Mosquitofish Research Articles

Elucidating the status of malaria in Andaman and Nicobar Islands post-millennium 2000.

Malaria is a major vector-borne disease in the Indian sub-continent and has been pestering Andaman and Nicobar islands (ANI's) as well since British colonial times. A retrospective data mining technique has been adhered to assess the status of malaria for nineteen years from 2000 to 2019 in ANI's. The altered environment due to 2004 tsunami had increased malaria incidence significantly during (2005-2010). The Nicobar district recorded high incidence of malaria while the least in the north and middle Andaman district. Comparative high incidence of malaria was documented due to Plasmodium falciparum than Plasmodium vivax in the Nicobar district between 2005 and 2009. The declining trend of malaria-positive cases in ANI's was observed post 2010, articulating various initiatives taken by the local Andaman and Nicobar administration to curb this vector-borne disease. The initiatives were like (1) large-scale release of larvivorous fish, Gambusia affinis in the transient water pools, (2) outdoor application of DDT, (3) indoor application of Pyrethrum, (4) malaria awareness drive that led to the curbing of the proliferation not only the malaria vector but also other potential mosquito vector species as well, and (5) implementation of revised drug policy.

Are superficial neuromasts proprioceptors underlying fast copulatory behavior?

In male Poeciliid fishes, the modified anal fin (i.e., gonopodium) and its axial and appendicular support are repositioned within the axial skeleton, creating a novel sexually dimorphic ano-urogenital region. During copulation, the relative location of the gonopodium is crucial for successful insemination. Therefore, the repositioning of these structures and organ relied on the reorganization of the efferent circuitry that controls spinal motor neurons innervating appendicular muscles critical for the movement of the gonopodium, including the fast and synchronous torque-trust motion during insemination attempts. Copulation occurs when a male positions himself largely outside a female’s field of view, circumducts his gonopodium, and performs a rapid, complex maneuver to properly contact the female urogenital sinus with the distal tip of the gonopodium and transfers sperm. Although understanding of the efferent circuitry has significantly increased in the last 24 years, nothing is known about the cutaneous receptors involved in gonopodium movement, or how the afferent signals are processed to determine the location of this organ during copulation. Using Western mosquitofish, Gambusia affinis, as our model, we attempt to fill this gap in knowledge. Preliminary data showed cutaneous nerves and sensory neurons innervating superficial neuromasts surrounding the base of adult male gonopodium; those cutaneous nerves projected ventrally from the spinal cord through the 14th dorsal root ganglion and its corresponding ventral root towards the base and fin rays of the gonopodium. We asked what role the cutaneous superficial neuromasts play in controlling the positioning and timing of the gonopodium’s fast and synchronous movements for effective sperm transfer. First, we found a greater number of superficial neuromasts surrounding the base of the male’s gonopodium compared to the base of the female’s anal fin. Second, we systemically removed superficial neuromasts surrounding the gonopodium base and observed significant impairment of the positioning and timing of gonopodial movements. Our findings provide a first step to supporting the following hypothesis: during radical reorganization of the Poeciliid body plan, superficial neuromasts have been partially co-opted as proprioceptors that allow the gonopodium to control precise positioning and timing during copulatory attempts.

Spatio-temporal patterns of occurrence of microplastics in the freshwater fish Gambusia affinis from the Brantas River, Indonesia

The first investigation of microplastics in G. affinis from the Brantas River was carried out in this study. Microplastics were found at higher concentrations in gambusia fish captured downstream (209.18 ± 48.85 particles/gram) than upstream (24.44 ± 0.14 particles/gram). Microplastic particle concentrations in G. affinis have a positive linear relationship with fish length. The fiber was the most prominent shape at Sites 1 and 2, whereas the fragment was dominant at Sites 3 and 4. With a value of 45–48%, black dominates the entire site, followed by blue (29–38%), transparent colors (7–11%), red (2–4%), purple (1–3%), and other colors (5–7%). Microplastics measuring <0.1 mm are commonly found in fish bodies. Cyclohexylmethyl octyl ester (phthalic acid) is the most abundant component found in microplastics, accounting for 30.11% of the total. This study provides evidence that G. affinis can be used to monitor the presence of microplastic pollution in the Brantas River but further studies are needed regarding the effects of microplastics and their health hazards on fish.

