Poecilia Reticulata Research Articles

Restless nights when sick: ectoparasite infections alter rest-activity cycles of diurnal fish hosts.

Circadian rhythms are timekeeping mechanisms responsible for an array of biological processes. Disruption of such cycles can detrimentally affect animal health. Circadian rhythms are critical in the co-evolution of host–parasite systems, as synchronization of parasite rhythms to the host can influence infection dynamics and transmission potential. This study examines the circadian rhythms in behaviour and activity of a model fish species (Poecilia reticulata) in isolation and in shoals, both when uninfected and infected with an ectoparasite (Gyrodactylus turnbulli). Additionally, the rhythmical variance of parasite activity under different light conditions as well as rhythmical variance in parasite transmissibility was explored. Overall, infection alters the circadian rhythm of fish, causing nocturnal restlessness. Increased activity of gyrodactylids on the host's skin at night could potentially contribute to this elevated host activity. Whilst migration of gyrodactylids across the host's skin may have caused irritation to the host resulting in nocturnal restlessness, the disruption in guppy activity rhythm caused by the expression of host innate immunity cannot be excluded. We discuss the wider repercussions such behavioural responses to infection have for host health, the implications for animal behaviour studies of diurnal species as well as the application of chronotherapeutic approaches to aquaculture.

Genetic and context-specific effects on individual inhibitory control performance in the guppy (Poecilia reticulata).

Among-individual variation in cognitive traits, widely assumed to have evolved under adaptive processes, is increasingly being demonstrated across animal taxa. As variation among individuals is required for natural selection, characterizing individual differences and their heritability is important to understand how cognitive traits evolve. Here, we use a quantitative genetic study of wild-type guppies repeatedly exposed to a 'detour task' to test for genetic variance in the cognitive trait of inhibitory control. We also test for genotype-by-environment interactions (GxE) by testing related fish under alternative experimental treatments (transparent vs. semi-transparent barrier in the detour-task). We find among-individual variation in detour task performance, consistent with differences in inhibitory control. However, analysis of GxE reveals that heritable factors only contribute to performance variation in one treatment. This suggests that the adaptive evolutionary potential of inhibitory control (and/or other latent variables contributing to task performance) may be highly sensitive to environmental conditions. The presence of GxE also implies that the plastic response of detour task performance to treatment environment is genetically variable. Our results are consistent with a scenario where variation in individual inhibitory control stems from complex interactions between heritable and plastic components.

Dengue Infection Survey on Prevention and Control Strategies Among Community in Malaysia

Dengue is a vector-borne disease caused by a rapidly spreading virus. Dengue vector control is considered the most efficient way for limiting and curbing the spread of the dengue virus. This study aimed to determine the perception of the Malaysian community towards prevention and control measures of Dengue infection. A total of 402 respondents in Putrajaya and Selangor participated in the survey. The questionnaire was broadly divided into three sections: i) respondent profile ii) knowledge about prevention of Dengue Fever and insecticide use for mosquito control iii) knowledge about biological control.Most of the respondents (83.0%) expressed concern regarding the effects of fogging activities on their health, whereas slightly more than half (56.0%) posited that fogging activities may have adverse environmental effects. The fogging method was reported as the most frequent method (29.2%) employed in controlling the mosquito population. Biocontrol with guppy fish scored (15.5%) and Abate® (mosquito larvae insecticide) (28.9%) were the other control measures utilised. Community perspectives revealed that 5.0% of the respondents were aware of biocontrol as a control method for the mosquito population. The biological method was considered safe for public health while guppy was reported as the most effective biocontrol agent. The introduction of novel biocontrol and successful community programmes is significantly influenced by the perception of prevention and control measures for mosquitoes.

