Introduction Habitat degradation, changes to hydrology, over-harvest, and hatchery practices have contributed to the decline of salmon populations in California over the past two centuries. The accumulation of these stressors led to such low salmon population numbers in California’s Central Valley that Sacramento River winter-run Chinook salmon (SRWRC; Oncorhynchus tshawytscha ) were federally listed as endangered in 1994. Since then, significant effort and resources have gone towards supporting the recovery of these populations, including habitat restoration, hydrology modifications, harvest restrictions, and revisions to hatchery management practices. Despite these efforts, the SRWRC population remains at risk. There is an urgent need to explore what combination of management actions are needed to substantially improve their status. Methods In this study, we use a long-term population dynamics model, specifically an updated version of the Winter-run Chinook salmon life cycle model (WRLCM), to evaluate a large suite of potential recovery scenarios that include both singular actions and multiple actions to identify which scenarios best support population recovery of endangered SRWRC. The WRLCM couples water-planning models, hydrodynamic models, habitat capacity models, and life stage-specific survival models within an encompassing stage-structured salmon life cycle model, to predict how SRWRC will respond to changes in suites of management actions. We evaluated scenarios that included increased quantity and quality of rearing, outmigration, and spawning habitat, modified reservoir operations to increase egg survival, reduced incidental harvest in ocean fisheries, and modified hatchery practices. Results Our results demonstrate that no singular recovery action was sufficient to achieve recovery objectives over a 26-year simulation period (1995–2020), but scenarios that included multiple actions could increase total population size by over 7 times the historical population size, without the need for hatchery supplementation. These results illustrate the synergistic effects that habitat, flow and other actions can have when taken in concert. Discussion Our results indicate that a holistic, multi-faceted set of recovery actions will likely be required to recover endangered winter-run Chinook salmon in the Sacramento River.

ABSTRACT In temperate regions, the survival of Aedes (Stegomyia) aegypti (L.) populations during the unfavourable cold season depends on the ability of eggs to overwinter and produce viable larvae the following spring. This strategy would involve changes in egg traits depending on when they are laid. The present study aimed to assess differences in some traits of eggs laid in the field in summer and autumn in the temperate region of Argentina. The traits compared were egg survival, spontaneous hatching, hatching response, developmental time until adult emergence and wing length of emerged adults. Eggs laid in summer and autumn were collected in the field and stored under constant temperature (15°C) and photoperiod (12L:12D) for 124 days (storage period). All eggs were 2–9 days old at the time of storage. At the end of the storage period, eggs were immersed for hatching at constant temperature (23°C) and photoperiod (12L:12D). After hatching, larvae were reared until adult emergence in a thermal bath at constant temperature (23°C) and photoperiod (12L:12D), and fed ad libitum. Eggs laid in autumn showed higher survival, lower proportion of spontaneous hatching and lower hatching response than did eggs laid in summer. Adults from eggs laid in autumn had longer wings and shorter developmental time than those from eggs laid in summer. Our results suggest that in Ae. aegypti the strategy to deal with seasonality affects various offspring traits.

The “twofold cost of sex” is one of the greatest mysteries in evolutionary biology. In anisogamy (fertilization between egg and sperm), since half the offspring produced by the mother are male, to compete with thelytoky—which produces only females—in terms of reproductive rate, the number of daughters × juvenile survival probability must be doubled. The genetic benefits of sex (e.g., Red Queen) are too slow to suppress quickly increasing thelytoky. Here, I propose the “Double-Income Anisogamy” hypothesis. Resource defense by males is observed across many taxa, from insects to humans. To attract many females, males defend patches containing the resources necessary for offspring development. Since males only allow access to resources to females that accept mating, thelytokous females are eliminated. Thus, thelytokous females incur the “cost of being single”. Anisogamous females already achieve the same egg number (although half of which are males) and survival rates as thelytokous females using their own resources alone (single-income situation). If anisogamous females use resources from males (double income) to increase not the number of eggs but the survival rate of existing offspring, the number of surviving daughters (fitness) doubles, offsetting the twofold cost without considering genetic benefits. Simulations confirmed the model predictions.