Programmatic review of the mosquito control methods used in the highly industrialized rice agroecosystems of Sacramento and Yolo Counties, California

In the Sacramento Valley (California, USA), rice (Oryza sativa L.) fields are an economically important crop and productive habitats for the mosquito species Culex tarsalis and Anopheles freeborni. Since 2010, approximately 150 km2 of conventional and 16 km2 of organic rice have been grown in Sacramento and Yolo Counties. These fields are often within mosquito flight-range of both rural towns and urban centers. Culex tarsalis are highly competent vectors of West Nile virus, and An. freeborni are aggressive, mammalophagic, nuisance biters. The Sacramento–Yolo Mosquito and Vector Control District provides mosquito control for the two counties in its jurisdiction. The principles of Integrated Pest Management are used to control mosquitoes in rice growing areas, relying upon a range of surveillance and control interventions. Larvae are controlled by limiting habitats that enable development of immature mosquitoes while balancing agricultural and wildlife needs, applying larvicides, and the use of Gambusia affinis (mosquitofish). Adult mosquitoes are controlled by ultra-low volume pesticide applications. The program was assessed for larval and adult mosquito control efficacy and areas of programmatic improvement identified. Because rice fields are productive habitats for mosquitoes, complete elimination of the habitat is not a feasible goal, thus efforts are aimed at interrupting disease transmission and reducing the number of mosquitoes that traverse into populated areas.

Toxicological effects of polystyrene nanoplastics and perfluorooctanoic acid to Gambusia affinis

Plastic pollution has attracted huge attention from public and scientific community in recent years. In the environment, nanoplastics (NPs, <100 nm) can interact with persistent organic pollutants (POPs) such as perfluorooctanoic acid (PFOA) and may exacerbate associated toxic impacts. The present study aims to explore the single and combined ecotoxicological effects of PFOA and polystyrene nanoplastics (PS-NPs, 80 nm) on the PI3K/AKT3 signaling pathway using a freshwater fish model Gambusia affinis. Fish were exposed individually to PS-NPs (200 μg/L) and PFOA (50, 500, 5000 μg/L) and their chemical mixtures for 96 h. Our results showed that the co-exposure significantly altered the mRNA relative expression of PI3K, AKT3, IKKβ and IL-1β, compared to corresponding single exposure and control groups, indicating that the PFOA-NP co-exposure can activate the PI3K/AKT3 signaling pathway. The bioinformatic analyses showed that AKT3 had more probes and exhibited a significantly sensitive correlation with DNA methylation, compared to other genes (PIK3CA, IKBKB, and IL1B). Further, the mRNA expressions of PIK3CA, AKT3, and IKBKB had a significant correlation with copy number variation (CNV) in human liver hepatocellular carcinoma (LIHC). And PIK3CA had the highest mutation rate among other genes of interest for LIHC. Moreover, AKT3 showed a relatively lower expression in TAM and CAF cells, compared to PIK3CA, IKBKB, and IL1B. Besides, hsa-mir-155-5p was closely correlated with AKT3, PIK3CA, IKBKB, and IL1B. In summary, these results provide evidence that NPs could enhance the carcinogenic effects of POPs on aquatic organisms and highlight possible targets of LIHC induced by PFOA-NP co-exposure.

