Mosquitofish Research Articles

Side-effects of a neonicotinoid insecticide (actara®) on a non-target larvivorous fish Gambusia affinis: Growth and biomarker responses

Actara® 25 WG belongs to neonicotinoids, which is the most widely used insecticide class for controlling various insect pests in the world. The present study was aimed to assess the potential hazards of this insecticide on the mosquitofish Gambusia affinis following a chronic exposure. The female adults were collected during the reproduction period and exposed to various concentrations (10, 20 and 40 mg.L−1) during 28 days. The effect of actara was investigated on morphometric and selected biomarker measurements. Results showed that the compound was found to affect significantly the condition factor at days 21 and 28 of exposure with the highest concentration. However, the treatment had no effect on hepato-somatic and gonado-somatic indices. Biochemical analyses revealed an increase in glutathione S-transferase activity and carbonylated protein content, and a decrease in acetylcholinesterase activity for the three tested concentrations while the vitellin level was reduced only for the highest concentration. Thus, this product can pose side-effects on this non-target freshwater fish.

Sex-dependent personality in two invasive species of mosquitofish

A key challenge in invasion biology is identifying characteristics that allow some species to be repeatedly successful at invading novel environments. Invasions can often be disproportionately driven by a single sex, with differences in behavioural mechanisms between the sexes potentially underlying sex-biased invasiveness. Here, we took an animal personality approach to study the behaviour of two repeatedly successful congeneric invasive species, the western mosquitofish, Gambusia affinis, and the eastern mosquitofish, Gambusia holbrooki. In each species, we investigated whether males and females shared common personality traits (i.e. behavioural types and behavioural syndromes), with the aim of identifying possible behavioural mechanisms that could help explain why mosquitofish invasions are often characterised by sex-biased founder populations. We found sex-dependent personality, although sex differences varied between species. Male G. affinis were bolder and less social than female G. affinis, whereas we found no behavioural type differences between the sexes in G. holbrooki. We also found a consistent correlation between boldness and exploration in both sexes within G. affinis, but this correlation was weak in G. holbrooki. Finally, exploration was also correlated with sociability in male G. affinis, but not in females. Our results suggest that behavioural tendencies may diverge, both among species and between the sexes, because of adaptation experienced during different invasion pathways. Broadly, identifying the behavioural mechanisms that predict an individual’s ‘invasiveness’ may be difficult to tease apart between species because each invasion is characterised by different abiotic and biotic interactions that likely require different suites of behaviours. Future studies are needed to elucidate whether, in fact, personality variation between the sexes can mediate the occurrence of sex-biased invasions.

Independent Origin of XY and ZW Sex Determination Mechanisms in Mosquitofish Sister Species.

Fish are known for the outstanding variety of their sex determination mechanisms and sex chromosome systems. The western (Gambusia affinis) and eastern mosquitofish (G. holbrooki) are sister species for which different sex determination mechanisms have been described: ZZ/ZW for G. affinis and XX/XY for G. holbrooki Here, we carried out restriction-site associated DNA (RAD-) and pool sequencing (Pool-seq) to characterize the sex chromosomes of both species. We found that the ZW chromosomes of G. affinis females and the XY chromosomes of G. holbrooki males correspond to different linkage groups, and thus evolved independently from separate autosomes. In interspecific hybrids, the Y chromosome is dominant over the W chromosome, and X is dominant over Z. In G. holbrooki, we identified a candidate region for the Y-linked melanic pigmentation locus, a rare male phenotype that constitutes a potentially sexually antagonistic trait and is associated with other such characteristics, e.g., large body size and aggressive behavior. We developed a SNP-based marker in the Y-linked allele of GIPC PDZ domain containing family member 1 (gipc1), which was linked to melanism in all tested G. holbrooki populations. This locus represents an example for a color locus that is located in close proximity to a putative sex determiner, and most likely substantially contributed to the evolution of the Y.

