important role in the anti-infection process of yellow catfish P. fulvidraco.

Pollution impacts on water bugs (Nepomorpha, Gerromorpha): state of the art and their biomonitoring potential

As water pollution poses an increasing risk worldwide, it is timely to assess the achievements of the aquatic macroinvertebrate ecotoxicology to provide a sound basis for the discipline's future and support the development of biomonitoring. Aquatic and semi-aquatic bugs (Hemiptera: Nepomorpha, Gerromorpha) are ubiquitous in almost all water types, sometimes in high densities, and play a significant role in organic material turnover and energy flow. Nevertheless, they are ignored in the water pollution biomonitoring schemes. Here, based on 300 papers, we review and evaluate the effects of chemical pesticides, microorganism-derived pesticides, insecticides of plant origin, heavy metals, eutrophication, salinisation and light pollution which are summarised for the first time. Our review encompasses the results of 100 laboratory and 39 semi-field/field experiments with 47 pesticides and 70 active ingredients. Pyrethroids were found to be more toxic than organochlorine, organophosphate and neonicotinoid insecticides to water bugs, like other macroinvertebrate groups. Additionally, in 10 out of 17 cases, the recommended field concentration of the pesticide was higher than the LC50 values, indicating potential hazards to water bugs. The recommended field concentrations of pesticides used in mosquito larvae control were found non-toxic to water bugs. As very few replicated studies are available, other findings on the effects of pesticides cannot be generalised. The microorganism-derived pesticide Bti appears to be safe when used at the recommended field concentration. Data indicates that plant-derived pesticides are safe with a high degree of certainty. We have identified three research areas where water bugs could be better involved in water biomonitoring. First, some Halobates spp. are excellent, and Gerris spp. are promising sentinels for Cd contamination. Second, Micronecta and, to a certain extent, Corixidae species composition is connected to and the indicator of eutrophication. Third, the species composition of the Corixidae is related to salinisation, and a preliminary method to quantify the relationship is already available. Our review highlights the potential of water bugs in water pollution monitoring.

An SNP at the target site of cid-miR-nov-1043 in the TOLLIP 3' UTR decreases mortality rate in grass carp subjected to ENU-induced mutagenesis following grass carp reovirus infection

N-ethyl-N-nitrosourea (ENU) selection is a useful technique to generate new mutations that may cause some functional changes in the gene. Through our previous genomic bulked segregant analysis (BSA), one single nucleotide polymorphism (SNP) at the 3' UTR of Toll interacting protein gene (TOLLIP^982T>C) was identified in grass carp (Ctenopharyngodon idella) subjected to ENU-induced mutagenesis. We found that the overexpression of cid-miR-nov-1043 mimics significantly suppressed the luciferase activity of the TOLLIP 3' UTR, but TOLLIP^982T>C mutation at the target site can decrease the binding affinity between the miRNA cid-miR-nov-1043 and TOLLIP 3' UTR, reducing the inhibition of TOLLIP mRNA transcription in grass carp subjected to ENU-induced mutagenesis. More importantly, we demonstrated that TOLLIP mRNA transcription levels in the gills, liver, kidney and the isolate white cells of the mutant grass carp were significantly (p < 0.01) higher than those in the corresponding tissues from the wild-type grass carp following infection with Grass Carp Reovirus (GCRV) for seven days, while the downstream gene of TOLLIP transforming growth factor β-activated kinase 1 (TAK1) and TAK1-binding protein 1 (TAB1), were higher expressed in wild-type grass carp. As a negative regulator in the pro-inflammatory pathway of NF-κB, TOLLIP inhibits the excessive inflammation in ENU grass carp after GCRV infection. Consistent with the TOLLIP expression, histopathological results demonstrated more severe inflammation in wild-type grass carp, compared to the TOLLIP^982T>C mutant grass carp on the seventh day. Severe inflammation will lead to thoroughly infiltration of chloride and inflammatory cells in the gill filaments. This seriously hindered the exchange of oxygen, which ultimately disrupted blood circulation. Meanwhile, the survival rate of the mutant grass carp was significantly (p < 0.01) higher than that of the wild-type grass carp, indicating that the TOLLIP^982T>C mutants showed strong anti-viral abilities. Our results revealed that an SNP in the TOLLIP 3' UTR may contribute to the suppression of serve inflammation subjected to ENU-induced mutagenesis following GCRV infection, which may be helpful for future resistant breeding development of grass carp.