Essential oil of Origanum vulgare, its nanoemulsion and bioactive monoterpenes as eco-friendly novel green pesticides for controlling Aedes aegypti, the common vector of Dengue virus

ABSTRACT Essential oil (EO) of Origanum vulgare L. was hydrodistilled and analysed using gas chromatography–flame ionization detection and gas chromatography–mass spectrometry. The monoterpenes, carvacrol (61.2%), γ-terpinene (9.6%), thymol (8.3%), and p-cymene (5.7%) were identified. Oil-in-water nanoemulsion was prepared and characterized from the EO through a green procedure. Botanicals had a remarkable mosquitocidal and effectively inhibited acetylcholinesterase activity of Aedes aegypti. The nanoemulsion at 40 µg/ml caused 100% adult and larval mortality after 12 h. At 80 µg/ml, percentage mortality caused by EO products ranged between 55.11-100% for larvae, and 63.0 -100%. for adults After 24 h exposure, LC50's ranged between 13.2 and 75.7 µg/ml against larvae, and between 10.1 and 36.0 µg/ml against adults. The lethal time (LT50) decreased with nanoemulsion, EO and carvacrol. Test products were safe towards the non-target aquatic species, Gambusia affinis and Diplonychus indicus. Results recommend test botanicals as natural alternatives to control Ae. aegypti.

Environmental Quality Identification of Wangi the River Polluted by Waste Based on the Environmental Pollution Index

High amount of wastewater release to Wangi riverflow, especially industrial wastewater, can potentially cause pollution. Pollution in river has been occurred since 2015. The aim of this study was to identify the environmental quality of contaminated Wangi River and determine the pollution index. This study was performed through a survey method, and river water sampling was carried out around the Wangi riverflow, Beujeng-Beji, Pasuruan District. Sampling was conducted in three locations, namely industrial, residential, and agricultural areas on different months (June 2020 - July 2021). This study was also conducted to analyze the heavy metal content of Pb, Hg and Cd in Wangi river biota around the watershed, namely mosquito fish (Gambusia affinis). The pollutant identification result was based onthree study areas, namely study area I (factory/industrial waste), study area II (residential waste) and study area III (agricultural waste). Heavy metal contamination occurred in Wangi River hhe as the potential to produce waste containing Pb, Cd and Hg. The average levels of Pb, Cd and Hg in the water were 0.031 ppm, 0.019 and 0.009 ppm, respectively. These values exceeded the acceptable quality standard. The result of data analysis based on the pollution index (PI) and average number of pollution indexes (PIaverage) in the Wangi river (at study areas I, II and III) was 5.503, which means thatthe condition of the Wangi river is classified as a “moderately-polluted” river. The authority is expected to develop a further policy for Wangi riverflow preservation program.

The effect of pregnancy on metabolic scaling and population energy demand in the viviparous fish Gambusia affinis.

Metabolism is a fundamental attribute of all organisms that influences how species affect and are affected by their natural environment. Differences between sexes in ectothermic species may substantially alter metabolic scaling patterns, particularly in viviparous or live-bearing species where females must support their basal metabolic costs and that of their embryos. Indeed, if pregnancy is associated with marked increases in metabolic demand and alters scaling patterns between sexes, this could in turn interact with natural sex ratio variation in nature to affect population-level energy demand. Here, we aimed to understand how sex and pregnancy influence metabolic scaling and how differences between sexes affect energy demand in Gambusia affinis (Western mosquitofish). Using the same method, we measured routine metabolic rate in the field on reproductively active fish and in the laboratory on virgin fish. Our data suggest that changes in energy expenditure related to pregnancy may lead to steeper scaling coefficients in females (b=0.750) compared to males (b=0.595). In contrast, virgin females and males had similar scaling coefficients, suggesting negligible sex differences in metabolic costs in reproductively inactive fish. Further, our data suggest that incorporating sex differences in allometric scaling may alter population-level energy demand by as much as 20-28%, with the most pronounced changes apparent in male-biased populations due to the lower scaling coefficient of males. Overall, our data suggest that differences in energy investment in reproduction between sexes driven by pregnancy may alter allometric scaling and population-level energy demand.

