Effects of copper on hatching of larvae and prezoea survival of Petrolisthes galathinus (Porcellanidae): assays with ovigerous females and isolated eggs

Ovigerous females of the porcellanid crab Petrolisthes galathinus were selected for toxicological bioassays. A first assay was made on isolated eggs, exposing them to 0 (control), 0.5, or 1 mgL(-1) copper. Both copper concentrations caused significant mortality just before hatching. The few prezoeas hatched at 0.5 and 1 mgL(-1) were unable to reach the zoea stage. A second assay was conducted on the ovigerous females isolated and exposed to 0 or 0.1 mgL(-1) copper. Females were checked daily and the percentages of mortality, egg loss, and hatching larvae were recorded. No differences in either mortality of females or number of hatched larvae were noted between control and copper-exposed groups. From each of these groups, 15 recently hatched prezoeas were transferred to clean seawater, while another 15 were exposed to 0.1 mgL(-1) copper. The numbers of dead or alive prezoeas, transitional larvae, and zoeas were ascertained every 24 h. Prezoeas hatched from exposed eggs and transferred to clean seawater at hatching showed enhanced mortality and a delay in development, compared with control larvae maintained in clean water throughout. Copper at 0.1 mgL(-1) was lethal to almost all larvae exposed only after hatching, while those that had also been preexposed to copper during embryonic development showed a certain degree of tolerance to copper exposure, at least during the first 24 h after hatching.     

The effects of selected rice and soybean pesticides on the eggs of Psorophora columbiae

Twenty-five pesticides used in the production of rice and soybeans in Texas were tested in the laboratory to determine their toxicity to the eggs of Psorophora columbiae. A reduction in hatching rate occurred when eggs were treated with a herbicide formulation containing thiobencarb and with one containing a tank mixture of propanil and molinate. A carbaryl formulation induced hatching of eggs prior to their exposure to the hatching stimulus. Reduced survival to second instar of larvae hatching from treated eggs was observed with insecticide formulations of acephate, carbofuran, malathion, methyl parathion and toxaphene; a fungicide formulation of triphenyltin hydroxide and the tank mixture of the herbicides, propanil and molinate.     

Short-term test for predicting the potential of xenobiotics to impair reproductive success in fish

Short-term screening tests with the zebra fish (Brachydanio rerio) have been developed for predicting the potential of xenobiotics to impair reproductive success in fish. The aim was to find simple and sensitive test parameters and to simulate exposure situations typical for anadromous fish species (salmonids), which generally cross heavily polluted coastal areas or estuaries before they reach uncontaminated upstream spawning areas. Therefore, particular attention was directed to tests designed to assess adverse effects induced during gametogenesis in adult fish. the test protocol involves exposure of adults prior to, but not during, spawning and the effects are measured in the offspring as alterations in hatching frequency and hatching rate of eggs, and survival and stress tolerance of embryos and larvae. Some representative examples of the application of these tests are given, and it is shown that impairment of reproductive success can be induced by exposure of parent fish prior to spawning at concentrations of xenobiotics at least five times lower than those yielding effects during direct exposure of embryos and larvae. It is suggested that, in hazard assessment programs, tests of the effect of xenobiotics on the offspring of preexposed adults be routinely incorporated.     

Effects of sublethal dosages of insecticides on Culex quinquefasciatus

Groups of Culex quinquefasciatus were exposed as fourth instar larvae to sublethal concentrations (0.1 LC50 and LC50) of malathion, methoprene, propoxur or resmethrin. Females exposed as larvae to an LC50 level of methoprene had reduced wing length and longevity. Egg production was reduced by 50% and 39% in those mosquitoes exposed to LC50 levels of malathion or methoprene, respectively. In contrast, egg production and egg raft size increased following treatment with 0.1 LC50 levels of malathion or methoprene. Females exposed as larvae to methoprene laid 30% fewer eggs per raft, and egg hatching decreased 36% compared with controls. Females exposed as larvae to LC50 levels of malathion or methoprene laid shorter eggs than controls. The proportion of females in the adult population was reduced following exposure to either propoxur or resmethrin, and increased following exposure to malathion. Time to pupation and time of emergence of the adult populations were increased following exposure to most of the insecticidal treatments. These results indicated that a single, sublethal exposure to certain insecticides had a significant effect on mosquito reproduction.     