The predominant role of mucosal immunoglobulin IgT in the gills of rainbow trout (Oncorhynchus mykiss) after infection with Flavobacterium columnare

Columnaris disease, induced by Flavobacterium columnare, seriously affects the health of freshwater fish species and damages the mucosal tissues, such as the fins, skin, and gills. Teleosts represent the first bony vertebrate to contain both innate and adaptive immune responses against pathogens. So far, three immunoglobulin isotypes (IgM, IgD, and IgT/IgZ) have been identified in teleost fish, and IgT in mucosal tissues of teleost fish was reported to perform a similar function to IgA in mammals during parasitic infection. However, very limited information is known about the function of IgT in gill mucosal tissues during bacterial infection. In the present study, rainbow trout (Oncorhynchus mykiss) was infected with F. columnare (Fc) via immersion. After Fc infection, the gill structure of rainbow trout showed serious hyperplasia symptoms on the secondary lamellae at 12 h post infection (hpi). Moreover, the mRNA expression levels of NOS2 and cathelicidin-1 were significantly upregulated immediately at 12 hpi and showed high expression throughout the experiment. IgT and IgM showed much higher mRNA expression levels at 28 days post infection (dpi) and 75 dpi, while IgD only showed high mRNA expression levels at 28 dpi. Importantly, the accumulation of IgT⁺ B cells and strong bacteria-specific IgT responses were detected in the gill lamellae of both infected fish (28 dpi) and survivor fish (75 dpi). Overall, our results suggest that IgT and IgT⁺ B cells play a central role in the adaptive immune responses of fish gill mucosa against bacterial infection.

Gills as morphological biomarkers in extensive and intensive rainbow trout (Oncorhynchus mykiss, Walbaum 1792) production technologies

We investigated environmental impacts on rainbow trout (Oncorhynchus mykiss) reared at fish farms with either extensive technology, in a flow-through system (FTS, n = 3), or intensive technology, in a recirculating aquaculture system (RAS, n = 3). All fish were fed the same rations. Fish were caught in spring and autumn (body mass, 501-750 g) from these six farms. We performed macroscopic (intact fish) and microscopic (gills stained with haematoxylin/eosin) examinations. Lesions were categorised based on the type and location of structural abnormalities. The histopathological index (HAI) was calculated, and each lesion was scored. Fish reared in FTS or RAS were compared for the prevalence of morphological lesions. Gill epithelial hypertrophy and hyperplasia comprised 73% (RAS) to 79% (FTS) of all morphological abnormalities. In spring and autumn, lesions comprised, respectively, 11 and 18% (FTS) and 16 and 10% (RAS) mucous and chloride cell abnormalities and 8 and 4% (FTS) and 10 and 3% (RAS) blood vessel abnormalities. Diffuse, irreversible gill lesions were observed sporadically in all fish. Gill epithelium received the most exposure to environmental pathogens. HAIs indicated that normal gill architecture and minor lesions predominated in all fish. However, among trout caught in spring, moderate and extensive changes in gills occurred more commonly with RAS (34%) than with FTS (17%). Trout caught in autumn displayed no great differences. These results indicated that FTS prepared fish better than RAS for wintering. Moreover, we showed that gills were an excellent biomarker for analysing the impact of extensive and intensive production environments on rainbow trout.

Impact of agrochemicals on non-target species: Calathus fuscipes Goeze 1777 (Coleoptera: Carabidae) as model

Carabid beetles are important in the biological control of arable crop pests. Agricultural practices can produce over time a delayed toxic effect at the organismal and population levels and can compromise the survival on these species. In this research, we quantified the cumulative sublethal effect on body size, Malpighian tubules and immune responses in Calathus fuscipes adults living in the potato field and exposed to lambda-cyhalothrin and cymoxanil-based commercial formulates. Reductions of morphological parameters such as body, pronotum and elytron in both males and females from the potato field indicated that the pre-imaginal stages (larvae and pupae) suffer the sublethal effects of exposure to the larvicide control action of lambda-cyhalothrin. Ultrastructural alterations recorded in Malpighian tubules at the level of plasma membrane, mitochondria and nucleus indicated the reduction of the detoxification capability. The basal phenoloxidase and lysozyme-like enzyme activities have measured as markers of immune competence. Spectrophometric analyses showed that the chronic exposure in field causes an increase of basal phenoloxidase enzyme activity, while the lytic activity of haemolymph was not affected. As a result, the use of larvicides and fungicides have a harmful effect on beneficial species such C. fuscipes living in the soil of potato fields. These morphological and physiological results recorded at the organismal level can provide useful information of effects at the population and community levels to preserve the biodiversity of agroecosystem.