Increasing salinization of freshwater limits invasiveness of a live-bearing fish: Insights from behavioral and life-history traits

Biological invasions and continued salinization of freshwater are two global issues with largely serious ecological consequences. Increasing salinity in freshwater systems, as an environmental stressor, may negatively affect normal life activities in fish. It has been documented that salinity limits the invasive success of alien species by mediating physiological and life-history performances, however, there are few studies on how salinity affects its invasive process via altered behaviors. Using wild-caught invasive western mosquitofish (Gambusia affinis) as animal model, in this study, we asked whether gradual increasing salinity affects behaviors (personality and mate choice decision here), life-history traits, as well as the correlation between them by exposing G. affinis to three levels salinity (freshwater, 10 and 20‰). Results showed that, with increased salinity, male tended to be shyer, less active, less sociable, and reduced desire to mate, and female tended to be shyer, less active and lost preferences for the larger male. Furthermore, across salinity treatments, male exhibited reduced body fat content and rising reproduction allocation, however, pregnant female revealed diametrically opposed trends. In addition, the correlation between life-history traits and behaviors was only identified in pregnant female. It seems that either salinity or life-history traits directly affects mosquitofish behaviors. In summary, our results partially emphasize the harmful consequences of salinity on both life-history traits and behavioral performances. These findings provide a novel perspective on how salinity potentially affect fish fitness via altering personalities, mate choice decisions, as well as body condition, and hence supports the idea that salinity could affect the spread of invasive mosquitofish.

Eco-biological Study of the Mosquitofish Gambusia affinis from Oubeira lake

Gambusia was studied in Oubeira lake in spring 2016. A total of 100 specimens were collected in the lake. The sex ratio was F:M = 5.12: 1. The length-weight relationship was estimated for the population, with Wt = 0.0197Lt2.4451. The condition factor was calculated C=1±0.2 (for population) and a significant difference was observed between males and females. For 100 examined stomachs, the diet mainly consists of algae (N=54.96%, Pi= 166%, O=91%), followed by the mosquito larvae (N=21.52%, Pi= 65%, O=49%), detritus (N=19.2%, Pi= 58%, O=46%) and arthropods (N=4.3%, Pi= 13%, O=13%). For mosquitoes, two genus were recorded: Culiseta and Culex with 4 species: Culex pipiens, Culex theileri, Culex laticinctus and Culex antennatus. The culture experiments confirmed the important predation on mosquito larvae was observed with feeding intensity for females and males of 86 ± 12.28 % and 92 ± 8 % for the Culex larvae and 91 ± 7 and 93.66 ± 5.68 for the Culiseta larvae, respectively. No significant difference was observed between the sexes or for mosquito larvae. Our data support the idea that the introduction of mosquitofish has both negative and positive effects since this fish feeds on the most abundant food and not only on mosquitoes.

Assessment of biochemical biomarkers of mosquitofish (Gambusia affinis (Baird et Girard, 1853)) on exposure to the insecticide cypermethrin

ABSTRACT Cypermethrin (CYP) is a synthetic pyrethroid insecticide, used in agriculture, and one of the most common contaminants in freshwater aquatic systems. This paper reports an evaluation of the toxicity of CYP in the mosquitofish, exposed to two concentrations (0.2 ng/L and 6.25 ng/L). The result revealed a significant modulation in the activity of antioxidants enzymes, superoxide dismutase, catalase and decreased acetylcholinesterase after 7 days. Hydrogen peroxide (H2O2) and malondialdehyde levels remained elevated throughout the exposure duration. CYP causes gills and liver oxidative stress, modifying the antioxidant enzymes. Principal component analysis highlighted relationship between biomarkers in functional response. These findings suggest that exposure to CYP can lead to various antioxidant processes in the fish gills and liver.