Labeo rohita, also known as rohu, is an important type of fish found in India. It has become a major part of the fish population in the Gandhi Sagar Reservoir (GSR) because it was intentionally introduced as part of a planned stocking program. This man-made lake is located in Madhya Pradesh, on the Chambal River. Originally, the lake had only native fish species, but now rohu and Catla catla make up a large part of the fish caught there.Growth and Development: L. rohita in the reservoir grows steadily and consistently because the water environment is good and there is not too much competition for food and space. In ideal farming conditions, this fish can grow to 500–1,000 grams in one year. In natural river systems, the fastest growth happens in the first year, such as 34.6 cm in one study, and then slows down as the fish gets older. The species usually starts breeding in its second year. The relationship between the length and weight of L. rohita in similar environments often shows that weight increases a little slower than the cube of its length, called negative allometric growth. However, some studies in other areas have found that the growth is proportional, called isometric growth. Lifespan: Studies on L. Rohita in river systems have found that some fish can live up to 11 years. One study recorded a fish of this age. The maximum age generally recorded is close to 10 years. Gandhisagar Dam is located at 22°04′N and 75°22′E, on the border between Madhya Pradesh and Rajasthan. The reservoir spans an area of 660 km². When the dam is full, the water level is 399.9 meters, with an average area of 402 km². The maximum length of the reservoir is 67.8 km, and the maximum width is 26.1 km. Construction of the dam started in 1954 and was completed in 1960. Over 228 villages were either completely or partially submerged due to the flooding caused by the dam. Full submergence happens when the water level reaches around 50 meters, but due to low rainfall in the last three years, the dam's capacity utilization has dropped by more than 40%. During the study period in December to January 2001–2002, the water level was 381.9 meters, which reduced the area of submergence by about 250 km². Many large islands became visible again in the reservoir, and the state government allocated large areas on both banks for farming. Conservation Methods: Managing L. rohita in the Gandhi Sagar Reservoir involves several strategies to make sure the fish population stays healthy and the fishery is sustainable. Stocking Support: Keeping up with stocking young fish and fingerlings is an important management activity, especially as the reservoir environment may affect natural reproduction. RegulatoryMeasures: Laws are important for managing the fishery. These include setting closed season when fishing is not allowed, creating protected areas, and controlling fishing nets to keep them from catching baby fish. Habitat Management: The physical features of the reservoir, such as shallow areas, pools, and gorges, offer necessary feeding and sheltering spots for the fish. Cooperative Management: Working with and organizing local fishermen into cooperatives helps manage fishing Because of improvements in multiple spawning of carps, there is a growing need for high-quality larval diets. Larval fish lack the right enzymes or enough digestive enzymes to process feed efficiently. This means that breaking down feed ingredients into simpler nutrients using bacterial enzymes may help these young fish. Five experimental diets (D1–D5), each with the same calorie and protein content, were made with 32% fish meal, 34% mustard oil cake, 30% rice bran, and 2% cod liver oil. These diets were fermented in a lab using Bacillus circulans bacteria (at a rate of 108 cells per gram) at 37°C for 1 to 5 days. The bacteria used came from the intestines of young rohu fish (Labeo rohita). A non-fermented diet (RD) was also tested. Rohu eggs (average weight 0.35 mg) were given these diets freely for 21 days, feeding them every half hour from 9 a.m. to 4 p.m. Results fermenting the diets increased the amount of protein and free amino acids, while reducing crude fiber. Diets fermented for 4 and 5 days (D4 and D5) led to the best growth and survival (98% and 98.33%) of rohu eggs compared to other diets. A strong positive link was found between the RNA:DNA ratio and specific growth rate across 18 dietary groups (6 groups tested in triplicate).

