Effect of fenitrothion on reproduction of the freshwater prawn Macrobrachium lamerrii

Acute and toxic effects of fenitrothion on eggs and larvae of Macrobrachium lamerrii have been studied. The hatching success of the eggs is not affected when berried females are exposed to fenitrothion. No drastic changes in egg production are seen at sublethal levels, while at higher concentrations females abort their eggs. The first-stage larvae hatching in subacute chronic exposure are not morphologically abnormal. The rate of heart pulsation in embryos and larvae increased under pollutant stress. Larvae are highly susceptible and death rate of larvae does not increase during molt period. On chronic exposure there are drastic changes in the gonads of M. lamerrii.     

Resistance of Mexican fruit fly to quarantine treatments of high-pressure processing combined with cold

Mexican fruit fly Anastrepha ludens Loew (Diptera: Tephritidae) is one of the most important insects infesting fruits. Although high pressure has been proposed as an alternative quarantine process for this pest, conditions applied to destroy eggs and larvae can also damage the fruits. The objective of this study was to assess the biological viability of A. ludens eggs treated by high-pressure processing at 0°C, establishing whether nondestroyed eggs and larvae preserved their ability to develop and reproduce. One-, 2-, 3-, and 4-day-old eggs were pressurized at 50, 70, or 90?MPa for 0, 3, 6, or 9?min. The hatching ability of pressurized eggs and their capacity to develop larvae, pupae, and reproductive adults were evaluated. The ability of pressurized larvae to pupate was also registered. The results showed that most of the eggs that resisted the treatments were able to produce adults with capability to reproduce a new generation of A. ludens flies. Larvae were less resistant than eggs. All larvae were killed at 90?MPa for 9?min. The pressure induced the expression of heat shock proteins (HSP) in second- and third-instar larvae. The HSP showed a baroprotective effect in A. ludens larvae. These results are relevant to the industry because they show that eggs of insects infesting fruits treated by high-pressure processing were able to pupate after treatments. This indicates that efforts must be addressed to destroy all eggs because most of the surviving organisms could reach an adult stage and reproduce.     

Egg cannibalism and carnivory among three species of Toxorhynchites

In laboratory experiments, third and early fourth instar larvae of Toxorhynchites amboinensis, Tx. splendens and Tx. brevipalpis, previously starved 24 h, rapidly cannibalized eggs of their own species, or ate the eggs of other species present on the water surface in small containers. Toxorhynchites amboinensis and Tx. splendens larvae of either instar cannibalized eggs somewhat more rapidly than Tx. brevipalpis, probably because brevipalpis eggs distributed themselves around the edge of the container and were less accessible. When offered heterospecific eggs, fourth instar larvae of all three species ate them as efficiently as they cannibalized their own except that eggs of Tx. brevipalpis were eaten very slowly. Toxorhynchites amboinensis larvae were offered conspecific hatched eggs, and these also were consumed.     

Evidence for a maternal yolk factor associated with increased tolerance and resistance of feral white sucker (Catostomus commersoni) to waterborne copper

White suckers, collected from lakes containing elevated levels of copper (12 micrograms liter-1) and zinc (250 micrograms liter-1), were evaluated for reproductive performance, growth and survival of the larvae, and tolerance of the larvae to waterborne copper. Fertilization success was not impaired in white suckers from contaminated sites; metal-exposed males performed better than control males in fertilization trials with control eggs. Larvae hatched from eggs collected at contaminated sites and fertilized in clean water were smaller, developed at a slightly increased rate, and exhibited poorer growth and survival than larvae from control sites. Larvae showed significant changes in resistance and tolerance to copper with age. During the period of endogenous nutrition, larvae from eggs taken at contaminated sites showed increased resistance and tolerance to waterborne copper relative to controls. The effect was not seen in larvae at first feeding, at ages older than 4 days after the onset of feeding (25 days posthatch) or in larvae hatched from control eggs fertilized with sperm from males taken at contaminated sites. This study provides evidence for a maternal yolk factor associated with increased tolerance and resistance of larvae to copper.     