Prevalence of parasitic infections in fish from markets in Zhenjiang City from 2017 to 2020

To investigate the prevalence of parasitic infections in freshwater fish and marine fish from markets in Zhenjiang City, so as to provide the evidene for formulating targeted control measures. Freshwater fish and marine fish were collected from farmers' markets and supermarkets in Zhenjiang City using a random sampling method. The metacercaria and larvae of parasites were detected using microscopy and the direct dissection method. The prevalence of parasitic infections was analyzed in freshwater fish and marine fish. The overall prevalence of parasite infections was 11.21% (208/1 856) in the 1 856 fish (34 species) detected from 2017 to 2020, and the prevalence was 9.81% (117/1 193) in freshwater fish and 13.73% (91/663) in marine fish. Among the 1 193 freshwater fish (23 species), high prevalence of parasitic infections was detected in Gambusia affinis (43.33%), coarse fish (32.93%) and Hemiculter leucisclus (20.20%), and there was no significant difference in the prevalence of parasitic infections among different species of freshwater fish (χ2 = 105.66, P < 0.05). Clonorchis sinensis, Metorchis orientalis and other parasite species were detected in freshwater fish, with detection rates of 0.59% (7/1 193), 1.93% (23/1 193) and 7.29% (87/1 193), respectively, and there was a significant difference in the detection of C. sinensis and M. orientalis in freshwater fish (χ2 = 8.64, P < 0.05). The prevalence and intensity of larval Anisakis infections were 13.73% (91/663) in marine fish and 3.43 parasites per fish. High prevalence of Anisakis infections was seen in little yellow croaker fish (30.28%) and hairtail (27.50%), and there was a significant difference in the prevalence of parasitic infections in different species of marine fish (χ2 = 12.93, P < 0.05). Parasitic infections are prevalent in freshwater fish and marine fish from markets of Zhenjiang City, and there is a risk of parasitic infections following consumption of raw or under-cooked freshwater fish and marine fish.

Multigenerational exposure to increased temperature reduces metabolic rate but increases boldness in Gambusia affinis.

Acute exposure to warming temperatures increases minimum energetic requirements in ectotherms. However, over and within multiple generations, increased temperatures may cause plastic and evolved changes that modify the temperature sensitivity of energy demand and alter individual behaviors. Here, we aimed to test whether populations recently exposed to geothermally elevated temperatures express an altered temperature sensitivity of metabolism and behavior. We expected that long‐term exposure to warming would moderate metabolic rate, reducing the temperature sensitivity of metabolism, with concomitant reductions in boldness and activity. We compared the temperature sensitivity of metabolic rate (acclimation at 20 vs. 30°C) and allometric slopes of routine, standard, and maximum metabolic rates, in addition to boldness and activity behaviors, across eight recently divergent populations of a widespread fish species (Gambusia affinis). Our data reveal that warm‐source populations express a reduced temperature sensitivity of metabolism, with relatively high metabolic rates at cool acclimation temperatures and relatively low metabolic rates at warm acclimation temperatures compared to ambient‐source populations. Allometric scaling of metabolism did not differ with thermal history. Across individuals from all populations combined, higher metabolic rates were associated with higher activity rates at 20°C and bolder behavior at 30°C. However, warm‐source populations displayed relatively bolder behavior at both acclimation temperatures compared to ambient‐source populations, despite their relatively low metabolic rates at warm acclimation temperatures. Overall, our data suggest that in response to warming, multigenerational exposure (e.g., plasticity, adaptation) may not result in trait change directed along a simple “pace‐of‐life syndrome” axis, instead causing relative decreases in metabolism and increases in boldness. Ultimately, our data suggest that multigenerational warming may produce a novel combination of physiological and behavioral traits, with consequences for animal performance in a warming world.