X-ray metal assessment and ovarian ultrastructure alterations of the beetle, Blaps polycresta (Coleoptera, Tenebrionidae), inhabiting polluted soil

X-ray analysis was applied to estimate the percentages of heavy metals in ovarian tissues of the tenebrionid beetle, Blaps polycresta. Calcium, phosphorus, sulfur, cadmium, copper, and zinc were the most common detected metals in ovaries of insects collected from reference and polluted sites. Only cadmium showed significantly higher percentages in the polluted ovaries compared with the reference ones. Ultrastructure investigation revealed severe alterations in polluted ovaries both in the tropharium and in the vitellarium. Contraction of nuclear membrane of trophocytes was observed; therefore, cavities and spaces appeared in the cytoplasm followed by nuclear pyknosis. In the vitellarium, fragmentation of chromatin materials in nuclei of the follicular cells was detected. The cytoplasm was poor in the rough endoplasmic reticulum and mitochondria. Damage of yolk bodies occurred in addition to break off in the layer of microvilli. Accumulation of electron-dense vesicles and multivesicular bodies were observed in both reference and polluted ovaries. These alterations in ovarian ultrastructure of B. polycresta show the severe impact of cadmium pollution on cell organelles of insects and could be used as an interesting tool for monitoring heavy metals inside the body organs due to soil pollution.

Effects of abamectin and deltamethrin to the foragers honeybee workers of Apis mellifera jemenatica (Hymenoptera: Apidae) under laboratory conditions

This study aimed at evaluating the toxicity of some insecticides (abamectin and deltamethrin) on the lethal time (LT₅₀) and midgut of foragers honeybee workers of Apis mellifera jemenatica were studied under laboratory conditions. The bees were provided with water, food, natural protein and sugar solution with insecticide (concentration: 2.50 ppm deltamethrin and 0.1 ppm abamectin). The control group was not treated with any kind of insecticides. The mortality was assessed at 1, 2, 4, 6, 12, 24, 48, and 72 hour (h) after insecticides treatment and period to calculate the value of lethal time (LT₅₀). But the samples the histology study of midgut collected after 24 h were conducted by Scanning Electron Microscope. The results showed the effects of insecticides on the current results show that abamectin has an adverse effect on honeybees, there is a clear impact on the lethal time (LT₅₀) was the abamectin faster in the death of honeybee workers compared to deltamethrin. Where have reached to abamectin (LT₅₀ = 21.026) h, deltamethrin (LT₅₀ = 72.011) h. However, abamectin also effects on cytotoxic midgut cells that may cause digestive disorders in the midgut, epithelial tissue is formed during morphological alterations when digestive cells die. The extends into the internal cavity, and at the top, there is epithelial cell striated border that has many holes and curves, abamectin seems to have crushed the layers of muscle. Through the current results can say abamectin most toxicity on honeybees colony health and vitality, especially foragers honeybee workers.

Toxic effects of glyphosate-based herbicide, Excel Mera 71 on gill, liver, and kidney of Heteropneustes fossilis under laboratory and field conditions