The effects of moisture on ovipositional responses and larval eclosion of Aedes albopictus

Moisture plays a major role in the dynamics of mosquito populations, especially those breeding in container habitats. Despite this importance, the role of moisture conditions as they affect oviposition and egg development in Aedes vectors remains largely unexplored. We investigated the effect of exposing gravid female Aedes albopictus mosquitoes and their eggs to different moisture levels (MLs) for various periods on oviposition and hatching. Overall, high-moisture substrates (HMSs; 66% and 72%) provided better environments for egg laying. The timing of initial egg laying was far longer at the lowest substrate moisture level (LSML, 25% and 41.2%) than at HMSs. The numbers of eggs laid were much lower in the drier environments. At LSMLs, gravid females retained increasing numbers of mature eggs until death, and egg retention decreased gradually with increasing ML. The HMSs also provided better environments for larval eclosion. The numbers of eggs hatched were lower at the LSML than the HSML environment. No egg hatching occurred after 1 h exposure to moisture. However, egg hatching occurred by installment, with spontaneous hatching (SH) increasing gradually with increasing ML. High-moisture conditions combined with long exposure (30 h and 48 h) favored SH. These results suggest that Ae. albopictus females can respond to better moisture conditions for increased success of embryonation and larval eclosion. This information may be useful in the colonization of floodwater Aedes species.     

石灰水对埃及伊蚊不同发育阶段影响研究

目的通过石灰水对埃及伊蚊生活史幼期不同阶段生长发育影响的实验室研究,评价生石灰对防治埃及伊蚊的干预效果,为生石灰用于埃及伊蚊的防治提供实验数据。方法将一定数量的埃及伊蚊依据不同发育阶段(卵、Ⅰ~Ⅳ龄期蚊幼、蛹)分别饲养于石灰水中,观察蚊幼活动情况,记录不同时期相应孵化时间、孵化率和死亡率,同时将实验室过夜自来水(实验室脱氯水)饲养蚊虫作对照,分析比较不同饲养环境、不同发育阶段埃及伊蚊发育的变化差异。结果对照组埃及伊蚊卵的平均孵化时间为1.75 d,而试验组(1.3 g/L石灰水饲养)埃及伊蚊卵的平均孵化时间为3.84 d,是对照组的2.19倍,孵化时间的差异具有统计学意义(t=36.02,P<0.05)。试验组埃及伊蚊卵孵化率为59.3%,对照组为89.3%,两组之间孵化率的差异具有统计学意义(χ^(2)=35.38,P<0.05)。Ⅰ~Ⅳ龄试验组蚊幼死亡率分别为44.0%、92.0%、97.3%、98.7%,显著高于对照组蚊幼死亡率,两组之间死亡率的差异具有统计学意义(χ^(2)值为65.79~276.53,P<0.05)。试验组蛹的死亡率为98.7%,显著高于对照组的死亡率,两组之间死亡率的差异具有统计学意义(χ^(2)=280.35,P<0.05)。对照组埃及伊蚊卵、蚊幼和蛹的死亡率分别为10.7%、2.3%和2.0%,三组之间死亡率的差异具有统计学意义(χ^(2)=25.09,P<0.05)。对照组埃及伊蚊卵的死亡率明显高于蚊幼和蛹。试验组埃及伊蚊卵、蚊幼和蛹的死亡率分别为40.7%、83.0%和98.7%,三组之间死亡率差异具有统计学意义(χ^(2)=170.88,P<0.05)。结论石灰水对埃及伊蚊不同发育阶段均具有明显抑制作用,对蛹的杀灭作用最大,其次是蚊幼和卵。随着埃及伊蚊幼虫年龄的增长,石灰水对其抑制效果逐渐增强。但生石灰对埃及伊蚊成蚊的防治效果有待进一步的现场验证。     

Effects of triphenyltin acetate on survival, hatching success, and liver ultrastructure of early life stages of zebrafish (Danio rerio).

