异噻唑啉酮类杀菌剂对黑斑蛙胚胎和蝌蚪的急性毒性

异噻唑啉酮类杀菌剂1,2-苯并异噻唑-3-酮（BIT）和甲基异噻唑啉酮（MIT）虽已在多种行业中广泛使用,但目前有关其毒性尤其对水体中生物毒性的数据还较少。鉴于BIT和 MIT在水体中普遍存在,本文研究了这两种污染物对两栖动物黑斑蛙胚胎和蝌蚪的急性毒性。黑斑蛙胚胎和蝌蚪分别暴露系列浓度的BIT和 MIT,观察化学品对其生长、发育和运动的影响,计算96小时半数致死浓度（96 h-LC₅₀）和96小时半数致畸浓度（96 h-TC₅₀）,确定最小生长抑制浓度（MCIG）。结果发现,BIT对黑斑蛙胚胎的96 h-LC₅₀和96 h-TC₅₀分别为2.99 mg?L^-1和0.60 mg?L^-1,MCIG小于0.40 mg?L^-1,对蝌蚪的96 h-LC₅₀为6.44 mg?L^-1。MIT对黑斑蛙胚胎的96 h-LC₅₀和96 h-TC₅₀分别为5.30 mg?L^-1和2.36 mg?L^-1,MCIG为2.59 mg?L^-1,对蝌蚪的96 h-LC₅₀为7.58 mg?L^-1。根据《化学农药环境安全评价准则报批稿》中两栖动物蝌蚪急性毒性的分级标准,判定BIT和MIT的毒性等级为中等。该毒性数据为异噻唑啉酮类杀菌剂的环境管理提供参考。     

Herbicide exposure affects the chemical recognition of a non native predator in common toad tadpoles (<Emphasis Type="Italic">Bufo bufo</Emphasis>)

Summary. In amphibians and fishes, evidence is increasing that chemical cues from injured conspecifics can play a role in the chemical labelling and learned recognition of unfamiliar predators. In this laboratory study, we tested the prediction that prior chemical exposure to a non-native predator feeding on conspecific tadpoles will subsequently allow tadpoles of the common toad (Bufo bufo) to recognize the chemical cues specifically released by this starved predator. Furthermore, we investigated the vulnerability of this chemically-mediated process to herbicide contamination. With these aims in view, groups of tadpoles were kept either unexposed or exposed for ten days to chemical cues from Turkish crayfish (Astacus leptodactylus) previously fed on tadpoles, both in uncontaminated water and in the presence of four sublethal concentrations of amitrole (0.01, 0.1, 1 and 10 mg.l⁻¹). We then assessed the effects of the six conditioning treatments on general activity and behavioural response to chemical cues from starved crayfish. Larval treatments did not affect the general activity of the tadpoles. By contrast, the treatments had significant effects on the behavioural response to the test solution prepared form starved crayfish. The only tadpoles to show an antipredator behavioural response to the chemical stimulation from starved crayfish belonged to the groups derived from chemical exposure to tadpole-fed crayfish in uncontaminated water and in contaminated water with the lowest concentration of amitrole (0.01 mg.l⁻¹). Conversely, this chemical stimulation produced no behavioural change in the control group or in the groups derived from exposure to tadpole-fed crayfish in contaminated water containing 0.1, 1 and 10 mg.l⁻¹ of amitrole. This study demonstrates that chemical cues released during the predator’s feeding activity can subsequently be used by common toad tadpoles in the recognition of an unfamiliar predator. In addition, our results show that the presence of sublethal amitrole concentrations can impair this recognition process. Such a pesticide effect might be especially detrimental for amphibian populations threatened by invasive predators.     

敌百虫对中国林蛙蝌蚪生长发育的毒性效应

为评价水域环境中敌百虫(trichlorfon)污染对两栖类幼体的急性毒性,将中国林蛙(Rana chensinensis)28～29期(Gos-ner)蝌蚪分别暴露于10～30 mg· L-1敌百虫5个不同浓度的水体中,分别在24、48、72和96 h统计蝌蚪的死亡率,计算半致死浓度(LC50).结果显示,暴露24、48、72和96 h,敌百虫对蝌蚪的LC50分别为14250±3.23、49.19±128、25.68±2.04、1555±1.93 mg·L-1,安全浓度(SC)为156±0.19 mg· L-1.蝌蚪中毒后尾部多呈弯曲状,仰翻,外观浮肿.对死亡蝌蚪的解剖表明,其鳃腔内充水,内鳃萎缩,肝脏、肠管和肾脏呈灰白色.另外,将28～29期蝌蚪分别暴露于0.2 ～ 2.0 mg·L-1敌百虫4个不同浓度的水体中进行慢性暴露实验,检测蝌蚪暴露28和42 d时的体重和体长以及75％个体变态所需的时间.结果表明,蝌蚪在低剂量敌百虫水体中持续暴露,其生长发育受到明显抑制,并可导致蝌蚪身体扭曲、尾部强直性弯曲等畸型发生,蝌蚪的死亡率显著增高,作用强度呈现剂量和时间的累积效应.慢性暴露实验证明SC以下的敌百虫水体仍威胁着蝌蚪的生存.     