Soil Transmitted Helminthiases (STH) are among the most common neglected tropical diseases in Nigeria, primarily transmitted through soil contaminated with human feces, which prompted this research on the effect of ecological factors such as soil temperature on the distribution of STH in Nigeria. Environmental factors, particularly soil temperature, play crucial roles in determining STH distribution patterns by influencing helminth egg development and survival rates Given the Global Epidemiological Studies on how STH infection prevalence suggest significantly that land surface temperature, and how the use of Random Forest and particle Swarm Optimization can significantly improve the accuracy of species distribution predictions of STH using Soil temperatures compared to conventional modelling approaches. In this paper, we propose a hybrid model combining the widely used Random Forest Algorithm and Particle Swarm Optimization Algorithm for feature selection and hyperparamter optimization using dataset from ESPEN based on Nigeria Geographical region, and a comprehensive analysis of the STH dataset, a novel hybrid model whose main goal is to produce the accurate decision trees and also determine the best predictor or features, in this approach, an hybrid model was used for feature selection instead of relying on the conventional Random Forest feature selection with the use of random sampling by the training sets, The model’s predictive performance was evaluated against traditional Random Forest and Artificial Neural Network algorithms using accuracy metrics. Our model was compared with a deep learning Artificial Neural Network algorithm, RFPSO with 91.40% accuracy, RF with 87% and ANN with 80.97%. Particle Swarm Optimization with Random Forest algorithms integration substantially enhances the accuracy of STH distribution modeling, particularly when incorporating soil temperature data. This hybrid approach offers improved feature selection capabilities and represents a significant advancement over conventional modeling techniques for parasitic disease distribution prediction.

Lentils (Lens culinaris Medikus, 1787) and faba beans (Vicia faba Linnaeus, 1753) are important crops in France facing threats from Bruchus spp. We analyzed 59 lentil and 45 faba bean fields across four French regions over three growing seasons (2019-2020 to 2021-2022). We investigated the diversity, colonization patterns and spatiotemporal distribution of bruchids at different crop phenological stages and distances from field edges. Bruchus rufimanus Boheman, 1833 and Bruchus signaticornis Gyllenhal, 1833 were the only species emerging from faba beans (97.8%) and lentils (99.5%), respectively. B. rufimanus colonization was concentrated during pod development, maintaining a balanced male-female ratio throughout. B. signaticornis exhibited a colonization period of ≈1 month, with a gradual increase in female proportion over time. The spatial distribution of bruchids and damage were relatively uniform within fields, indicating strong dispersal capabilities. A significant positive correlation, with a high degree of dispersion, was identified between female abundance and bruchid-damaged grains. We confirmed that B. rufimanus and B. signaticornis were the only species damaging faba beans and lentils in France, respectively. The homogeneous spatial distribution suggests a strong dispersal ability of bruchids. The high degree of dispersion in the relationship between female abundance and bruchid-damaged grains highlights the importance of regulatory factors influencing larval and egg survival. These results, together with the presence of B. signaticornis in faba beans, emphasize the need for species-specific, phenology-based and spatially informed integrated pest management strategies, to mitigate the impact of bruchids and reduce reliance on chemical in their control. © 2026 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

This study compares the survival of hookworm eggs and Strongyloides stercoralis first-stage larvae (L1) in septic tank sludge. Laboratory evidence suggests these helminths differ in survivability, but real-world data are lacking. We enrolled 24 households, each with at least one member positive for S. stercoralis and at least one member positive for hookworm. Each member used their own household latrine for defecation. We collected stool samples from 112 individuals, followed by sludge sampling from 24 septic tanks 2 weeks later. Stool samples were examined using agar plate culture (APC) and a modified formalin-ether concentration technique (MFECT) to detect and count hookworm eggs, S. stercoralis L1, and other helminth eggs. In parallel, sludge samples were analysed using an APC method to detect hookworm third-stage larvae (L3) and S. stercoralis (L3 and free-living stages). Hookworm L3 were positive in 48 sludge samples from 24 households collected from septic tanks of 24 latrines where hookworm-positive members defecated. In contrast, no S. stercoralis L3 or free-living males and females were found in 48 sludge samples from 24 septic tanks with S. stercoralis-positive household members defecating in latrines. Hookworm eggs can survive in septic tank sludge, but S. stercoralis L1 cannot be detected using APC in 48 sludge samples. Thus, managing hookworm eggs in sludge is important, whereas special measures for S. stercoralis may not be needed. Using latrines effectively helps control strongyloidiasis.