In order to evaluate the toxicity of the fungicide triphenyltin acetate (TPTA) on hatching, survival, morphology, and histology of early life stages of zebrafish (Danio rerio), newly fertilized eggs were exposed to concentrations of 0.5, 5, 25, 75, and 100 microg/liter TPTA for 96 h at 28+/-0.5 degrees C. Embryos and larvae were kept under constant observation for up to 7 days and studied with respect to mortality and teratogenic effects as well as histological and cytological alterations in the liver as endpoints of sublethal toxicity of TPTA. Exposure to TPTA caused dose- and time-related effects with respect to all parameters investigated: (1) Hatching was delayed at concentrations >/=0.5 microg/liter TPTA; (2) mortality increased at >/=25 microg/liter TA after 96 h exposure, with TPTA toxicity being higher in larval than in embryonic stages; (3) from >/=25 microg/liter, larvae exhibited skeletal malformation, retarded yolk sac resorption, and edema in the heart and yolk sac regions; and (4) histo- and cytopathological alterations of larval liver included changes in nuclei and mitochondria as well as glycogen depletion from >/=0.5 microg/liter TPTA. The study thus demonstrates not only an elevated sensitivity of zebrafish embryos to TPTA in stages prior to hatching, but also the importance of continuous observation over extended periods after termination of the actual exposure for a comprehensive evaluation of the toxicity of chemical compounds.     

Toxicity of methylmercury,mercuric chloride,and lead in killifish (Fundulus heteroclitus) from Southampton,New York

We have previously found great differences in susceptibility to teratogenic effects of methylmercury (meHg) among batches of eggs produced by different females of Fundulus heteroclitus. In the present study we investigated the relationships of resistance to meHg by a batch of eggs with other parameters of resistance. There was a positive correlation between embryonic meHg resistance and HgCl₂ resistance, although HgCl₂ generally caused less severe defects at a given dose level. The batches that were more susceptible to meHg had a greater uptake of mercury than the more resistant batches. There was a negative correlation of meHg resistance and Pb resistance (as measured by a skeletal index hatching), however. There was a positive correlation of meHg resistance of embryos and the subsequent meHg resistance of larvae after hatching.     

Hatching success and survival of fish early life stages in a chronic exposure to nevirapine: a case study of the Mozambique tilapia

The anti-retroviral nevirapine has been detected in surface waters throughout South Africa and its effects on non-target aquatic animals are still unknown. The aim was to investigate the potential effects of nevirapine on the hatching success and survival of Oreochromis mossambicus early life stages through a chronic exposure. The exposer started with newly fertilized O. mossambicus eggs and concluded 30 days after hatching. Environmental relevant concentration of nevirapine (1.48 µg/l) was used in a static renewal system and a controlled environment (27 ± 1°C; 14:10 day/night cycle). The main endpoints assessed included hatching success and survival; a morphological assessment was also done on whole individual on day 1 and 30 post-hatching to identify any physical abnormality. Nevirapine had no noticeable effects on the hatching success and survival of O. mossambicus larvae; no statistically significant differences were observed between the control and the nevirapine exposed fish (p > 0.05).     

Developmental,behavioral, and reproductive effects experienced by Japanese medaka (Oryzias latipes) in response to short-term exposure to endosulfan

Japanese medaka (Oryzias latipes) were exposed to concentrations of 0.01, 0.10, and 1.0 microg/L of the pesticide endosulfan for 24h beginning either 4-6h postfertilization or 4-6h posthatch to determine effects on hatching time, growth, mobility, foraging ability, and reproduction. Eggs exposed to endosulfan took longer to hatch, and the resulting fry were smaller at 1 week of age and had decreased mobility at 2 weeks of age. Upon reaching sexual maturity, these individuals also produced fewer eggs, and these eggs took significantly longer to hatch. Medaka exposed to endosulfan shortly after hatching did not differ in early mobility or foraging ability. Interestingly, upon reaching sexual maturity, these individuals produced more eggs than did unexposed females. The observed effects were not dose-dependent, with medaka exposed to intermediate concentrations of endosulfan (0.10 microg/L) exhibiting the greatest response. These results suggest that short-term exposure to environmentally relevant concentrations of a common pesticide may have long-term effects on growth, behavior, and reproduction in fish.     