One-pot synthesis of silver nanocomposites from Achyranthes aspera: An eco-friendly larvicide against Aedes aegypti L.

Objective: To formulate silver nanocomposites from Achyranthes aspera leaf extracts and evaluate its larvicidal activity against Aedes aegypti. Methods: The silver nanocomposites were synthesized from Achyranthes aspera leaf extracts. The process was optimized and traced through UV-visible and photon correlation spectroscopy. The larvicidal potential of silver nanocomposites of Achyranthes aspera leaf extracts was assessed against the early fourth instars of Aedes aegypti and three non-target organisms. Furthermore, the most effective and eco-safe nanocomposite was characterized by different biophysical techniques including scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform-infrared spectroscopy (FT-IR). Results: The formulated silver nanocomposites exhibited efficient larvicidal efficacy against Aedes aegypti. Bioassay with silver nanocomposites formulated using different AgNO 3 concentrations (3, 4, and 5 mM) revealed respective LC50 values of 37.570, 6.262 and 1.041 μg/mL; 5.819, 1.412 and 0.489 μg/mL; and 5.519, 1.302 and 0.267 μg/mL after 24, 48 and 72 h. The silver nanocomposites with 4 mM AgNO3 were selected for characterization. SEM and TEM analysis revealed spherical, poly-dispersed structure with varied diameters of 1-25 nm. The XRD analysis established the crystalline and face-centred-cubic structure of silver nanocomposites with the maximum peak at a 2θ value of 37.42°. The EDX pattern showed the presence of Ag, O and C in the nanocomposites in their order of weight%. The FT-IR displayed visibly distinct peaks in different ranges demonstrating the intricacy of silver nanocomposites. In addition, the lethal concentrations of silver nanocomposites of Achyranthes aspera leaf extracts against Aedes aegypti larvae were non-toxic to non-target organisms including Gambusia affinis, Daphnia magna and Moina macrocopa. Conclusions: Silver nanocomposites synthesized with leaf extract of Achyranthes aspera provide a cost-effective and eco-safe alternative to conventional insecticides, and can be utilized as a potent mosquito nano-larvicide.

Susceptibility of betanodavirus in a newly established vertebra-derived cell line from Mosquitofish (Gambusia affinis).

In the present study, a new cell line from the vertebra of mosquitofish Gambusia affinis was successfully established and characterized. The cell line is named as bone Gambusia affinis (BGA) and subcultured for more than 55 passages in Leibovitz's/L15 medium supplemented with 15% FBS at 28°C. The cell line has a modal chromosome number of 48. Molecular characterization of the partial sequence of the coi gene confirmed the origin of the BGA cell line from mosquitofish. These cells exhibited epithelial morphology confirmed by the cytokeratin marker. The BGA cells showed mineralization of their extracellular matrix when stained with alizarin red and von Kossa stain. BGA cells were found to be susceptible to RGNNV and SJNNV strains of betanodavirus (NNV) showing cytopathic effect with multiple vacuolations in the cells. The RT-PCR confirmed the betanodavirus infections in BGA cells. The SEM micrograph showed the morphological changes observed in the cell during virus infection. The in vivo challenge experiment also showed the viral replicating efficiency in the Gambusia affinis with increasing viral titre. Thus, our present results show that the BGA cell line is a useful tool for isolating betanodavirus and could be used to investigate bone cell differentiation and extracellular matrix mineralization.

The effect of cadmium exposure on the cytoskeleton and morphology of the gill chloride cells in juvenile mosquito fish (Gambusia affinis)