Evaluating the ecological effects of daily hydropeaking on lithophilous fish spawning habitat in a large mountainous river.

The two recently described species, Acanthosaura cuongi and A. grismeri in southern Vietnam, highlight the potential existence of additional populations or even undescribed species in this region, rather than supporting the previous assumption that Acanthosaura coronata is broadly distributed across southern Vietnam. Phylogenetic analysis of COI gene sequences confirmed the monophyly of the A. coronata group, comprising A. coronata, A. cuongi, and A. grismeri. In southern Vietnam, two new populations from Gia Lai Province were assigned to A. cuongi, while one new population from Tay Ninh Province was identified as A. coronata. Within the group, interspecific p-distances ranged from 7.82–8.77% between A. coronata and A. grismeri, to 13.5–14.92% between A. coronata and A. cuongi, and 13.84–15.19% between A. cuongi and A. grismeri. Intraspecific genetic divergences were up to 3.22% in A. cuongi and 2.66% in A. coronata, suggesting potential cryptic diversity and emphasizing the need for further taxonomic assessment using additional molecular data. Based on morphological data from 66 individuals, this study provided a comprehensive redescription of A. coronata species and documented distinct sexual dimorphism. Males exhibit light green to yellow-green dorsal coloration and an orange-red tail likely functioning in sexual signaling, whereas females display dull brown-gray coloration enhancing camouflage. Morphometric analyses revealed female-biased traits, including greater snout–vent length and abdominal width, potentially improving fecundity and egg survival. Conversely, males possess longer heads, limbs, and broader tail bases, which may facilitate greater agility and provide advantages in hunting, territorial defense, and reproductive success. These findings contribute to a better understanding of morphological variation, sexual dimorphism, and taxonomic relationships within the complex A. coronata group.

Urbanization is intensifying human interactions with mosquitoes, exacerbating public health challenges. Densely populated areas provide ideal conditions for container-dwelling mosquitoes, with increased host availability and the presence of artificial breeding sites. These anthropophilic mosquitoes often exhibit distinct ecological adaptations compared to their rural counterparts. Since mosquito eggs are immobile and remain at the site of oviposition, they provide a valuable lens for assessing how urbanization, climate-driven shifts in temperature, and drought affect mosquito reproductive success. This study examined Ae. aegypti egg viability under varying temperature and dry conditions over five months, focusing on lineages with distinct ancestries from West African populations. Mosquitoes collected from urban habitats with a high human preference demonstrated higher egg survival under prolonged arid conditions. Analysis of climatic factors revealed that dry season temperature and precipitation during wet periods are significant predictors of egg drought tolerance. Modeling future climate scenarios based on input from our egg viability results suggests a projected shift and expansion in the seasonal survival window for Ae. aegypti by the end of the century. This study highlights the importance of understanding environmental constraints on the drought tolerance of mosquito eggs to predict and mitigate future mosquito outbreaks.

ABSTRACTUrbanisation impacts biodiversity in coastal ecosystems. Conservation management is needed to improve species persistence in such areas where populations have become small and fragmented. We conducted a population viability analysis to compare management scenarios for an isolated population of the threatened green and golden bell frog (Litoria aurea) in a peri‐urban area of coastal south‐east Australia. The breeding population occupies a single wetland that is hydrologically connected to an intermittently open lagoon. The lagoon is periodically drained to reduce flood risk to residential areas, influencing the reproductive output of the population. We combined estimates of population size, demographics, dispersal and genetic diversity to compare the relative probability of local extinction over a 25‐year forecast window under four management scenarios: (1) lagoon draining at historic rates (status quo); (2) halving the incidence of lagoon draining; (3) creating new breeding habitat; and (4) supplementing the population. Our modelling predicted that the population had a 60% probability of extinction under the status quo scenario, while halving the frequency of lagoon draining or creating a new but hydrologically distinct wetland nearby reduced the probability of extinction to 6%. Predictions of population size at the end of the forecast period never reached zero when 10 adults were supplementing the population each year. Our analysis suggested that this L. aurea population will likely go extinct if the current frequency of lagoon draining continues. We believed the most cost‐effective strategy to improve the persistence of the population over a 25‐year management horizon is to reduce how often the lagoon is drained so that sufficient water remains in the wetland to support egg and tadpole survival. We highlighted that artificially manipulating the hydrology of coastal environments to reduce flood risk can compromise the persistence of hydrology‐dependent species.