STUDIES ON THE TOXICITY OF C-PHYCOCYANIN IN GUPPY FISH AND INFUSORIA PARAMECIUM CAUDATUM

One of the important and urgent tasks, whose successful solution depends on the supply of food to the population, is to increase the production of livestock products. Ensuring a high level of production of livestock products largely depends on the quality of feed, which is determined, first of all, by toxicological control.
 C-phycocyanin is a protein complex that belongs to phycobiliproteins and can be used as one of the potential natural components to improve the feeding of commercial fish.
 In order to establish the safety of the use of active feed components for feeding and ready-made feed into which these components are introduced, first of all, it is necessary to study their effect on the organisms of protozoa and fish, which are used for laboratory research.
 The high sensitivity of ciliates to the appearance of toxic substances in their environment and changes in their concentration led to the use of these organisms for testing the most diverse chemical elements and compounds.
 The article presents the results of studying the effect (harmlessness) of C-phycocyanin on the bodies of protozoa (Paramecium caudatum) and guppy fish.
 When studying the effect of C-phycocyanin on the body of protozoa (Paramecium caudatum), it was established that its use for 48 hours in doses of 5, 10, 25, 50, and 100 mg/l did not cause the death of ciliates. When studying the effect of C-phycocyanin on the body of guppy fish, it was established that its use in doses of 5, 10, 25, 50, and 100 mg/l did not cause the death of fish.
 So, on the basis of the conducted research, it was established that C-phycocyanin belongs to class 4, and is a non-toxic substance for Paramecium caudatum ciliates. In addition, it was established that its use in the above doses did not cause the death of fish, and its LC50 is higher than 100 mg/l.

Analysis of clasp2 Transcription Pattern in Male Germ Cells during Spermatogenesis: A Comparative Study in Zebrafish (Danio rerio) and Guppy (Poecilia reticulata)

Analysis of clasp2 Transcription Pattern in Male Germ Cells during Spermatogenesis: A Comparative Study in Zebrafish (Danio rerio) and Guppy (Poecilia reticulata)

Cylindrospermopsin exposure promotes redox unbalance and tissue damage in the liver of Poecilia reticulata, a neotropical fish species

ABSTRACT There is a growing concern regarding the adverse risks exposure to cylindrospermopsin (CYN) might exert on animals and humans. However, data regarding the toxicity of this cyanotoxin to neotropical fish species are scarce. Using the fish species Poecilia reticulata, the influence of CYN concentrations equal to and above the tolerable for drinking water may produce on liver was determined by assessing biomarkers of antioxidant defense mechanisms and correlated to qualitative and semiquantitative histopathological observations. Adult females were exposed to 0.0 (Control); 0.5, 1 and 1.5 μg/L pure CYN for 24 or 96 hr, in triplicate. Subsequently the livers were extracted for biochemical assays and histopathological evaluation. Catalase (CAT) activity was significantly increased only by 1.5 μg/L CYN-treatment, at both exposure times. Glutathione -S-transferase (GST) activity presented a biphasic response for both exposure times. It was markedly decreased after exposure by 0.5 μg/L CYN treatment but significantly elevated by 1.5 μg/L CYN treatment. All CYN treatments produced histopathological alterations, as evidenced by hepatocyte cords degeneration, steatosis, inflammatory infiltration, melanomacrophage centers, vessel congestion, and areas with necrosis. Further, an IORG >35 was achieved for all treatments, indicative of the presence of severe histological alterations in P. reticulata hepatic parenchyma and stroma. Taken together, data demonstrated evidence that CYN-induced hepatotoxicity in P. reticulata appears to be associated with an imbalance of antioxidant defense mechanisms accompanied by histopathological liver alterations. It is worthy to note that exposure to low environmentally-relevant CYN concentrations might constitute a significant risk to health of aquatic organisms.