Effects of bisphenol A on the development, growth, and sex ratio of the housefly Musca domestica

The effects of bisphenol A (BPA) on the life cycle of the housefly Musca domestica were examined. The sex ratio of the imago shifted in favor of males when eggs and larvae were exposed to BPA in culture media at concentrations of 1,000 microg kg(-1) for five generations and 100 microg kg(-1) for seven generations. Notably, at an initial concentration of 100 microg kg(-1), BPA levels in the growth medium decreased 61% at 4 h after egg inoculation, and no BPA was detected after 24 h. Pupal weight increased upon exposure to 100 microg kg(-1) BPA but decreased after exposure to 1,000 microg kg(-1), suggesting highly variable concentration-dependent toxicity. Both the survival ratio of eggs to the third instar larval stage and the ratio of pupae to larvae decreased, indicating that BPA affected both eggs and larvae. A delay in the timing of emergence typically was observed in insects exposed to >100 microg kg(-1) BPA. Compared to the control group, juvenile hormones II and III levels were elevated significantly in larvae between days 4 and 7 in medium spiked with 100 microg kg(-1) BPA. These results suggest that exposure to environmentally relevant concentrations of BPA during the early stages of the housefly life cycle can result in various disorders (pupal weight and sex ratio) that may be a consequence of endocrine disruption.     

Effect of Cypermethrin on Some Developmental Stages of <Emphasis Type="Italic">Drosophila melanogaster</Emphasis>

This study investigated the effects of cypermethrin, a synthetic pyrethroid, on some developmental features of Drosophila melanogaster. Before the experiment the lethal concentration of this insecticide was determined. Cypermethrin solution was applied to Drosophila melanogaster by means of nutrition, by adding it to the culture medium. In the control group no such substance was applied. Our aim was to find out whether any developmental toxic effects occur, and, if they do, during which stage, by observing the rates of egg-laying of adult females, the development of eggs, and the development of larvae. The results showed that there was no significant difference in the rates of egg-laying. However, the decrease in the rate of egg development revealed that eggs and early embryonic stages were sensitive to toxic effects. The same toxic effect was not observed in third instar larvae. The toxic effect was observed to be strongest in the early stages of development.     

Vertical transmission of St. Louis encephalitis virus to autogenously developed eggs of Aedes atropalpus mosquitoes

Vertical transmission of St. Louis encephalitis virus was demonstrated by a strain of Aedes atropalpus mosquitoes from Garrett County, MD. Five-day-old parental females containing fully formed autogenous eggs were infected by intrathoracic inoculation. St. Louis encephalitis virus was detected in batches of fertilized eggs and fourth instar larvae. Estimated filial infection rates of approximately 1% were observed for both eggs and larvae.     

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 benzo(a)pyrene on early development of flatfish

The ontogenetic effects of the environmental carcinogen benzo(a)pyrene (BAP) on three species of larval flatfish were investigated using concentrations (from 0.10 to 4.2 ppb) which were comparable to levels found in polluted harbors. BAP-treated sand sole (Psettichthys melanostichus) eggs displayed a significant decline in hatching success and a significantly higher incidence of developmental anomalies than did control eggs. Flathead sole (Hippoglossoides elassodon) eggs exposed to a single dose of a water-soluble BAP-bovine serum albumin complex demonstrated evidence of toxie injury with pycnotic nuclei present in the integument and, more commonly, in ocular and neural tissues. An increased incidence of morphological anomalies in English sole (Parophyrs vetulus) eggs and larvae exposed to BAP was not detected.     

淡色库蚊卵期静电场处理对其生命系统影响的初步研究

笔者以静电场为实验电场，以淡色库蚊（Ｃｕｌｅｘｐｉｐｉｅｎｓｐａｌｌｅｎｓ）的卵为处理对象，测定不同电场强度和处理时间对该蚊虫生物学特性的影响。研究结果提示：该蚊卵经静电场处理后，明显地改变了蚊虫胚后发育的各种特性；在１００ＫＶ／ｍ２固定场强下，９０ｍｉｎ处理后的幼虫存活率仅为０．５８．发育为成蚊后，其所产的卵块中约７０％左右的卵为未受精卵；在３０ｍｉｎ固定处理时间下，５０ＫＶ／ｍ２场强处理对蚊虫各项特性有利，而较高的场强则会起抑制作用；静电场的处理也明显增加了个体发育的差异，处理过的幼虫完成发育的时间要比未处理过的迟１～４天     