Rainbow trout (Oncorhynchus mykiss) constitute an important component of cold-water aquaculture, yet breeding performance in high-altitude hatcheries remains insufficiently documented, particularly in the northern regions of Pakistan. This study evaluated artificial breeding outcomes at the Shino Hatchery, Kaghan Valley, situated at ~2,100 m elevation, during the December 2024–January 2025 spawning season. Gametes were collected from 24 females and 13 males, yielding a total of 22,870 eggs. Artificial fertilization resulted in a mean fertilization success exceeding 92%, with 21,061 viable eggs retained for incubation. Unfertilized eggs accounted for less than 8% of the total, reflecting strong gamete compatibility and effective broodstock and hatchery management. A declining trend in fertilization efficiency and egg survival was observed in late-season spawns, likely associated with broodstock aging and progressive deterioration of gamete quality. Overall, artificial breeding at this high-altitude facility produced substantially higher fertilization and early-survival rates than those typically observed under natural spawning conditions. These findings highlight the potential of controlled breeding interventions to enhance rainbow trout seed production and support the expansion of cold-water aquaculture in northern Pakistan.

The results of a study on pikeperch triploidization using hydrostatic pressure shock (7000 PSI) applied 5 min after fertilization with varying exposure durations of 5 and 10 min are presented. It was shown that both protocols yielded close to 100% triploidy rate. Egg survival during the incubation period was higher with the shorter pressure exposure: after a 5-min exposure, the survival rate was 77,9 %, after 10 min –73,4 %, and in the control group –88,4 %. Rearing triploid pikeperch to the fingerling stage revealed their growth retardation from larvae weighing 50-70 mg and reduced survival compared to diploids: the final mass and survival rate of triploids were 3,5 g and 46,4 %, respectively, while for diploids, these values were 4,0 g and 77,5 %.

ABSTRACT Objective Anthropogenic disturbances led to the decline and extirpation of Arctic Grayling Thymallus arcticus populations in the continental United States, prompting renewed interest in restoration via early life stage stocking. Remote site incubators (RSIs) have been used successfully to support instream egg incubation, but their dependence on relatively steep stream gradients limits applicability in low-gradient systems, such as those in Michigan’s Lower Peninsula. We evaluated the performance of a novel, low-cost floating basket incubator (FBI) as an alternative rearing device for low-gradient streams targeted for Arctic Grayling reintroduction. Methods We compared egg-to-fry survival of Rainbow Trout Oncorhynchus mykiss, Brook Trout Salvelinus fontinalis, and Walleye Sander vitreus in paired RSI and FBI deployments across hatchery and field settings. To statistically analyze results, we used random-effects meta-analysis, one-way ANOVAs, and generalized linear models. Results A random-effects meta-analysis indicated similar survival between incubator types, with the difference in survival (i.e., RSI − FBI) averaging 2.97 percentage points (95% CI = −3.15 to 9.09). Despite slightly lower survival relative to RSIs, the FBIs had four times more egg capacity per unit, required significantly less labor and material to deploy, and functioned with minimal maintenance in low-velocity stream environments. Using generalized linear models, we identified stream location and percent fungus as the strongest predictors of Rainbow Trout egg survival in FBIs. Conclusions Our results support the use of FBIs for Arctic Grayling restoration in low-gradient systems by offering a scalable, efficient, and field-deployable tool for instream incubation, with performance comparable to that of traditional RSIs under typical field conditions.