Treatment of textile wastewater using the Co(II)/NaHCO3/H2O2 oxidation system

Textile wastewater (TWW) is one of the most hazardous wastewaters for ecosystems when it is discharged directly into water streams without adequate treatment. Some organic pollutants, such as dyes in TWW, are considered refractory compounds that are difficult to degrade using conventional chemical and biological methods. The bicarbonate-activated peroxide (BAP) system is an advanced oxidation process (AOP) based on applying H2O2, which has been demonstrated to be a clean and efficient technology for dye degradation, with the advantage of operating under slightly alkaline pH conditions. In this study, response surface methodology (RSM) based on a central composite design (CCD) was used to optimize the degradation of TWW contaminated with the azo dye Acid Black 194 using the BAP system catalyzed with cobalt ions in solution (Co2+). The analysis of variance (ANOVA) technique was applied to identify significant variables and their individual and interactive effects on the degradation of TWW. The optimum reagent concentrations for degrading TWW at 25 °C and with 45 μM Co2+ were 787.61 and 183.34 mM for H2O2 and NaHCO3, respectively. Under these conditions, complete decolorization (≥99.40), 32.20 % mineralization, and 52.02 % chemical oxygen demand removal were achieved. Additionally, the acute toxicity of textile wastewater before and after oxidation was evaluated with guppy fish (Poecilia reticulata), showing a total reduction in mortality after treatment with the Co2+–BAP system. The Co2+–BAP oxidation system is a potential method for textile wastewater treatment, which, in addition to achieving complete decolorization and partial mineralization, improves biodegradability and reduces the toxicity of the treated water.

Determining the toxicity of the biomass of Cladophora sp.

Finding new or alternative feeds, feed additives, and raw materials safe for health and the environment is significant in intensifying livestock production. At the same time, the fodder base obtained from aquatic ecosystems – algae – deserves special attention. The advantage of using algae as fodder is using small areas for their cultivation and a high reproduction rate. In addition, algae are grown where other plants cannot grow, and the productivity of algae is several times higher than that of higher plants. Algae can produce beneficial compounds and biomass, which are also used to increase the nutritional value of food products. Biomass obtained from algae is a source of necessary vitamins, minerals, proteins, polyunsaturated fatty acids, antioxidants, and other necessary nutrients. The composition of algae depends on the environment from which this biomass is collected, the conditions of algae cultivation, the season, the species of algae, and many other factors. In addition, it should be noted that some algae, out of the total amount, are toxic when consumed. That is why it is essential to research their toxicity. The article presents the results of studying the toxicity of the biomass of Cladophora sp. on the body of guppy fish. When studying the effect of biomass Cladophora sp. on the body of guppy fish, it was established that its use for 96 hours in doses of 5, 10, 25, 50, and 100 mg/l did not cause their death, and its LC50 is higher than 100 mg/l. In addition, no changes were detected in the behavior of the fish; they were active, mobile, and actively responding to external stimuli. The fish of the experimental groups were not distinguished from those of the control group.

Sexually attractive traits predict predation-threat sensitivity of male alternative mating tactics

Abstract Although visual sexual signals, such as ornamental colors and courtship displays, and large body size in males are attractive to females in numerous species, they may also inadvertently attract the attention of eavesdropping predators and thus may be costly in terms of increasing individual risk of mortality to predation. Theoretically, more color ornamented and larger males should be more predation threat sensitive and suppress their sexual signaling and(or) mating effort relatively more than their less color ornamented and smaller counterparts when under predation hazard. Here, we experimentally tested this hypothesis by quantifying concurrently the rates of alternative mating tactics (courtship displays, sneak mating attempts) expressed by male Trinidadian guppies (Poecilia reticulata) varying in color ornamentation and body size under a staged immediate threat of predation. Males suppressed their overall mating effort in response to the perceived predation threat, decreasing the frequency of their (presumably more conspicuous) courtship displays significantly more on average than the frequency of their sneak mating behavior. Statistically controlling for body length, more color-ornamented males were more threat sensitive in their courtship displays, but not sneak mating attempts, under predation hazard than drabber males. Controlling for body coloration, larger males exhibited lower courtship and sneak mating efforts than smaller males in both predation treatments, but body length only influenced threat sensitivity in sneak mating behavior. These results are consistent with both the threat sensitive hypothesis and asset protection principle and highlight the phenotype dependency and adaptive plasticity of alternative mating tactics in male guppies under varying predation risk.

