Tolerance of benzalkonium chloride, formalin, malachite green, and potassium permanganate in goldfish and zebrafish

OBJECTIVE: To determine tolerance of goldfish and zebrafish to benzalkonium chloride, formalin, malachite green, and potassium permanganate. DESIGN: Tolerance study. ANIMALS: Adult goldfish (Carassius auratus) and zebrafish (Danio rerio). PROCEDURES: Groups of fish (n = 10/group) were exposed to each disinfectant at the therapeutic dosage; at 0.25, 0.5, 3, and 5 times the concentration used for the therapeutic dosage; and at the concentration used for the therapeutic dosage but for 3 or 5 times the recommended exposure time. RESULTS: In both species, exposure to malachite green at the therapeutic dosage resulted in toxic effects, including death. Exposure to formalin at the therapeutic dosage resulted in toxic effects in goldfish, but not zebrafish, and exposure to potassium permanganate resulted in toxic effects in zebrafish, but not goldfish. On the basis of the ratio of therapeutic dosage to median lethal dosage, in goldfish, formalin was more toxic than benzalkonium chloride, which was more toxic than malachite green, which was more toxic than potassium permanganate. In zebrafish, potassium permanganate was more toxic than formalin and benzalkonium chloride, which were approximately equally toxic and more toxic than malachite green. Extending treatment time increased the toxicity of potassium permanganate in zebrafish and the toxicity of formalin and malachite green in goldfish, but did not alter the toxicity of the other disinfectants. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that there was no consistency between zebrafish and goldfish in their tolerance to disinfectants, and that therapeutic dosages reported in the literature for these disinfectants were not always safe.     

Evaluation of zebrafish Danio rerio as a model for enteric septicemia of catfish (ESC)

Zebrafish (also known as zebra danio) Danio rerio were injected intramuscularly with Edwardsiella ictaluri at doses of 6 x 10(3), 6 x 10(4), or 6 x 10(5) colony-forming units per gram (CFU/g) or sterile phosphate-buffered saline (sham) or were not injected. Mortality occurred from 2 to 5 d postinjection (dpi) at rates of 0, 76.6, and 81.3% for the low, medium, and high doses, respectively, and E. ictaluri was isolated from dead fish. Survivors were sampled at 10 dpi and E. ictaluri was not isolated. Sham-injected and noninjected controls did not suffer mortality. Histopathology trials were performed in which zebrafish were injected with 1 x 10(4) CFU/g or sham-injected and sampled at 12, 24, 48, 72, and 96 h postinjection for histological interpretation. Collectively, these zebrafish demonstrated increasing severity of splenic, hepatic, cardiac, and renal interstitial necrosis over time. To evaluate the progression of chronic infection, zebrafish were injected with 1 x 10(2) CFU/g and held for 1 month postinjection. Beginning at 12 dpi and continuing for an additional 2 weeks, zebrafish demonstrated abnormal spiraling and circling swimming behaviors. Histopathology demonstrated necrotizing encephalitis. In immersion trials, zebrafish were exposed to low, medium, and high doses (averaging 1.16 x 10(5), 1.16 x 10(6), and 1.16 x 10(7) CFU/mL of tank water) of E. ictaluri for 2 h. Mortality occurred from 5 to 9 d postexposure at rates of 0, 3.3, and 13.3% for the low, medium, and high doses, respectively; E. ictaluri was isolated from dead fish. Channel catfish Ictalurus punctatus exposed to the medium doses suffered 100% mortality, and E. ictaluri was isolated from these fish. This study demonstrates the potential use of zebrafish as a model for E. ictaluri pathogenesis.     

Retinal neuronal cell is a toxicological target of tributyltin in developing zebrafish

Organotins are among the most common marine pollutants in the world, as they are widely used as antifouling paint on ships and fishing nets. It has been reported that organotin preferentially accumulates in the central nervous system, especially in the retinal neurons of marine organisms including fish. In this study, we investigated the effects of waterborne tributyltin (TBT) on early-stage developing zebrafish (Danio rerio). Below the lethal concentrations, TBT specifically increased the number of apoptotic cells in the retina as well as some cells near trigeminal neurons, detected by terminal transferase-mediated nick-end-labeling staining. Apoptosis peaked at 60 hpf and decreased by 72 hpf, which was associated with macrophage accumulation. Furthermore, the effect of TBT was markedly inhibited by antioxidants, ascorbic acid or trolox. These results suggest that TBT preferentially induces apoptosis in the retinal neuron of developing zebrafish. Oxidative stress may be involved in this toxicological response.     

Protective effects of phlorotannins against ultraviolet B radiation in zebrafish (Danio rerio)

Exposure to ultraviolet B (UV-B) radiation has been associated with a variety of adverse effects in all forms of life, including micro-organisms, plants, animals and humans. Ultraviolet B induces cell damage at the molecular level and consequently organisms must employ strategies to protect themselves from sunlight and to repair UV-B-induced cellular damage. In this study, the UV-B protective effects of four different phlorotannins isolated from a brown alga (Ecklonia cava) were determined using zebrafish (Danio rerio) as an in vivo model. Zebrafish embryos were pretreated with phlorotannins and exposed to UV-B (50 mJ/cm(2)). The heart rate, generation of reactive oxygen species and nitric oxide, cell death and hyperpigmentation were assessed in order to evaluate UV-B-induced photo-damage. Treatment of the embryos with the algal phorotannins reduced UV-B-induced reactive oxygen species and nitric oxide levels, protected against UV-B-induced cell death and significantly reduced hyperpigmentation. We therefore suggest that phlorotannins isolated from E. cava can protect against UV-B radiation. Editor Note. Readers of the journal may be unfamiliar with the use of zebrafish embryos in research studies. There is no indication in this article of an ethical review of the study. This is because the use of fish embryos in research, at least in the UK, is not subject to a licensing procedure if they are less than 5 days post fertilization (dpf). In this study the embryos were 2 dpf.     