Effects of Diazinon on Mummichog (<Emphasis Type="Italic">Fundulus heteroclitus</Emphasis>) Larvae Produced from Eggs Differentially Treated with PCB126

During their formation, fish eggs receive a load of contaminants including polychlorinated biphenyls (PCBs) from their mother and then, after spawning, are exposed to pesticides present in water. This is the first study investigating the interaction between PCBs and organophosphorous pesticides in fish. The effect of diazinon was evaluated in mummichog (Fundulus heteroclitus) larvae produced from eggs differentially treated with 3,3′,4,4′,5 pentachlorobiphenyl (PCB126). A few hours after fertilization, eggs were treated topically with a solution of PCB126 (100 pg/μl) in dimethyl sulfoxide (DMSO) (Group P), DMSO (Group D), or not treated (Group N). Newly hatched larvae from Groups P and D were exposed to diazinon (125–12,900 ng/L) in saltwater and Group N larvae to saltwater alone. Diazinon caused a dose-responsive inhibition of cholinesterase (ChE) activity at environmentally realistic concentrations (≥361 ng/L), with up to 85% inhibition at 12,900 ng/L. Body length was also inversely related to diazinon at concentrations ≥361 ng/L and was significantly reduced (by 4%) at 12,900 ng/L compared to controls. Mummichog larvae were highly sensitive to PCB126 with an eightfold induction of the activity of ethoxyresorufin-O-deethylase at a dose of 710 pg PCB126 or 3.6 pg TCDD-TEQ/g wet weight. Treatment with PCB126 also caused a slight reduction in body length but no effect on ChE activity. This study indicates that the effects of PCB126 and diazinon on body length are cumulative because no significant synergistic or antagonistic interactions were observed. Longer term studies with several doses of PCB126 are needed to fully assess the overall impact of joint exposure to diazinon and PCB126 on growth and survival of fish larvae.     

黄足真蚋孳生习性和幼虫龄期的观察

该文报道黄足真蚋幼期的孳生习性及幼虫龄期组成。卵全部在０．３～３ｃｍ深的水中漂浮的茅草叶上采获，在石块和砖头、塑料等杂物上未查到卵。在茅草叶、石块和杂物上共采获７２８条幼虫，茅草叶、石块和杂物上的幼虫数分别占幼虫总数的５７．１％、３５．３％和７．６％。共采获２１７只蛹，茅草叶上蛹数占采蛹总数的７８．３％，石块上仅占２１．７％，在杂物上未来到。黄足真蚋幼虫分为５个龄期，来到１～３龄幼虫较少，４～５龄较多，占幼虫总数的８１．２％，大部分幼虫已为成熟幼虫。     

Efficacy of Australian quarantine procedures against the mosquito Aedes aegypti

Methods employed by Australian quarantine officers to control Aedes mosquitoes in containers were tested against all stages of Aedes aegypti. Saltwater emersion killed all larvae but not pupae or eggs that were briefly exposed. Swimming pool chlorine, methyl bromide fumigation, and permethrin (2% active ingredient) spray provided 100% mortality of eggs, larvae, and pupae. Aerosol sprays incorporating synthetic pyrethrins are practical and also provide effective control of adults.     

一种水生昆虫采样器的研制与应用

目的 研制一种水生昆虫卵、幼虫、蛹的采集装置,并应用于实际工作.方法 基于负压原理,研制水生昆虫卵、幼虫、蛹的采集装置,主要部件包括连续收集瓶、吸蚊管等.结果 成功研制了水生昆虫卵、幼虫、蛹采集器,由手柄、连续采集管、负压系统组成.采样器尺寸:45 cm×12 cm×6 cm,重量350 g,电池电压12 V,连续工作...     