Has recombination changed during the recent evolution of the guppy Y chromosome?

Genome sequencing and genetic mapping of molecular markers have demonstrated nearly complete Y-linkage across much of the guppy (Poecilia reticulata) XY chromosome pair. Predominant Y-linkage of factors controlling visible male-specific coloration traits also suggested that these polymorphisms are sexually antagonistic (SA). However, occasional exchanges with the X are detected, and recombination patterns also appear to differ between natural guppy populations, suggesting ongoing evolution of recombination suppression under selection created by partially sex-linked SA polymorphisms. We used molecular markers to directly estimate genetic maps in sires from 4 guppy populations. The maps are very similar, suggesting that their crossover patterns have not recently changed. Our maps are consistent with population genomic results showing that variants within the terminal 5 Mb of the 26.5 Mb sex chromosome, chromosome 12, are most clearly associated with the maleness factor, albeit incompletely. We also confirmed occasional crossovers proximal to the male-determining region, defining a second, rarely recombining, pseudo-autosomal region, PAR2. This fish species may therefore have no completely male-specific region (MSY) more extensive than the male-determining factor. The positions of the few crossover events suggest a location for the male-determining factor within a physically small repetitive region. A sex-reversed XX male had few crossovers in PAR2, suggesting that this region's low crossover rate depends on the phenotypic, not the genetic, sex. Thus, rare individuals whose phenotypic and genetic sexes differ, and/or occasional PAR2 crossovers in males can explain the failure to detect fully Y-linked variants.

Effect of Foeniculum vulgare Mingled Diet upon Growth, Reproduction and Spawning Performance of Guppy Fish

Naturally breeding fish cannot meet the demand of humans. So induced breeding is essential to fulfill this demand. Induced breeding ensures a timely supply of fish seeds having desired characteristics and different techniques can be used for this purpose. In this perspective synthetic hormones, extracts of pituitary hormones, Gonadotropin-releasing hormones, and sometimes Human chronic gonadotropin are used as a spawning inducer for fishes. Plant extracts can also be used as it is a new technique which could be used in aquaculture. The basic aim of our study was to enhance the growth as well as to check the effect of the traditional herb Foeniculum vulgare on the reproductive performance of Poecilia reticulata.
 Methodology: Samples were collected from a local fish shop in Sargodha. Ethanolic extract of Foeniculum vulgare seeds was prepared and mixed with different commercial feed. This feed was given to fish for 90 days to test the effect of Foeniculum vulgare seed extract on growth and reproduction performance. Water quality parameters were also maintained and recorded daily. Fecundity and Gonad somatic index were measured after dissection by removing the ovaries. Fecundity was calculated by counting the number of larvae and eggs seen with the naked eye. The hatching rate was measured by counting the number of hatching in each spawning.
 Results: According to the growth results, different levels of fennel seed extract has a significant effect on weight gain, length gain and survival rates of the fish in different groups. Statistical analysis cleared that T2 showed the highest weight and length gain. The feed Conversion Ratio decreased significantly. Results of reproduction parameters showed that the highest absolute fecundity (9.4 ± 0.19), GSI (8.69 ± 0.2) and spawning have increased in T2 followed by T1, T3, and control respectively. The observation of present research shows that Foeniculum vulgare seed extract can act as an estrogenic compound and growth promoter in commercial aquaculture.

Bioactive Potentials of Petunia Integrifolia (Hook.) Schinz & Thell. Against Culex Quinquefasciatus Larvae, Artemia Salina Nauplii and Poecilia Reticulata Adults