In ovo exposure to polychlorinated biphenyls: reproductive effects on second-generation American kestrels

The reproductive success of wild birds has been affected by exposure to multiple contaminants. Reproduction of captive American kestrels (Falco sparverius) was suppressed when adult birds were exposed to dietary polychlorinated biphenyls (PCBs). In this study, the reproductive effects of in ovo exposure to PCBs is explored, along with determining effects on reproduction in second-generation birds indirectly exposed to PCBs. Reproductive changes in this subsequent generation are examined separately in male and female birds. Captive American kestrels (F. sparverius) were hatched from clutches with eggs containing environmentally relevant levels of total PCBs (34.0 μg/g whole egg WW versus 0 μg/g controls); parent birds had been fed PCB-spiked (Aroclor 1248:1254:1260) food (7 mg/kg BW day⁻¹) for 100 days until their eggs hatched. In 1999, the second-generation PCB birds were paired with unexposed kestrels having reproductive experience. In ovo PCB exposure suppressed egg laying completely in 25% of PCB females and resulted in delays in clutch initiation and smaller clutch sizes for PCB male and female pairs. There was no evidence in this study of in ovo PCB treatment effects on fertility or hatching success. The decline in reproductive success was also reflected in the reduced fledging success and higher incidence of complete brood mortality of PCB nestlings. Differences between in ovo–exposed PCB males and females but not between controls were evident in reproductive success. In ovo PCB exposure appears to have had greater effects on female kestrels until clutch completion, with a greater time lag between pairing and egg laying, reduced numbers of pairs laying eggs, and smaller clutches being laid. In ovo PCB exposure has greater effects later in the breeding season on male kestrels, which had poorer hatching and fledging success relative to the PCB females. Possible behavioral and physiological mechanisms involved in these reproductive changes are discussed. Received: 25 July 2000/Accepted: 8 December 2000     

Toxicity of 4-chloroaniline in early life-stages of zebrafish (Brachydanio rerio): I. Cytopathology of liver and kidney after microinjection

In addition to survival and hatching parameters, cytological alterations in liver and kidney of 4- and 6-d old zebrafish larvae (Brachydanio rerio) following single microinjection of fertilized eggs at the germ-ring stage with 5, 12.5, and 25 ng 4-chloroaniline/egg were investigated by means of electron microscopy. Whereas survival remained unaffected, microinjection with 4-chloroaniline disturbed hatching of larvae. Hatching was delayed by microinjection of 12.5 ng 4-chloroaniline/egg and above when compared to controls. Cytological investigations revealed ultrastructural changes in both liver and kidney in a dose- and time-dependent fashion. In the liver, major cytopathological changes included fenestration, fragmentation, and vesiculation of the rough endoplasmic reticulum, proliferation of atypical mitochondria, and atypical lysosomes. Furthermore, myelin whorls, lipid inclusions, and cholesterol crystals were increased, whereas glycogen stores were reduced. Renal tubular cells displayed altered brush borders, proliferation of nucleoli, atypical mitochondria, fenestrated, fragmented, and vesiculated RER cisternae, as well as giant lysosomes. Most of these effects indicate cellular dysfunction (e.g., disturbance of lipid metabolism in the liver), whereas others illustrate general cellular stress-responses to chemical aggression. Comparisons of results with those of previous studies based on conventional fish exposure prove the suitability and sensitivity of microinjection bioassays with zebrafish eggs as an alternative to conventional early life-stage tests.     