One of the wide spread aquatic organisms in the rivers of Indonesia is the mosquito fish (Gambusia affinis (Baird and Girard, 1853)). Mosquito fish are invasive species that can adapt to environmental changes, also they act as bioindicator species for polluted environments. The study aims to determine the effects of the exposure to cadmium on the cytoskeleton and morphology of the gill’s Chloride Cells (CCs) in the mosquito fish. In cadmium treated mosquito fish (0.03 mg/L for 28 days), the immuno-fluorescent light microscope showed strong absorption of actin stain and strong primary MT antibody uptake in CC and apical epithelia. Scanning electron microscopy observations showed a change in microfilament organized at the CC's apex, with the appearance of some actin filament aggregates. Higher cadmium concentrations (0.03 and 0.015 mg/L) did not alter such reorganization. Microtubules weren’t significantly affected by similar exposures. SEM analysis showed that cadmium exposure induced a significant increase in CC's surface area. After 28 days, the density of CC also increased. It was observed that there is an increase of CC's surface area, although the CC density didn’t increase significantly. The results of this study confirmed the cytotoxic effects of cadmium on mosquito fish.

Life in a contaminant milieu: PPCP mixtures generate unpredictable outcomes across trophic levels and life stages

AbstractNearly all aquatic ecosystems are affected by sublethal levels of anthropogenic chemical contamination, but other agents of large‐scale anthropogenic disruption of ecosystems have received more attention. Consequently, ecologists do not fully appreciate how sublethal contaminant exposure affects ecosystems. Sublethal contaminants can affect ecological systems directly via their impacts on an organism's fitness or indirectly by changing the strengths of species interactions. This study investigated how an emerging class of contaminants—pharmaceuticals and personal care products (PPCPs)—influences food webs by affecting the biology of organisms and by interfering with predator–prey interactions. Specifically, we investigated how three common PPCPs—caffeine, DEET (N, N‐diethyl‐meta‐toluamide), and triclosan—affect the strength of the interaction between a common mosquito predator (i.e., mosquito fish) and mosquito larvae as well as how these PPCPS affect mosquito survival, life history traits, and oviposition site choices. We found that all three PPCPs, individually and combined as a mixture, reduced predator consumption rates. Relative to a contaminant‐free control, the presence of predator cues reduced mosquito oviposition and larval abundance for all PPCP treatments except for DEET. Predator cues reduced mosquito adult emergence across PPCP treatments; however, mosquitoes that were exposed to caffeine did not emerge as adults even in the absence of predator cues. This study shows that the effects of PPCPs are diverse and can interact with mosquitoes and their predators in ways that cannot be predicted by their individual effects. In a contaminated world, ecologists need to better understand how sublethal concentrations of ubiquitous, biologically active pollutants might challenge what we think we know about how ecological systems function.

Domperidone treatment advances onset of puberty in the viviparous mosquitofish Gambusia affinis

BackgroundAlthough dopamine (DA) exerts modulatory effect on reproduction in the majority of fishes, its role is not clearly understood in viviparous species. The aim of this investigation was to determine the influence of DA antagonist domperidone (DOM) on puberty in the viviparous species Gambusia affinis.ResultsTreatment of 1.5 or 4 mg DOM to 25 days post-hatching (DPH) juveniles for a period of 35 days resulted in dense aggregations of gonadotropin-releasing hormone (GnRH)-immunoreactive fibres in the proximal pars distalis (PPD) region of the pituitary gland in contrast to faintly seen fibres in treatment controls. In the ovary, the follicles belonging to stages I–IV did not differ significantly among different experimental groups. However, stage V (vitellogenic) follicles were completely absent in treatment controls in contrast to their presence in 1.5 or 4 mg DOM-treated fish. Besides, the diameter of stage V follicles was significantly higher in 1.5 mg DOM-treated fish compared with 4 mg DOM-treated fish.ConclusionsThe results suggest that DOM treatment triggers the follicular development and promotes the early onset of puberty, possibly by attenuating the dopaminergic inhibition on GnRH fibres, for the first time in a viviparous species.