Biomolecular changes in gills of Gambusia affinis studied using two dimensional correlation infrared spectroscopy coupled with chemometric analysis

The pesticide use in agriculture production at reduced cost results in increased usage. Excessive use of this is en-routed to the aquatic environment causing serious threats. Fishes are used as a bioindicator of toxicants due to pollution in the aquatic environment. These are suitable biomarkers for assessment in the ecosystem. Hence the study of pesticides toxicity in fish provides useful information about the aquatic biota. 2DCOS infrared spectral analysis gives fine spectral resolutions of overlapping bands. The enhancement in spectral resolution and overlapping bands in second dimensions is an advantage in interpreting complex spectra. The synchronous 2DCOS spectra show amide of proteins as a predominant occurring followed by phospholipids esters of fatty acids at 1771 cm−1. The asynchronous +ve and -ve cross peaks +(1651, 1691) and – (1623, 1651) results in an overlapped contribution of β sheet (1691 cm−1) with a decrease in α helix (1651 cm−1) of protein secondary structure. The principal component analysis (PCA) shows samples are well discriminated with a high loading value for 0.51 ppb (T3) treatment. The hierarchical analysis shows clustering of samples identical in nature. The Receiver Operation Characteristic analysis (ROC) validates experimental outcome as measured from the area under the curve.

Effect of environmental factors on blood counts of Gambusia affinis caught at Brantas River watershed, Indonesia.

Background: Contamination of freshwater ecosystems has become a major issue as it threatens public water sources as well as aquatic life. It is important to predict changes in organism health, given a known number of environmental factors and pollutant concentrations, in order to better manage contaminants through biomarker analysis. This study aims to examine the ecosystem health of the Brantas River based on its environmental condition and the hematology profile of Gambusia affinis fish present in the river. This species was chosen because of its wide distribution along the Brantas River, and because it is very tolerant, adaptable, highly abundant, and easy to catch. Methods: The study area included 10 sampling sites along the Brantas River watershed. In total, six water quality parameters were observed (temperature, pH, dissolved oxygen (DO), biological oxygen demand (BOD), ammonia concentration, and phenol concentration) and hematology measurements consisted of erythrocyte, leucocyte, and micronuclei analyses. Results: The results showed that the upstream area of Brantas River, located in Batu, was the least polluted region, while Mojokerto was the most polluted. The erythrocyte level of Gambusia affinis caught in most sampling sites was quite low. Furthermore, research revealed that the status of Gambusia affinis' hematological profile was significantly correlated (p<0.05) with water quality parameters, particularly DO, BOD, ammonia, and phenol. Conclusions: It can be concluded from these results that the hematological profile of the fish is poor due to high levels of organic waste and harmful substances.

Activation ofHenneguya ictaluriActinospores by Nonictalurid Fish Species, with Implications for Management of Proliferative Gill Disease in Catfish Aquaculture

AbstractProliferative gill disease (PGD), caused by the myxozoanHenneguya ictaluri, is an important parasitic disease in U.S. catfish aquaculture. Continuous exposure of Channel CatfishIctalurus punctatusto the actinospore stage ofH.ictaluriresults in a severe inflammatory response at the gills, leading to morbidity and death. Previous work indicates that the chemical cues in fish mucus that are recognized by myxozoan actinospores are not host specific. Building on these findings, the potential decoy effects of nonictalurid fish to actinospores ofH.ictaluriwere evaluated. Exposure of actinospores to gill mucus from multiple nonictalurid fishes resulted in actinospore activation for all fish species tested. Based on these findings, experimental transmission trials with potential interceptor fish were conducted. Individual Channel Catfish were co‐stocked with Western MosquitofishGambusia affinisat 0, 10, 25, or 50% of mean Channel Catfish biomass and exposed to 3,000 actinospores ofH.ictaluri. Gill tissues were sampled at 24 h postchallenge, and parasite burden was estimated byH.ictaluri‐specific quantitative PCR. Results revealed that Western Mosquitofish stocked at 25% and 50% of catfish biomass reducedH.ictaluriDNA in Channel Catfish gills more than threefold. In a second study, catfish were exposed to pond water collected from an active PGD outbreak in the presence of Western Mosquitofish stocked at 25% of catfish biomass. Channel Catfish were sampled at 24 h and at 7 d after the last pond water exposure. At 24 h postexposure, catfish that were co‐stocked with Western Mosquitofish showed significantly lowerH.ictaluriDNA than catfish stocked alone. This treatment effect was absent at 7 d postexposure, as parasite quantities within tissues had increased over 1,000×, with marked variability. Still, results indicate that the chemical cues that activateH.ictaluriactinospores are not specific to Channel Catfish. This work evinces a potential benefit of nonictalurid fish in combatingH.ictaluri, suggesting that the presence of nonictalurid interceptor fish in catfish ponds may minimize PGD severity.