The work examines the drift of pollock eggs and larvae in the Pacific Ocean region adjacent to the southeastern coast of the Kamchatka Peninsula and the northern Kuril Islands. A model approach is used, combining particle trajectory calculations using the ICHTHYOP software, ocean reanalysis data, and the results of a regional tidal model. The eggs and larvae are considered as passive tracers, and their transport from the main spawning ground of the East Kamchatka pollock in the deep-water canyon of the Avacha Bay was calculated for one month in 2024 and 2025, starting from the observed spawning date in April. The main objective of the modelling was to determine the influence of various dynamic factors on particle transport and the likely locations of their accumulation, where egg development and larval hatching may occur. Identifying these locations through ichthyoplankton surveys is very difficult. The model calculations did not take into account a number of factors related to the mortality of eggs and larvae under the influence of environmental changes and predation, larval activity during development, and other processes of physical and biological interaction. The transport of tracers after their ascent to the surface in the spawning area was analyzed using background surface currents and those averaged over the upper sea layer. The simulation results show that the predicted horizontal particle trajectories depend not only on the different hydrodynamic conditions for the two years, but also on the consideration of tidal drift. A hypothesis has been put forward regarding the dynamic conditions favorable for the development and survival of pollock eggs and larvae, under which their drift does not lead to their transport from the shelf water into the open ocean. Potential areas of particle accumulation in coastal waters have been identified.

Preserving viable infective stages of chicken ascarids under laboratory conditions facilitates the maintenance of characterized nematode strains for research purposes. We investigated the survivability of Ascaridia galli eggs exposed to low temperatures and the cryoprotectant dimethyl sulfoxide (DMSO). Two egg developmental stages (unembryonated or fully embryonated) were stored at 4°C, -20°, or -80°C in sterile water or with 5% and 10% DMSO for 1, 2, 4, or 8 weeks. Egg survival was assessed by morphology following post-storage incubation in 0.1 N H2SO4 at 26°C for unembryonated eggs or with a viability dye exclusion test of hatched larvae for the embryonated eggs. The results revealed that neither DMSO nor the hardy chitinous eggshell protected eggs from freezing damage, and not a single egg survived even for 1 week of storage at -20° or -80°C. DMSO at 10% significantly reduced (P < 0.0001) overall egg survival and embryonation capacity with increasing storage time at 4°C compared to water alone. For both egg developmental stages, egg survival was maintained in 5% DMSO at a rate similar to that in water alone. Unembryonated A. galli eggs survived refrigeration better than embryonated eggs with larval viability declining linearly at almost a double rate in the latter (9.75%/week) compared to the former (5.64 %/week). We conclude that DMSO is unlikely to provide cryoprotection for A. galli eggs and also causes concentration-dependent toxicity with increasing exposure time. Furthermore, survival during refrigeration is better for unembryonated than embryonated eggs.

Background: Toxocariasis is a globally important zoonotic infection acquired through contact with soil contaminated by Toxocara eggs. Despite its relevance, comprehensive data on environmental contamination across Iran’s climatic zones are lacking. We assessed the presence of Toxocara eggs in public park soils with emphasis on climatic and seasonal variation. Methods: A cross-sectional survey was conducted from summer 2024 to spring 2025 in three climatic zones of Iran (Mountain, humid, and hot–dry). A total of 1,445 soil samples were randomly collected from a depth of 4–5 cm. Samples were examined using sucrose flotation and direct smear techniques. Microscopic identification of eggs was performed at 400× magnification. Results: Toxocara eggs were detected in all regions studied. The humid zone showed the highest contamination rate, reaching 51% in summer. In the mountain zone, prevalence peaked in spring (44%) and was lowest in winter (12%). In the hot–dry zone, the highest contamination occurred in autumn (32%) and the lowest in summer (14%). These differences indicate the influence of climatic and seasonal conditions on egg survival. Conclusion: The widespread detection of Toxocara eggs in public park soils highlights a considerable risk for human exposure, particularly among children. Improved environmental hygiene, responsible pet management, and public education are required. Future studies should incorporate molecular confirmation and longitudinal monitoring within a One Health framework to support targeted interventions.