Development and characterization of a skin cell line (SGA) from the mosquitofish Gambusia affinis and its susceptibility to fish Betanodavirus

A new continuous cell line designated as SGA has been developed from the skin tissue of the freshwater mosquitofish Gambusia affinis. The cell line grew well in Leibovitz's L-15 medium supplemented with 15% fetal bovine serum at 28 °C. Immunophenotyping of the cell line showed the epithelial nature of the cells. Chromosome number analysis showed that SGA cells have a modal diploid chromosome number of 48. Replication of the two different strains of betanodavirus (RGNNV and SJNNV) in SGA cell line showed the maximum virus titre of 108.82 TCID50 mL−1 for RGNNV and 107.2 TCID50 mL−1 for SJNNV. The cytopathic effect in the cell line was observed at 3 days post-infection (dpi) and multiple vacuolations were observed at 7 dpi. Further, DsRed2 plasmid was efficiently delivered into SGA cell line and was found that these cells were transfectable and can be used for assessing gene promoter activity. In vivo challenge experiments using the RGNNV infected cell culture supernatant showed signs of the disease in healthy mosquitofish with mortality commencing from 15 dpi. The above results suggest that the cell line is permissive for propagating betanodavirus and also could be an essential tool for studying the molecular pathogenesis of betanodavirus infection.

Knowledge, Attitude, and Practices Regarding Dengue Fever among Pediatric and Adult In-Patients in Metro Manila, Philippines.

Background: Knowledge, attitude, and practice (KAP) of in-patients with dengue fever (DF) through hospital-based surveillance has not been done. This study aimed to assess and compare the KAP, identify its predictors, correlation, and protective factors among pediatric and adult patients with DF and community-based controls to structure proactive community-wide DF prevention and control programs. Methods: This case-control study involved clinically or serologically confirmed patients (pediatrics n = 233; adults n = 17) with DF admitted in three public hospitals and community-based controls in Metro Manila, Philippines. A pretested structured KAP questionnaire was administered to participants to assess their KAP. Results: Pediatric and adult patients had significantly lower mean scores in the practice (p < 0.001) domain compared with the pediatric and adult controls. Being in senior high school, having had days in hospital, and rash were predictors of KAP among pediatric patients. Knowledge and attitude of patients with DF did not correlate with their practices against DF. Use of mosquito-eating fish, screen windows, and dengue vaccine were protective factors against DF. Conclusion: The study highlights the importance of behavioral change for knowledge and attitude to have significant effect to practices against DF. Thus, we recommend two comprehensive health programs, Communication for Behavioral Impact (COMBI) and Health Belief Model (HBM).

Geographical and temporal variation of multiple paternity in invasive mosquitofish (Gambusia holbrooki, Gambusia affinis).

Multiple paternity (MP) increases offspring's genetic variability, which could be linked to invasive species' evolvability in novel distribution ranges. Shifts in MP can be adaptive, with greater MP in harsher/colder environments or towards the end of the reproductive season, but climate could also affect MP indirectly via its effect on reproductive life histories. We tested these hypotheses by genotyping N=2,903 offspring from N=306 broods of two closely related livebearing fishes, Gambusia holbrooki and Gambusia affinis. We sampled pregnant females across latitudinal gradients in their invasive ranges in Europe and China, and found more sires per brood and a greater reproductive skew towards northern sampling sites. Moreover, examining monthly sampling from two G. affinis populations, we found MP rates to vary across the reproductive season in a northern Chinese, but not in a southern Chinese population. While our results confirm an increase of MP in harsher/more unpredictable environments, path analysis indicated that, in both cases, the effects of climate are likely to be indirect, mediated by altered life histories. In both species, which rank amongst the 100 most invasive species worldwide, higher MP at the northern edge of their distribution probably increases their invasive potential and favours range expansions, especially in light of the predicted temperature increases due to global climate changes.

Oviposition Behavior of Culex tarsalis (Diptera: Culicidae) Responding to Semiochemicals Associated with the Western Mosquitofish, Gambusia affinis (Cyprinodontiformes: Poecilliidae).