异噻唑啉酮类杀菌剂对黑斑蛙胚胎和蝌蚪的急性毒性

异噻唑啉酮类杀菌剂1,2-苯并异噻唑-3-酮（BIT）和甲基异噻唑啉酮（MIT）虽已在多种行业中广泛使用,但目前有关其毒性尤其对水体中生物毒性的数据还较少。鉴于BIT和 MIT在水体中普遍存在,本文研究了这两种污染物对两栖动物黑斑蛙胚胎和蝌蚪的急性毒性。黑斑蛙胚胎和蝌蚪分别暴露系列浓度的BIT和 MIT,观察化学品对其生长、发育和运动的影响,计算96小时半数致死浓度（96 h-LC₅₀）和96小时半数致畸浓度（96 h-TC₅₀）,确定最小生长抑制浓度（MCIG）。结果发现,BIT对黑斑蛙胚胎的96 h-LC₅₀和96 h-TC₅₀分别为2.99 mg?L^-1和0.60 mg?L^-1,MCIG小于0.40 mg?L^-1,对蝌蚪的96 h-LC₅₀为6.44 mg?L^-1。MIT对黑斑蛙胚胎的96 h-LC₅₀和96 h-TC₅₀分别为5.30 mg?L^-1和2.36 mg?L^-1,MCIG为2.59 mg?L^-1,对蝌蚪的96 h-LC₅₀为7.58 mg?L^-1。根据《化学农药环境安全评价准则报批稿》中两栖动物蝌蚪急性毒性的分级标准,判定BIT和MIT的毒性等级为中等。该毒性数据为异噻唑啉酮类杀菌剂的环境管理提供参考。     

锌离子慢性暴露对中华大蟾蜍蝌蚪生长发育的影响

为评价水域环境中Zn~(2+)对两栖动物的毒性影响,本研究以中华大蟾蜍(Bufo gargarizans)蝌蚪为试验材料,对G26期蝌蚪进行了0、10、50、100和500μg·L~(-1)Zn~(2+)的慢性水体暴露直至蝌蚪发育至变态高峰期(G42期)。分别于暴露15 d和30 d后取样测定蝌蚪全长、体长、体重和发育分期各指标;此外,分析了Zn~(2+)慢性水体暴露对变态率、变态高峰期(G42)蝌蚪的全长、体长、体重、后肢长和骨骼发育的影响。结果表明:暴露15 d时,各浓度Zn~(2+)对中华大蟾蜍蝌蚪的生长发育均未造成显著影响,而持续暴露30 d后,500μg·L~(-1)Zn~(2+)处理组蝌蚪的生长发育受到显著抑制;各浓度Zn~(2+)慢性暴露均导致中华大蟾蜍蝌蚪变态率的下降,其中500μg·L~(-1)Zn~(2+)处理组的变态率最低;500μg·L~(-1)Zn~(2+)慢性暴露导致G42期中华大蟾蜍蝌蚪的形态指标(全长、体长、后肢长)和骨化程度均受到显著抑制。研究表明,水环境中高浓度锌对中华大蟾蜍幼体的生长发育和变态具有潜在的危害,水域锌污染所引发的毒理效应予以重视。     

环境中的PAES对蟾蜍蝌蚪红细胞微核的影响研究

通过对邻苯二甲酸酯对蟾蜍蝌蚪红细胞微核的影响进行了研究。目的探讨邻苯二甲酸酯对蟾蜍蝌蚪的致突变作用。方法以邻苯二甲酸二甲酯为污染物对蟾蜍蝌蚪染毒24小时,并观察其细胞核变化。所用蟾蜍蝌蚪处于变态期,对污染物较为敏感。结果邻苯二甲酸酯使蟾蜍蝌蚪红细胞微核率以及核异常细胞率上升,微核率随着浓度的增大而上升,在浓度为78 ug/ml,对照组相比有极显著差异P〈0.01,浓度在18.5 ug/ml时试验组突变的细胞核的形态发生显著改变,核异常细胞率与对照组核异常细胞率有显著差异P〈0.05。此时显微镜下观察可见微核、双核、核内凹、核碎裂、无丝分裂时核分裂不均等核的形态变化。结论邻苯二甲酸酯对蟾蜍蝌蚪具有明显的致突变作用。     