The effects of glyphosate-based herbicide Excel Mera 71 under field and laboratory conditions were investigated to evaluate the pathological symptoms through light and electron microscopic study in the gill, liver, and kidney of Heteropneustes fossilis (Bloch) for a period of 30 days. Histological alterations like hypertrophy and fusion in secondary lamellae, damage in chloride cells were more prominent in laboratory conditions under light microscopy. Topological changes such as complete loss of microridges, swelling, and irregular arrangement of microridges in the gills were prominent under scanning electron microscopic study under laboratory conditions. Transmission electron microscopy (TEM) study depicted vacuolation and degeneration in chloride cells, dilation in rough endoplasmic reticulum (RER), and mitochondria in gill epithelium. The liver showed enlarged and pyknotic hepatocytes, vacuolation, excess fat deposition, and necrosis under laboratory conditions, while enlarged acentric nuclei, increased sinusoidal space, and less vacuolation in cytoplasm were observed under field conditions. TEM displayed cytoplasmic vacuolation and a reduced number of endoplasmic reticulum and glycogen droplets in the laboratory, but this was less pronounced under field conditions. In the kidneys, loss of hematopoietic tissue, degenerative changes in glomeruli, proximal and distal convoluted tubule, and epithelial cell lining of the renal tubules were comparatively less prominent under field conditions. Under TEM, epithelial cell necrosis, endoplasmic reticulum fragmentation, and mitochondrial degeneration were more prominent under laboratory conditions. The present study evaluated the comparative toxicity under field and laboratory conditions under long-term exposure to glyphosate herbicide and identified pathological responses as indicators in monitoring the herbicidal contamination in aquatic ecosystems.

Culiseta subochrea as a bioindicator of metal contamination in Shadegan International Wetland, Iran (Diptera: Culicidae)

The quantity of some trace metals of mosquito larvae in Shadegan International Wetland from Iran was evaluated. Water, waterbed sediment, and mosquito larvae samplings were carried out from an urban site in the east of the wetland, using standard methods in December 2011. The identified Culiseta subochrea (Edwards) and Aedes caspius s.l. (Pallas) larvae, water, and waterbed sediment samples were analyzed for As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Pb, and Zn trace metals using standard preparation and isolation procedure. Result showed that the waterbed sediment and Cu. subochrea larvae are polluted with all trace metals investigated except As and Hg. The trace metals bioaccumulated in the Cu. subochrea larvae range from 31.78 at the lowest level for Cr to 3822.7 at the highest level for Cd. In a conclusion, this is the first report confirmed that Cu. subochrea likely used as a bioindicator to trace metal pollution in marine ecosystems in the world, especially wetlands.

Toxicological and histopathological effects of boric acid on Atta sexdens rubropilosa (Hymenoptera: Formicidae) workers

The current study compared the toxicity of different concentrations of boric acid in adult workers of Atta sexdens rubropilosa Forel (Hymenoptera: Formicidae), with toxicological bioassays, and examining the dose-dependent and time-dependent histopathological changes, of the midgut, Malpighian tubules, and postpharyngeal glands. Our results revealed the importance of conducting toxicological bioassays combined with morphological analyses of the organs of ants chronically exposed to insecticides used in commercial ant baits. In vitro bioassays showed that boric acid significantly decreases the survivorship of workers regardless of concentration, whereas the morphological data suggested progressive dose-dependent and time-dependent changes in the organs examined, which were evident in the midgut. The midgut is the first organ to be affected, followed by the postpharyngeal gland and Malpighian tubules. This sequence is in agreement with the absorption pathway of this chemical compound in the midgut, its transference to the hemolymph, possibly reaching the postpharyngeal glands, and excretion by the Malpighian tubules. These progressive changes might be due to the cumulative and delayed effect of boric acid. Our findings provide important information for the understanding of the action of boric acid in ant baits in direct and indirect target organs.

Ultrastructural alterations in midgut and Malpighian tubules of Boettcherisca peregrina exposure to cadmium and copper

The effects of Cu and Cd at their at their low concentrations (80microg/g diet) on the morphology and ultrastructure of the midgut and Malpighian tubules of Boettcherisca peregrina larvae were observed by light and transmission electron microscopy. After exposure to both metals, the midgut got darker, shorter, and thicker than in control, and many strumae occurred on the surface of the midgut. Similarly, Malpighian tubules got shorter and thinner. Ultrastructural alterations in the midgut included mitochondrial condensation, swelling, and lysis. The rough endoplasmic reticulum (rER) showed dilation and vesiculation. The microvilli were shortened and disorganized. The stored glycogens increased and many mineral spherites appeared along with lipid droplets decreased. Ultrastructural alterations observed in the Malpighian tubules included rER vesiculation and mitochondria swelling with loss of cristae. Shortened and disordered microvilli, increased numbers of large hydropic vacuoles, and mineral spherites were also observed.