Considerable previous research has focused on predator-associated semiochemicals and how they affect mosquito oviposition behavior. However, most of this work has been done without taking into consideration either the natural density of the predators or how other semiochemicals in aquatic environments might affect the responses of gravid mosquitoes. The influence of mosquitofish density, source water (tap vs pond), presence of freshly laid egg rafts, and removal of a putative source of semiochemicals (bacteria) on oviposition by Culex tarsalis Coquillett (Diptera: Culicidae) was studied in laboratory bioassays. Culex tarsalis females were deterred from laying egg rafts on water that contained semiochemicals associated with Gambusia affinis (Baird & Girard), but this deterrence was not strongly associated with the density of fish used to condition aged tap water. The number of egg rafts laid onto Gambusia-exudate water made with either tap water (density < 1 fish per liter) or pond water was typically ≥ 50% of that onto water that did not house mosquitofish. Gravid mosquitoes tested individually did not reduce oviposition onto Gambusia-exudate water as compared to controls. Likewise, oviposition by females with ablated wings did not differ significantly between Gambusia-exudate water and controls. Oviposition onto filter-sterilized Gambusia-exudate water was reduced relative to unfiltered water, suggesting that semiochemicals deterring egg-laying were still present after bacteria were removed. Taken together, these findings suggest that the responses of gravid Cx. tarsalis to chemicals from habitats containing mosquitofish are complex and the origin of the semiochemicals present in the Gambusia-exudate water needs to be elucidated.

Domperidone treatment attenuates stress-induced suppression of reproduction in viviparous mosquitofish Gambusia affinis.

The aim of this study was to determine the effect of stress on reproduction and the possible involvement of dopaminergic systems in the reproductive stress response in the mosquitofish Gambusia affinis. Exposure of fish to aquaculture stressors (four 10 min episodes of stress, each corresponding to a different stressor such as handling, chasing, frequent netting and low water levels), for a period of 30 days caused reduction in the mean numbers of stage I-IV follicles associated with lower number of pregnant females and embryos in most of the developmental stages compared with experimental controls. Besides, increase in the intensity of labelling and the per cent area of tyrosine hydroxylase (TH; a rate-limiting enzyme in the biosynthetic pathway of catecholamines)- immunoreactive (ir) neurons was observed in the preoptic area (POA) and the nucleus preopticus (NPO) regions of the brain concomitant with reduction in the labelling of gonadotropin releasing hormone-immunoreactive (GnRH-ir) fibres in the proximal pars distalis (PPD) of the pituitary gland in stressed fish compared with experimental controls. Treatment of domperidone (DOM) caused an increase in the number of stage II and V follicles and promoted pregnancy rate concomitant with an increase in the number of embryos at various developmental stages compared with those of experimental controls. Similar treatment to stressed fish caused an increase in the number of stages I-V follicles compared with those in stress alone group. The GnRH fibres showed increased immunolabelling in stress + DOM treated fish compared with stress alone fish. On the other hand, TH-immunoreactivity in the POA and the NPO regions was reduced in stress + DOM treated fish compared with stress-alone group. These results suggest that stress inhibits follicular development and subsequent hatching success through the suppression of GnRH and that the inhibition appears to be mediated through dopamine, for the first time in a viviparous fish.

Molecular and Histopathological Data on Levisunguis subaequalis Curran, Overstreet, Collins &amp; Benz, 2014 (Pentastomida: Eupentastomida: Porocephalida: Porocephaloidea: Sebekidae: Sebekinae) from Gambusia affinis in Alabama, USA