异噻唑啉酮类杀菌剂对黑斑蛙胚胎和蝌蚪的急性毒性

异噻唑啉酮类杀菌剂1,2-苯并异噻唑-3-酮(BIT)和甲基异噻唑啉酮(MIT)虽已在多种行业中广泛使用,但目前有关其毒性尤其对水体中生物毒性的数据还较少。鉴于BIT和MIT在水体中普遍存在,本文研究了这两种污染物对两栖动物黑斑蛙胚胎和蝌蚪的急性毒性。黑斑蛙胚胎和蝌蚪分别暴露系列浓度的BIT和MIT,观察化学品对其生长、发育和运动的影响,计算96小时半数致死浓度(96 h-LC50)和96小时半数致畸浓度(96 h-TC50),确定最小生长抑制浓度(MCIG)。结果发现,BIT对黑斑蛙胚胎的96 h-LC50和96 h-TC50分别为2.99 mg·L-1和0.60 mg·L-1,MCIG小于0.40 mg·L-1,对蝌蚪的96 h-LC50为6.44 mg·L-1。MIT对黑斑蛙胚胎的96 h-LC50和96 h-TC50分别为5.30 mg·L-1和2.36 mg·L-1,MCIG为2.59 mg·L-1,对蝌蚪的96 h-LC50为7.58 mg·L-1。根据《化学农药环境安全评价准则报批稿》中两栖动物蝌蚪急性毒性的分级标准,判定BIT和MIT的毒性等级为中等。该毒性数据可为异噻唑啉酮类杀菌剂的环境管理提供参考。     

Heavy metals and pesticides in anuran spawn and tadpoles,water, and sediment

High concentrations of metals (cadmium, copper, lead, and zinc) and of lindane were measured in the sediment and in the spawn and tadpoles of Bufo bufo, Rana dalmatina, and Rana ridibunda from two Austrian locations. Residues in spawn suggest maternal transfer. Increase of the metal concentrations from spawn to advanced tadpole stage is explained by the larval microphaguous feeding habits which cause high exposition of the tadpoles to substances concentrating in sediments and suspended particles. Metal and pesticide concentrations in spawn and tadpoles are toxic to various other aquatic organisms and are furthermore considered to be potentially hazardous to the anurans themselves. The results are conform with world‐wide observations of contamination of anuran larvae with heavy metals, and prove the significance of non‐point source chemical exposure due to allochthonous toxicant input by wind load and precipitation.     

Induction of micronuclei in tadpoles of Odontophrynus americanus (Amphibia: Leptodactylidae) by the pyrethroid insecticide cypermethrin

Cypermethrin (CY) is an active cyano pyrethroid effective against a wide range of pests encountered in agriculture and forestry. Although CY is not mutagenic in in vitro assays for gene mutation, in vivo assays showed conflicting results. In vivo genotoxicity of the synthetic pyrethroid CY in erythrocytes of Odontophrynus americanus tadpoles was examined. The frequency of micronuclei (MN) was recorded in blood smears obtained from tadpoles exposed in vivo to four different nominal concentrations 5, 10, 20 or 40?µg?L^?1 of the compound and fixed at two sampling times 48 and 96?h. As a positive control larvae were exposed to 40?mg?L^?1 of cyclophosphamide (CP). Tadpoles exposed to all CY treatments showed a significant increase in single small MN compared to the negative control group after 48?h and at 5 and 10?µg?L^?1 of CY at 96?h. Results obtained here demonstrated the genotoxic effects of the commercial formulation CY in the anuran larvae analyzed. Thus, data suggest that measurements of MN and other erythrocytes morphological aberrations performed in circulating blood samples of O. americanus tadpoles is a method for detecting cytogenetic damage in other native species.     

Mechanism of predator–prey detection and behavioral responses in some anuran tadpoles

Predator–prey relationship was studied in three sympatric species of anuran tadpoles. The study design consisted of allowing predaceous Hoplobatrachus tigerinus tadpoles to devour prey tadpoles (Sphaerotheca breviceps and Bufo melanostictus) placed in a plastic tub (five tadpoles of each species, stage ~27) in 30 min. In trials without refugia, more tadpoles of Bufo fell prey compared to Sphaerotheca. In contrast, provision of refugia using hydrilla plant reversed predation risk of the two species. The swimming speed (V _max = 64.55 ± 1.45 cm/s) of Hoplobatrachus tadpoles was much higher compared to the prey species (Bufo: 3.6 ± 0.4 cm/s; Sphaerotheca: 27.6 ± 1.6 cm/s). Poor swimming ability may account for the observed vulnerability of the Bufo tadpoles to predation especially in clear waters; refugia overcame predation to some extent. On the other hand, Sphaerotheca tadpoles that swim faster than the toad tadpoles were less vulnerable in open areas; refugia actually hindered swimming and increased predation. Experiments with association choice tests show that predaceous tadpoles detect prey based on both visual and chemical cues. On the other hand, the prey tadpoles detected predator based exclusively on chemical rather than visual cues. The antipredator defense strategy of the toad tadpoles is manifested in the form of reduced movements, remaining still for longer times and, increased burst speed. The present findings also suggest that in both prey species predator detection has a genetic basis since naive tadpoles with no prior exposure to predators exhibit fright response on first encounter with them.