Petroleum ether (pet. ether), chloroform (CHCl3) and methanol (CH3OH) extracts of Petunia integrifolia (Hook.) Schinz & Thell. Whole plant was subjected to assess cytotoxicity against the brine shrimp Artemia salina L. nauplii, larvicidal activity against the mosquito Culex quinquefasciatus Say larvae and piscicidal activity against the Poecilia reticulata Peters adults. The P. integrifolia extract in pet. ether showed the highest cytotoxic activity against A. salina nauplii by giving the minimum LC50 value of 49.25 parts per million (ppm) at 48 h, while in case of CHCl3 and CH3OH extracts, the values were 63.37 and 342.55 ppm, respectively. Against C. quinquefasciatus larvae the three extracts gave LC50 values of 4.92, 5.51 and171.26 ppm, respectively all after 48 h of exposure. Against P. reticulata the LC50 values were 21.70 ppm for pet. ether extract at 48 h, and 31.91 ppm for CHCl3 extract after 42 h of exposure but CH3OH extract offered no mortality. According to the intensity of activity, therefore, the extracts could be arranged in the descending order of: pet. ether > CHCl3 > CH3OH extracts; and the sensitivity of the test organisms to the extract of P. integrifolia could be arranged in the following descending order: C. quinquefasciatus larvae (in Pet. ether; LC50 = 4.92 ppm) > P. reticulata (in pet ether; LC50 = 21.70 ppm) >A. salina nauplii (in pet. ether; LC50 = 49.25 ppm) J. Bio-Sci. 31(1): 99-108, 2023

Whole Genome Assembly and Annotation of Blackstripe Livebearer Poeciliopsis prolifica.

The blackstripe livebearer Poeciliopsis prolifica is a live-bearing fish belonging to the family Poeciliidae with high level of postfertilization maternal investment (matrotrophy). This viviparous matrotrophic species has evolved a structure similarly to the mammalian placenta. Placentas have independently evolved multiple times in Poeciliidae from nonplacental ancestors, which provide an opportunity to study the placental evolution. However, there is a lack of high-quality reference genomes for the placental species in Poeciliidae. In this study, we present a 674 Mb assembly of P. prolifica in 504 contigs with excellent continuity (contig N50 7.7 Mb) and completeness (97.2% Benchmarking Universal Single-Copy Orthologs [BUSCO] completeness score, including 92.6% single-copy and 4.6% duplicated BUSCO score). A total of 27,227 protein-coding genes were annotated from the merged datasets based on bioinformatic prediction, RNA sequencing and homology evidence. Phylogenomic analyses revealed that P. prolifica diverged from the guppy (Poecilia reticulata) ∼19 Ma. Our research provides the necessary resources and the genomic toolkit for investigating the genetic underpinning of placentation.

No Sex-Specific Effects of Artificial Selection for Relative Telencephalon Size during Detour Learning and Spatial Discrimination in Guppies (Poecilia reticulata)

Over recent decades, substantial research has focused on fish cognitive evolution to increase our understanding of the evolution of the enormous diversity of cognitive abilities that exists in fishes. One important but understudied aspect of cognitive evolution is sexual dimorphism in cognitive abilities. Sex-specific variation in brain region morphology has been proposed to be an important mechanism in this context. However, it is also common to find sex-specific variation in behavior and cognition without associated differences in brain morphology among the sexes. The telencephalon is the major cognitive center in the vertebrate brain and variation in telencephalon size has been associated with variation in cognition. Here, we utilize recently developed guppy artificial selection lines with ca. 10% differences in relative telencephalon size to investigate whether similar responses to selection of the size of this region may affect cognitive abilities differently in males and females. To that end, we compared two ecologically relevant aspects of cognition, detour learning and binary spatial discrimination. We tested the significance of the interaction between telencephalon size and sex, and we found no sex-specific effects of evolutionary increases in telencephalon size in the cognitive abilities tested. This study indicates that no clear cognitive sex-specific effects occur in response to rapid selection of telencephalon size. We suggest that future research on sexual dimorphism in cognitive abilities in fish could use various cognitive tests and examine telencephalic sub-regions to gain a more comprehensive understanding of their evolution.