Levisunguis subaequalis Curran, Overstreet, Collins & Benz, 2014 , was recently described from the lungs of the definitive hosts, softshell turtles, Apalone ferox (Schneider, 1783), and Apalone spinifera aspera (Agassiz, 1857) as well as the viscera of an intermediate host, the western mosquitofish, Gambusia affinis (Baird and Girard, 1853). However, the original account lacked molecular data. Furthermore, histological examination of infected host tissues in the original account of L. subaequalis did not reveal any pathological changes in the intermediate host. The present work provides a robust morphological description of the nymph and novel molecular data from the 18S and 28S ribosomal gene regions and the cytochrome c oxidase subunit 1 (COI) mitochondrial gene. Phylogenetic analyses using Bayesian inference and maximum likelihood analysis with concatenated sequence data from these 3 regions, as well as each region individually, placed the turtle pentastomid L. subaequalis as a sister clade to the crocodilian pentastomids of the genus Sebekia Sambon, 1922. While only concatenated phylogenetic analyses agreed with the currently accepted classification of the Eupentastomida and phylogenetic signal assessment indicated that the concatenated data set yielded the most phylogenetic signal, data from more taxa are still needed for robust phylogenetic inferences to be made. The intensity of infection ranged from 2 to 171 nymphs per fish, compared with the highest previously reported intensity of 6. These high-intensity infections with L. subaequalis were characterized by the nymphs occupying 5-50% of the coelomic cavity of G. affinis. However, despite this heavy parasite infection, fish exhibited minimal pathology. Observed pathology was characterized by compression or effacement of organs adjacent to the nymphs, particularly liver, swim bladder, and intestines, as well as the formation of granulomas around shed pentastomid cuticles. Nonetheless, the morphological and molecular data provided in the present work will bolster future efforts to identify this pentastomid in other hosts where pathology may be present in addition to aiding in the advancement of the field of molecular pentastomid systematics.

Intermediate turbidity elicits the greatest antipredator response and generates repeatable behaviour in mosquitofish

Increased turbidity, a common human-induced aquatic disturbance, can potentially have major impacts on predator–prey interactions via effects on key foraging and antipredator behaviours, on the repeatability of these behaviours (i.e. on animal personalities) and on behavioural syndromes (correlations among behaviours). Here, we repeatedly assayed individual western mosquitofish, Gambusia affinis, across a range of turbidity levels (low, intermediate, high) to test the degree to which a suite of behaviours (activity, exploration, sociality, responses to olfactory predator cues) scaled with increasing turbidity. In particular, we tested the a priori hypothesis, based on previous work, that fish show stronger behavioural repeatability and behavioural correlations when perceived predation risk is high. While individuals in all treatments responded to predator cues by reducing activity and exploration, those assayed in intermediate turbidity exhibited the strongest antipredator responses. Consistent with our prediction that repeatability should be greatest in high risk, significant behavioural repeatability was only detected in antipredator behaviours at intermediate turbidity. Significant correlations among behavioural traits were detected in all turbidity treatments but primarily under threat of predation – not when predator cues were absent (with one exception). This study demonstrates that levels of human-induced environmental change may interact with predation risk to shape both mean behavioural responses as well as patterns of behavioural correlations within and among individuals.

A comparison of the establishment success, response to competition, and community impact of invasive and non-invasive Gambusia species

How an invader responds to the novel biotic elements of a new community will affect its ability to invade. Species that are able to cope well with novel competitors might be expected to achieve greater establishment success. We compared the population-level responses of two mosquitofish species, the widespread invader Gambusia affinis and non-invasive G. geiseri to competition from each other and a non-invasive competitor. We simulated the invasion of a simplified pond community by introducing different combinations of the Gambusia spp. into communities already inhabited by a novel competitor, the red shiner Cyprenella lutrensis. We measured the effect of competition on establishment success by comparing population abundances achieved by each Gambusia species in all treatments, and examined whether the invasive and non-invasive Gambusia differed in their community impact by comparing their effects on the abundances of pond fauna. We also used N and C stable isotope analysis to compare their trophic roles. Both novel and intrageneric competition negatively affected both Gambusia spp.’s abundances, but the invasive G. affinis managed to remain more abundant than G. geiseri regardless of competition treatment. Stable isotope analysis revealed the Gambusia spp. to have similar trophic placement and showed competition to cause significant trophic shifts only in G. geiseri. A cascading effect (reduced phytoplankton abundances) was detected only when G. affinis was present. These results suggest that a higher vulnerability to novel competition along with life history traits contributes to the limited spread of G. geiseri in comparison to the widespread G. affinis.