Effects of chronic copper exposure on development and survival in the southern leopard frog (Lithobates [Rana] sphenocephalus)

Exposure to environmental contaminants contributes to the global decline of amphibian populations. The impacts of organic contaminants on amphibians are well documented. However, substantially less is known concerning the potential effects of metals on amphibian populations. Copper (Cu) is an essential element, but it can be toxic at concentrations only slightly higher than the normal physiological range. The present study examines the effects of chronic Cu exposure on embryos and larvae of southern leopard frogs, Lithobates (Rana) sphenocephalus. Groups of eggs from multiple clutches were collected from two wetlands and exposed to a range of Cu concentrations (0-150 μg/L) until they reached the free-swimming stage, and then individual larvae were reared to metamorphosis. Higher Cu concentrations significantly reduced embryo survival to the free-swimming stage but did not further reduce survival to metamorphosis. Larval period was affected by Cu treatment, but the clutch from which larvae originated (i.e., parentage) explained a higher proportion of the variation. Embryo survival to hatching varied significantly among clutches, ranging from 42.9 to 79.2%. Measurable levels of Cu were found in larvae with body burdens up to 595 μg Cu/g dry mass in the 100 μg/L treatment, and larval Cu body burdens were higher than in metamorphs. The present study also demonstrated that higher initial egg density ameliorated embryo mortality at higher Cu levels and should be accounted for in future studies.     

Effects of an organophosphorous insecticide on survival, fecundity, and development of Hylyphantes graminicola (Sundevall) (Araneae: Linyphiidae)

Abstract-The effects of an organophosphorous insecticide, methamidophos, on fecundity and development of the spider Hylyphantes graminicola (Sundevall) (Araneae: Linyphiidae) were assessed under laboratory conditions. Susceptibility of adults of both sexes to the insecticide and its influence on fecundity of females and development of offspring were investigated. At 48 h after topical application in adults, the median lethal dose (LD50) and 10% lethal dose (LD10) were 0.35 and 0.12 microg/spider, respectively, for males and 0.52 and 0.16 microg/spider, respectively, for females. Methamidophos had detrimental effects on fecundity of females; number of eggs per clutch, total egg mass, and clutch size decreased significantly. The hatching rate of eggs from LD10-treated females was slightly higher than the rate in the controls, but the hatching rate of eggs from LD50-treated females was lower than the rate in the controls. However, no significant differences were observed in hatching time and development time across treatments. Development time of spiderlings from LD50-treated females was significantly longer than the time in the controls, and body sizes of the first spiderlings from insecticide-treated females were larger than those in the controls. However, matured offspring were smaller than those in the controls. It was concluded that methamidophos has long-term effects on H. graminicola, and that this may affect the development of spider populations in the field.     

Egg hatching of Aedes mosquitoes during successive floodings in a Rift Valley fever endemic area in Kenya

Floodwater Aedes breeding habitats in central Kenya were sequentially flooded to determine the numbers of mosquito eggs hatching during each flooding. Approximately 90% of the larvae sampled during 4 floodings emerged during the initial flooding. The number of Aedes eggs hatching during the second flooding was lowest of all 4 floodings, and no significant differences in the amount of egg hatching during floodings 3 and 4 were seen. Unhatched Aedes eggs were present in soil samples collected after the final flooding. The possible implications of these findings with regard to Rift Valley fever virus control are discussed.     

The spiny-cheek crayfish Orconectes limosus (Rafinesque, 1817) as an inhabitant of the Baltic Sea — experimental evidences for its invasion of brackish waters

The main aim of the present study was to determine the effect of low salinity conditions (3 PSU and 7 PSU) on the hatching success, growth and mortality of Orconectes limosus. The results revealed that berried females survived exposure to salinities of 3 PSU and 7 PSU whilst incubating their eggs. The reproductive success reached 100% at both salinities. The length increment of young crayfish per molt was larger at 7 PSU than at 3 PSU — but their condition was affected by higher salinity. The mortality among juveniles reached approximately 50% within 5 weeks of hatching at both salinities.     