Aggregation of symbionts on hosts depends on interaction type and host traits

Symbionts tend to be aggregated on their hosts, such that few hosts harbor the majority of symbionts. This ubiquitous pattern can result from stochastic processes, but aggregation patterns may also depend on the type of host–symbiont interaction, along with traits that affect host exposure and susceptibility to symbionts. Untangling how aggregation patterns both within and among populations depend on stochastic processes, interaction type and host traits remains an outstanding challenge. Here, we address this challenge by using null models to compare aggregation patterns in a neutral system of Balanomorpha barnacles attached to patellid limpets and a host–parasite system of Gyrodactylus spp. monogeneans and their Trinidadian guppy Poecilia reticulata hosts. We first used a model to predict patterns of symbiont–host aggregation due to random partitioning of symbionts to hosts. This null model accurately predicted the aggregation of barnacles on limpets, but the degree of aggregation varied across 303 quadrats. Quadrats with larger limpets had less aggregated barnacles, whereas aggregation increased with variation in limpet size. Across 84 guppy populations, Gyrodactylus spp. parasites were significantly less aggregated than predicted by the null model. As in the neutral limpet–barnacle system, aggregation decreased with mean host size. Parasites were significantly less aggregated on males than females because male guppies tended to have higher prevalence and lower parasite burdens than predicted by the null model. Together, these results suggest stochastic processes can explain aggregation patterns in neutral but not parasitic systems, though in both systems host traits affect aggregation patterns. Because the distribution of symbionts on hosts can affect symbiont evolution via intraspecific interactions, and host behavior and evolution via host–symbiont interactions, identifying the drivers of aggregation enriches our understanding of host–symbiont interactions.

A class of their own? Water-soluble polymer pollution impacting a freshwater host-pathogen system

While the inclusion of synthetic polymers such as primary microplastics within personal care products have been widely restricted under EU/UK Law, water-soluble polymers (WSPs) have so far slipped the net of global chemical regulation despite evidence that these could be polluting wastewater effluents at concentrations greatly exceeding those of microplastics. Polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) represent WSPs with common industry and household uses, down-the-drain disposal and a direct route to wastewater treatment plants, conveying high risk of environmental leaching into freshwater ecosystems. The current study is the first investigating the impacts of predicted environmental concentrations of these WSPs on life-history traits of two freshwater species also constituting a disease model (fish - Poecilia reticulata and parasite - Gyrodactylus turnbulli). Single effects of WSPs on fish as well as their interactive effects with infection of the ectoparasite were determined over a 45-day exposure. Generally, WSPs reduced fish growth and increased routine metabolic rate of fish implying a depleted energetic budget, however these effects were dose, exposure time and polymer dependent. Parasitic infection alone caused a significant reduction in fish growth and enhanced fish routine metabolic rate. In contrast, a non-additive effect on metabolic rate was evident in fish experiencing simultaneous infection and WSP exposure, suggesting a protective effect of the two WSPs for fish also exposed to a metazoan ectoparasite. Off-host parasite survival was significantly lowered by both WSPs; however, parasite counts of infected fish also exposed to WSP were not significantly different from the control, implying more complex mechanisms may underpin this stressor interaction. Distinct detrimental impacts were inflicted on both organisms implying environmental leaching of WSPs may be causing significant disruption to interspecies interactions within freshwater ecosystems. Additionally, these results could contribute to sustainable development in industry, as we conclude PVA represents a less harmful alternative to PVP.

Effects of the invasive fish Poecilia reticulata on the behavioral response of Daphnia pulex to the exotic submerged macrophyte Egeria densa

AbstractThe high-elevation plateaus of the inter-Andean valleys are home to shallow lakes that have become eutrophic. These lakes share similarities with shallow lakes in temperate and subtropical areas. Because native species diversity is low, invasive species dominate the fish and macrophytes communities. The study aimed to investigate the behavioral response of the local Daphnia pulex from the Andean shallow Lake Yahuarcocha to the exotic submerged macrophyte Egeria densa and the exotic fish Poecilia reticulata. Laboratory habitat choice experiments revealed that D. pulex from Lake Yahuarcocha strongly avoid E. densa, irrespective of the presence of the fish P. reticulata or chemical cues indicating fish predation on D. pulex. This observation could be explained by the fact that P. reticulata displayed a strong attraction to E. densa during the daytime, probably to avoid bird predation. D. pulex from the nearby Lake San Pablo where P. reticulata is absent but where the fish community is dominated by Oncorhynchus mykiss displayed the same avoidance behavior to submerged macrophytes as D. pulex from Lake Yahuarcocha. These results indicate that macrophytes in these high-elevation shallow lakes may not facilitate top-down control of phytoplankton, since plants do not offer refuge to D. pulex from fish predation.