Eco-evolutionary feedbacks link prey adaptation to predator performance.

Eco-evolutionary feedbacks may determine the outcome of predator-prey interactions in nature, but little work has been done to quantify the feedback effect of short-term prey adaptation on predator performance. We tested the effects of prey availability and recent (less than 100 years) prey adaptation on the feeding and growth rate of largemouth bass (Micropterus salmoides), foraging on western mosquitofish (Gambusia affinis). Field surveys showed higher densities and larger average body sizes of mosquitofish in recently introduced populations without bass. Over a six-week mesocosm experiment, bass were presented with either a high or low availability of mosquitofish prey from recently established populations either naive or experienced with bass. Naive mosquitofish were larger, less cryptic and more vulnerable to bass predation compared to their experienced counterparts. Bass consumed more naive prey, grew more quickly with naive prey, and grew more quickly per unit biomass of naive prey consumed. The effect of mosquitofish history with the bass on bass growth was similar in magnitude to the effect of mosquitofish availability. In showing that recently derived predation-related prey phenotypes strongly affect predator performance, this study supports the presence of reciprocal predator-prey trait feedbacks in nature.

Invasive aquatic plant (Alternanthera philoxeroides) facilitates the invasion of western Mosquitofish (Gambusia affinis) in Yangtze River, China

We investigated the seasonal habitat selection of Mosquitofish to increase our understanding of the ecology and invasiveness of this species. Sampling was conducted during the reproductive and non-reproductive season of Mosquitofish in four habitat types: Alternanthera philoxeroides habitat, Typha angustifolia habitat, Paspalum distichum habitat, and no vegetation habitat. Mosquitofish catch per unit effort was significantly lower in Typha habitat than in the other three habitats during the reproductive season. T. angustifolia can exude allelopathic chemicals and have the potential to negatively influence western Mosquitofish abundance. In the non-reproductive season, catch per unit effort of Mosquitofish were significantly higher in Alternanthera habitat than in the other three habitats. These results suggest that mats of A. philoxeroides provided an insulating layer for Mosquitofish overwintering. Therefore, Mosquitofish could expand its range further north in China as A. philoxeroides spreads northward with climate change. We suggest that an effective way of controlling western Mosquitofish is through eradication of the invasive macrophyte (A. philoxeroides) stands while retaining and restoring more native emergent macrophyte (T. angustifolia) stands; this strategy could limit overwintering habitat for western Mosquitofish and may draw them into open water habitats where they can be more easily removed.

Molecular Detection of Mosquitofish (Gambusia affinis) in the South-western Region of Bangladesh

Molecular Detection of Mosquitofish (Gambusia affinis) in the South-western Region of Bangladesh

Pathological Study of Experimental Glyphosate Toxicity in Mosquito Fish Gambusia affinis

The present study deals with the effect of herbicide glyphosate on mosquito fish Gambusia affinis. Fish were exposed to different concentrations of the mentioned pesticide, behavioral and histological effects of various concentrations of glyphosate on mosquito fish Gambusia affinis in the acute exposure (96) hours were investigated.There were behavioral changes on the exposed fishes represented by nervous symptoms, loss of equilibrium, increas in respiration rate, opening of mouth and histological changes were determined in gills after acute exposed such as hyperplasia, hemorrhage, aneurysms, separation of epithelial layer, clubbing with sickle lamellae, hypertrophy, destroyed and fusion of secondary lamellae.The liver tissues were showed that hypertrophy of nucleus and necrosis and degeneration and swelling of cells, increasing of size and bleeding and congestion of blood vessels and bilirubin pigment diffusing around bile duct, in kidney tissues there were necrosis and degeneration of epithelial cells of tubules, increasing of size of Bowman᾿ s capsule, congestion and atrophy and disappear of glomerulus, separation of tubules, increasing of size and congestion of blood vessels, bleeding between tubules and bilirubin pigment diffusing around blood vessels.