Environmentally relevant arsenic exposure affects morphological and molecular endpoints associated with reproduction in the Western mosquitofish, Gambusia affinis

Arsenic (As) exposure, even at low environmentally relevant levels, may cause detrimental health outcomes through developmental toxicity and by acting as an endocrine disrupting compound (EDC). Although several studies indicate that wildlife bioaccumulate As, few evaluate the health impact on fish species in their natural environment. In the U.S., As has a drinking water regulatory limit of 10 μg/L. In many parts of Arizona, surface water and groundwater have naturally elevated levels of As from geologic deposits and contamination is exacerbated by anthropogenic activity. In aquatic environments, the Western mosquitofish, Gambusia affinis, is a good bioindicator for EDC exposure because of the distinct androgen-related development of an intromittent organ, the gonapodium, in males. We evaluated morphological and reproductive outcomes in mosquitofish exposed to As. In a laboratory experiment, juvenile male mosquitofish were exposed to sodium arsenite (0 μg/L, 0.75 μg/L, 7.50 μg/L, and 75 μg/L) for 30 days, and in a field study, populations of adult male mosquitofish were collected in Arizona waterways with As levels above and below the World Health Organization's regulatory limit. In both studies, higher As exposure was significantly associated with altered hepatosomatic indices, altered fish morphology, shortened gonopodia, and lower gonopodia-somatic indices. In the field experiment, populations from surface water with higher As concentrations exhibited lower condition factors, lower gonadal-somatic indices, distinct gonopodia shapes, and altered estrogen receptor alpha and vitellogenin gene expression; androgen receptor expression was unchanged. Together, laboratory and field results suggest that As exposure at environmentally-relevant levels affects general growth and reproductive development in mosquitofish. Observed effects may further influence individual health, mobility, or reproductive function, and because G. affinis is a species known to tolerate and adapt to a wide range of environments, it serves as a local bioindicator species as well as a model organism for parallel field and laboratory studies.

Nanostructured Lipid Carriers (NLC) for Biologically Active Green Tea and Fennel Natural Oils Delivery: Larvicidal and Adulticidal Activities against Culex pipiens.

(1) Background: The control of mosquitoes with essential oils is a growing demand. (2) Methods: This study evaluated the novel larvicidal and adulticidal activity of fennel and green tea oils and their nanostructured lipid carriers (NLC) against Culex pipiens (C. pipiens) in the laboratory, field conditions and evaluated their effect against non-target organisms. SLN type II nanoformulations were synthesized and characterized using dynamic light scattering (DLS), zeta potential and transmission electron microscope. (3) Results: The synthesized NLCs showed spherical shaped, homogenous, narrow, and monomodal particle size distribution. The mortality percent (MO%) post-treatment (PT) with 2000 ppm for 24 h with fennel oil and NLC fennel (NLC-F) reached 85% (LC50 = 643.81 ppm) and 100% (LC50 = 251.71), whereas MO% for green tea oil and NLC green tea (NLC-GT) were 80% (LC50 = 746.52 ppm) and 100% (LC50 = 278.63 ppm), respectively. Field trial data showed that the larval reduction percent of fennel oil and NLC-F reached 89.8% and 97.4%, 24 h PT and the reduction percent of green tea oil and NLC-GT reached 89% and 93%, 24 h PT with persistence reached 8 and 7 days, for NLC-F and NLC-GT, respectively. The adulticidal effects showed that NLC-F and NLC-GT (100% mortality) were more effective than fennel and green tea oils (90.0% and 83.33%), with 24 h PT, respectively. Moreover, their reduction of adult density after spraying with LC95 X2 for 15 min, with fennel oil, NLC-F, and green tea oil, NLC-GT were 83.6%, 100%, 79.1%, and 100%, respectively, with persistence (>50%) lasting for three days. The predation rate of the mosquitofish, Gambusia affinis, and the bug, Sphaerodema urinator, was not affected in both oil and its NLC, while the predation rate of the beetle, Cybister tripunctatus increased (66% and 68.3%) by green tea oil and NLC-GT, respectively. (4) Conclusions: NLCs nanoformulation encapsulated essential oils was prepared successfully with unique properties of size, morphology, and stability. In vitro larvicidal and adulticidal effects against C. pipiens supported with field evaluations have been performed using essential oils and their nanoformulations. The biological evaluation of nanoformulations manifested potential results toward both larvicidal and adulticidal compared to the essential oils themselves, especially NLC encapsulated fennel oil which had promising larvicidal and adulticidal activity.