Immune challenge changes social behavior in the guppy (Poecilia reticulata)

Abstract Increased exposure to pathogens is often considered to be one of the most significant costs of group living. As a result, animals typically avoid close association with individuals who manifest symptoms of disease. The question remains, however, whether avoidance behaviors are mediated by effects relating specifically to the disease itself, or through recognition of more general sickness behaviors that emerge from the activity of the immune system in response to infection. Here we examined the effects of an immune challenge, induced through exposure to bacterial lipopolysaccharides (LPS), on individual and social behavior in female guppies (Poecilia reticulata). We found that in a binary choice presentation, healthy focal individuals showed a strong preference to associate with stimulus shoals of saline-injected fish rather than stimulus shoals of LPS-injected fish. In a subsequent examination of group-level dynamics, shoals of LPS-injected females were more dispersed than similar shoals comprised of control fish and showed less coherent collective behavior despite the lack of any obvious difference in general activity between LPS and control fish. We discuss these findings in relation to the need for social animals to mitigate the risk of disease that is associated with living in proximity to conspecifics.

Evaluation of the Insecticidal Potential of Heterotheca inuloides Acetonic and Methanolic Extracts against Spodoptera frugiperda and Their Ecotoxicological Effect on Poecilia reticulata.

For the management of Spodoptera frugiperda, botanical extracts have been used to reduce the environmental impacts of synthetic chemical pesticides. In the present investigation, the insecticidal activity of the acetonic and methanolic extracts of Heterotheca inuloides (Asteraceae) and of the main compound 7-hydroxy-3,4-dihydrocadalene on this pest as well as its ecotoxicological effect on Poecilia reticulata were evaluated. A greater insecticidal response was obtained from the acetonic extracts than from the methanolic extracts, with LC50 values of 730.4 ppm and 711.7 ppm for samples 1 and 2, respectively. Similarly, there was a lethal effect on 50% of the P. reticulata population at low concentrations in the acetonic extract compared to the methanolic extract. The sesquiterpene 7-hydroxy-3,4-dihydrocadalene has greater insecticidal activity by presenting an LC50 of 44.36 ppm; however, it is classified as moderately toxic for guppy fish.

Interspecific differences in developmental mode determine early cognitive abilities in teleost fish

Most studies on developmental variation in cognition have suggested that individuals are born with reduced or absent cognitive abilities, and thereafter, cognitive performance increases with age during early development. However, these studies have been mainly performed in altricial species, such as humans, in which offspring are extremely immature at birth. In this work, we tested the hypothesis that species with other developmental modes might show different patterns of cognitive development. To this end, we analysed inhibitory control performance in two teleost species with different developmental modes, the zebrafish Danio rerio and the guppy Poecilia reticulata, exploiting a simple paradigm based on spontaneous behaviour and therefore applicable to subjects of different ages. Zebrafish hatch as larvae 3 days after fertilisation, and have an immature nervous system, a situation that mirrors extreme altriciality. We found that at the early stages of development, zebrafish displayed no evidence of inhibitory control, which only begun to emerge after one month of life. Conversely, guppies, which are born after approximately one month of gestation as fully developed and independent individuals, solved the inhibitory control task since their first days of life, although performance increased with sexual maturation. Our study suggests that the typical progression described during early ontogeny in humans and other species might not be the only developmental trend for animals’ cognition and that a species’ developmental mode might determine variation in cognition across subjects of different age.