Ectothermic organisms are highly sensitive to ambient temperature, and exposure to extreme heat can induce a range of lethal and sublethal effects. Spiders are abundant and ubiquitous arthropod predators in most terrestrial ecosystems and studying their responses to different temperature regimes provides valuable insights into effects of temperature on this important group of organisms. Here, we exposed the false widow spider (Steatoda grossa), either as eggs or spiderlings to different temperature regimes and monitored their survival and development. The regimes were set at 22/12°C (day/night), 27/17°C, 32/22°C, or were simulated as heatwaves in which the days at 32/22°C were restricted. Egg and spiderling survival decreased with higher temperature exposure. The growth trajectories of female spiderlings exposed to thermal stress after hatching were stronger affected by the various regimes than those of males. Only the males, which develop much faster than females, reached adulthood and those reared at lower temperatures grew slower but attained significantly more adult body mass. Male spiderlings and, to a lesser extent, eggs and female spiderlings, were able to withstand transient exposure to 32°C during simulated heatwaves. Our study shows that eggs and young spiderlings are highly sensitive to high temperatures and that female spiderlings are more sensitive than males. Female spiders of this species are mostly sedentary and spend their entire lives in relatively small webs, whereas adult males wander in search of females. Given the higher sensitivity of females and eggs to high temperatures, we argue that females are under strong selection to build webs and place egg sacs at sites where temperatures exceeding 30°C are avoided.

Eradicating insects from small bodies of water without resorting to environmentally harmful methods is a challenge worldwide. Among the practices used to treat the water waste of arthropod containment facilities, chlorination is still used, despite the known impacts of chlorine byproducts on the environment and limited scientific literature documenting its potency against arthropods. Here, we evaluated the efficacy of chlorination as a means to kill insects in water by immersing eggs of the Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritidae) in 10 solutions containing different concentrations of chlorine ranging from 0 to 65,000 ppm for a duration of 4, 24, and 48 h, and measuring egg survivorship. Results showed that egg survivorship was negatively correlated with chlorine concentration and immersion duration. The rate of decrease in egg survivorship due to chlorine was steeper as immersion duration increased. However, egg mortality never reached 100% even with the highest chlorine concentration, and concentrations < 2000 ppm had little effect on eggs. Our results demonstrate clearly that chlorination is not an effective treatment method to ensure insect eradication from wastewater. More effective alternative methods, such as heat treatment, are preferable.

The effect of graded level of normal saline solution on fertilization rate, hatchability and survival of Clarias gariepinus fry was conducted in Department of Aquaculture and Fisheries Management, Nasarawa State University Keffi. six (6) brood stocks of C. gariepinus consisting of 3 males and 3 females were used for the study. Sodium chloride was weighed at 0g/l, 2.25g/l, 4.50g/l, 6.75g/l and 9.00g/l using a sensitive weighing balance representing T1, T2, T3, T4, and T5 respectively. Milt was squeezed and washed into already prepared concentrations (0, 2.25, 4.50, 6.75 and 9.00 g/l) of physiological saline to keep the sperm dormant but alive. Statistical analysis was carried out on all data using ANOVA with STAR and means were separated at 95% confidence level. The study revealed that fish highest fertilization was recorded in 6.75g/l (82.41%) saline solution which is not significantly different (P&gt;0.05) from the result obtained in 9.0g/l (82.22%) saline solution. However, the lowest fertilization rate was observed at 0g/l (37.56%) respectively. The hatchability rate at 6.75% (63.42%) saline solution was the highest and lowest at 0g/l (23.53%) respectively. The highest survival rate was at 6.75% (54.29%) and the lowest was obtained at 0g/l (15.00%) respectively. The study concluded that saline solution had positive effect on egg fertilization, hatching rate and survival of Clarias gariepinus at different concentrations of physiological saline solution. This study recommends 6g/l physiological saline solution as an ideal concentration for optimal fertilization of eggs, hatching and subsequent survival of the larvae.