Platanna (Xenopus laevis) as a test organism for determining the embryotoxic effects of environmental chemicals

It has been successfully demonstrated that platanna (Xenopus laevis) allows the artificial induction of spawning at any time during the year. The number of eggs collected from a female ranged between 500 and 2400, the fertilization rate varying between 10 and 85%. When unaffected by chemicals, the embryonic development of the larvae took between 8 and 30 weeks. Di(2-ethylhexyl) phthalate (DEHP), methylmercury chloride, and the thalidomide analog EM 12 were used for the experiments described. DEHP at a concentration of 2 ppm retarded the development of the larvae and caused reduced pigmentation of the tadpoles. Methylmercury chloride has been found to have teratogenic and embryolethal effects at a concentration as low as 0.01 ppm. The following teratogenic effects have been determined: bent tails of the larvae, retarded development of the filter system, disturbed osmotic regulation, deranged positional and spatial orientation. EM 12 has been proven to have embryolethal effects at concentrations around 100 ppm. At lower concentrations this substance has teratogenic effects, i.e., it interferes in various ways with the development of the limbs.     

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。     

Influence of larval period on responses of overwintering green frog (Rana clamitans) larvae exposed to contaminated sediments

Pond-breeding amphibians exhibit large intra- and interspecific differences in the duration of the aquatic larval phase. In contaminated aquatic environments, a prolonged larval phase means prolonged exposure to pollutants and, potentially, more severe toxic effects. In the laboratory, we tested this hypothesis by exposing green frog larvae (Rana clamitans) to commercial clean sand (control), sediment from an abandoned surface mine (mine), or sediment contaminated with coal combustion waste (CCW). By collecting eggs late in the breeding season, we obligated larvae to overwinter and spend a protracted amount of time exposed to contaminated sediments. The experiment was continued until all larvae either successfully completed metamorphosis or died (301 d). Larvae exposed to mine sediments accumulated significant levels of Pb and Zn, whereas larvae exposed to CCW-contaminated sediment accumulated significant levels of As, Se, Sr, and V. Larvae exposed to mine sediments suffered sublethal effects in the form of reduced growth and size at metamorphosis, but the proportion of larvae successfully completing metamorphosis (93%) was the same for both control and mine treatments. In contrast, larvae exposed to CCW-contaminated sediment suffered greatly reduced survival (13%) compared to both control and mine treatments. Moreover, among larvae in the CCW treatment, the majority of mortality occurred during the latter part the overwintering period (after day 205), corresponding to the onset of metamorphosis in the controls. Our results suggest that the length of the larval period may be one of many life-history or ecological characteristics that influence the sensitivity of aquatic breeding amphibians to environmental pollutants.     

Laboratory determination of efficacy of a Santalum spicatum extract for mosquito control

The activity of QN50, a sequiterpene alcohol derived from Australian sandalwood (Santalum spicatum), was tested for its effectiveness against larvae of 2 mosquito species (Culex molestus and Aedes camptorhynchus [Diptera: Culicidael), nymphs of 2 species of water boatmen (Micronecta robusta and Agraptocorixa [Hemiptera: Corixidae]), immature Daphnia sp. (Crustacea), and mosquito eggs (Cx. molestus). In a series of laboratory bioassays, field-collected mosquito larvae, eggs, and immature corixids and daphnids were placed in beakers with either QN50, methoprene or source water only (control). The mosquito larvae exposed to QN50 had reduced survivorship and average longevity relative to the control and to methoprene at most concentrations used in this study. The hatching rate of mosquito eggs was unaffected by methoprene or QN50. Corixid nymphs and daphnids experienced high mortality in both methoprene and QN50 relative to the control, but there was no difference in the effect between the compounds. The results of this preliminary study suggest that further research into the mode of action and efficacy of QN50 as a potential alternative to methoprene for mosquito abatement is warranted.     

Importation of Aedes albopictus and other exotic mosquito species into the United States in used tires from Asia

Between May 18 and December 4, 1986, 79 seagoing containers and their contents of 22,051 used tires were inspected for adult mosquitoes as well as eggs and larvae. Of the total inspected, 5,507 tires (25%) contained significant amounts of water. No adults or eggs were found. Fifteen tires contained mosquito larvae that were identified as Ae. albopictus, Ae. togoi, Culex pipiens complex, Tripteroides bambusa and Uranotaenia bimaculata. The infestation rate for all species was 6.8 infested tires per 10,000 tires (wet and dry) inspected. Aedes albopictus larvae were most frequently collected, occurring at a rate of 20 infested wet tires per 10,000 inspected.     

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.