Effect of environmental factors on blood counts of Gambusia affinis caught at Brantas River watershed, Indonesia

Background: Contamination of freshwater ecosystems has become a major issue as it threatens public water sources as well as aquatic life. It is important to predict changes in organism health, given a known number of environmental factors and pollutant concentrations, in order to better manage contaminants through biomarker analysis. This study aims to examine the ecosystem health of the Brantas River based on its environmental condition and the hematology profile of Gambusia affinis fish present in the river. This species was chosen because of its wide distribution along the Brantas River, and because it is very tolerant, adaptable, highly abundant, and easy to catch. Methods: The study area included 10 sampling sites along the Brantas River watershed. In total, six water quality parameters were observed (temperature, pH, dissolved oxygen (DO), biological oxygen demand (BOD), ammonia concentration, and phenol concentration) and hematology measurements consisted of erythrocyte, leucocyte, and micronuclei analyses. Results: The results showed that the upstream area of Brantas River, located in Batu, was the least polluted region, while Mojokerto was the most polluted. The erythrocyte level of Gambusia affinis caught in most sampling sites was quite low. Furthermore, research revealed that the status of Gambusia affinis' hematological profile was significantly correlated (p<0.05) with water quality parameters, particularly DO, BOD, ammonia, and phenol. Conclusions: It can be concluded from these results that the hematological profile of the fish is poor due to high levels of organic waste and harmful substances.

Comprehensive evaluation of the toxicity of the flame retardant (decabromodiphenyl ether) in a bioindicator fish (Gambusia affinis).

In recent years, concerns have increased about the adverse effects on health and the environment of polybrominated diphenyl ethers (PBDEs), especially BDE-209, the most widely PBDE used globally. These pollutants derive from e-waste and present different adverse effects on biota. In this work, a toxicological study on mosquitofish (Gambusia affinis) using BDE-209 (2,2',3,3',4,4',5,'5',6,6'-decabromodiphenyl ether) was carried out. Acute toxicity bioassays were conducted with daily renewal of solutions, using different concentrations of environmental relevance, ranged between 10 and 100μg L-1 of BDE-209. At 48 and 96h of exposure, several parameters were evaluated, such as mortality, individual activity (swimming), biochemical activity (catalase; thiobarbituric acid-reactive substances; and acetylcholinesterase), and cytotoxic responses (micronucleus frequencies). In addition, integrated biomarker response and multivariate analyses were conducted to study the correlation of biomarkers. The calculated Lethal Concentration-50 remained constant after all exposure times (24 to 96h), being the corresponding value 27.79μg L-1 BDE-209. Furthermore, BDE-209 induced effects on the swimming activity of this species in relation to acetylcholine, since BDE-209 increased, producing oxidative damage at the biochemical level and genotoxicity after 48h of exposure to 10 and 25μg L-1 BDE-209. The results indicate that BDE-209 has biochemical, cytotoxic, neurotoxic, and genotoxic potential on G. affinis. In addition, mosquitofish could be used as a good laboratory model to evaluate environmental stressors since they could represent a risk factor for Neotropical species.