Insecticidal effect of aliphatic alcohols against aquatic stages of Aedes mosquitoes

Effectiveness of certain long carbon chain aliphatic alcohols as ovicides and larvicides was investigated under laboratory conditions against eggs and larvae of Aedes aegypti and Aedes scutellaris. Out of the eight alcohols tested, three (1-decanol, 1-undecanol and 1-dodecanol) proved to be very effective. The hatching of mosquito eggs was inhibited at a dosage of 5 to 7 litres/hectare. First, third and fourth instar larvae were killed at a dosage of 3 to 7 litres/hectare. First instar larvae were more sensitive to the alcohols than the older larvae. The shorter carbon chain alcohols (2-mercapto-ethanol, 1-butanol, benzyl alcohol and 2-octanol) proved unsatisfactory due to their volatility and solubility. Longer carbon chain alcohols (1-tetradecanol, 1-hexadecanol and 1-octadecanol), which are solid and wax-like at room temperature, proved unsatisfactory when dissolved in hexane and applied to eggs and larvae.     

Effects of Photofrin II on adults of Eretmapodites quinquevittatus

This research was conducted to further assess the efficacy of photosensitizers as adult mosquito control agents. Fourth-stage larvae of Eretmapodites quinquevittatus were fed Photofrin porfimer sodium (PII) (< or = 3.75 microg/ml) and the resulting adults (parentals) were photoirradiated. These parentals were mated with untreated controls and resulting 1st generation (F1) progeny were inbred. Comparisons of fecundity and fertility were made between parentals and resulting F1 progeny. Interbred F1 adults survived significantly longer than parentals (P > 0.05). Parental females laid fewer eggs than F1 females, and parental eggs hatched at a significantly lower rate than eggs of F1 females (P < 0.01). Neither PII nor any effects of PII seem to be transferred from parent to offspring. Reduced fecundity and fertility may be due to reduced energy levels caused by exposure to PII. Experimental adults fed PII exhibited significantly reduced survivorship when compared to untreated controls (P < 0.001). Fertility did not differ when compared to controls, but experimental adult fecundity was significantly less than control fecundity for the constant photoirradiation group.     

Ingestion of petroleum by breeding mallard ducks: Some effects on neonatal progeny

Breeding female mallard ducks consuming petroleum-contaminated food show significant induced increases in the naphthalene-metabolizing properties of microsomes prepared from their livers. Food contaminated with South Louisiana crude oil was more potent than food contaminated with similar concentrations of Prudhoe Bay crude oil and in each instance food contaminated with 3% (v/w) induced greater increases than food contaminated at the 1% level. These increases in hepatic naphthalene-metabolizing activity may reflect their responses to circulating petroleum contaminants derived from ingested crude oil. When incubated, fertilized eggs laid by the females consuming South Louisiana crude oil yielded ducklings that upon emergence possessed high levels of naphthalene-metabolizing activity associated with hepatic microsomes. In contrast, ducklings derived from eggs laid by females consuming food contaminated with Prudhoe Bay crude oil showed no increases in total hepatic naphthalene-metabolizing activity and only those ducklings hatched from eggs laid by females consuming food contaminated with 3% crude oil showed significantly induced levels of specific naphthalene-metabolizing activity at hatching. During the first week of postnatal life both the uncontaminated ducklings and the ducklings hatched from eggs laid by females consuming food contaminated with South Louisiana crude oil showed initial transient rises in specific and total hepatic naphthalene-metabolizing activity. In each instance, these rises were proportional to the level of contamination in the food consumed by the females. Thereafter, the specific activities of the naphthalene-metabolizing enzyme in all ducklings declined to the level found at hatching in uncontaminated ducklings. Similarly, the total hepatic naphthalene-metabolizing activities in ducklings derived from females consuming food contaminated with 3% crude oil also declined to the level at hatching in uncontaminated ducklings. In contrast, after one week, ducklings hatched from eggs laid by females consuming food contaminated with 1% crude oil showed total hepatic naphthalene-metabolizing activities that were more than twice those found at hatching.