Effect of cytochrome P450 inhibition on toxicity of diclofenac in chickens: Unravelling toxicity in Gyps vultures

Diclofenac was responsible for the decimation of Gyps vulture species on the Indian subcontinent during the 1980s and 1990s. Gyps vultures are extremely sensitive (the lethal dose 50 [LD_50] ~ 0.1 mg/kg – 0.2 mg/kg), with toxicity appearing to be linked to metabolic deficiency, demonstrated by the long T_1/2 (~12 h – 17 h). This is in striking comparison to the domestic chicken (Gallus gallus domesticus), in which the LD₅₀ is ~10 mg/kg and the T_1/2 is ~1 h. The phase 1 cytochrome P450 (CYP) 2C subfamily has been cited as a possible reason for metabolic deficiency. The aim of this study was to determine if CYP2C9 homolog pharmacogenomic differences amongst avian species is driving diclofenac toxicity in Gyps vultures. We exposed each of 10 CYP-inhibited test group chickens to a unique dose of diclofenac (as per the Organisation for Economic Co-operation and Development [OECD] toxicity testing guidelines) and compared the toxicity and pharmacokinetic results to control group birds that received no CYP inhibitor. Although no differences were noted in the LD₅₀ values for each group (11.92 mg/kg in the CYP-inhibited test group and 11.58 mg/kg in the control group), the pharmacokinetic profile of the test group was suggestive of partial inhibition of CYP metabolism. Evaluation of the metabolite peaks produced also suggested partial metabolic inhibition in test group birds, as they produced lower amounts of metabolites for one of the three peaks demonstrated and had higher diclofenac exposure. This pilot study supports the hypothesis that CYP metabolism is varied amongst bird species and may explain the higher resilience to diclofenac in the chicken versus vultures.     

香泽兰总黄酮对斑马鱼脾脏毒性病理组织学作用

为了探索香泽兰总黄酮对斑马鱼脾脏显微组织结构的毒性作用,采集香泽兰全草,用70%乙醇(v/v)浸泡后,辅以超声提取,再经大孔树脂柱层析纯化,浓缩,冰冻干燥,制得香泽兰总黄酮冻干粉,用此总黄酮冻干粉按不同浓度对斑马鱼进行水触媒染毒,21 d后取脾脏,制作石蜡切片,苏木精-伊红染色,显微观察。结果发现,随着香泽兰总黄酮水触媒染毒浓度的增加,供试斑马鱼脾脏显微组织结构出现了不同程度的病变,主要表现含铁血黄素沉着增多,脾窦扩张,脾脏内淋巴细胞增多,血细胞核浓缩、溶解,甚至导致脾脏坏死。说明一定浓度的香泽兰总黄酮对斑马鱼脾脏具有一定的毒性作用。     

Lack of postexposure analgesic efficacy of low concentrations of eugenol in zebrafish

Objective

To test the postexposure analgesic efficacy of low doses of eugenol in zebrafish.

Application of peracetic acid for the treatment of juvenile sander (Sander lucioperca) during Ichthyophthirius multifiliis infestation

White spot disease caused by the ciliate protozoan parasite Ichthyophthirius multifiliis (I. m.), is one of the most dangerous diseases in aquaculture and ornamental fish breeding worldwide. The parasite is characterized by three developmental stages: a reproductive tomont, an infective theront and a parasitic trophont. In sander (Sander lucioperca) breeding I. m. causes serious economic losses. After banning of the traditional therapeutic agent malachite green we have to face a state of emergency for the treatment of the ichthyophthiriasis in Germany. The peracetic acid (PAA), characterized by positive therapeutical properties, might close this gap. The purpose of our investigations was the determination of the toxicity of PES to juvenile sander as well as the evaluation of the therapeutic effectiveness of the substance to combat I. m. For juvenile sander (length 3 cm) we determined a 24-h-LC50 of 1.14 (0.97; 1.3) ppm PES. In two investigations PAA was applied in daily intervals of 0.5; 1, 3, 5 and 24 h and concentrations of 0.5; 1; 1.5 and 2 ppm to treat I.-m.-infection in sander. In test I all sander (length 9 cm) died as a result of the I.-m.-infection. However, the PAA exposed fish survived longer than the PES-free controls! This might be due to a disinfection of other pathogens by PAA. In test II, the fish (length 12 cm) were less infected than fish in test I. Four of six fish died in the group exposed with 2 ppm PAA for 24 hours. The abundance of I.-m.-trophonts was determined in mucus, fin and gill tissues of all fish. Significant differences could not be observed between test I and test II because of dissimilar: 1. exposure in time and concentration, 2. age and condition of the fish and 3. homogenity of the variances. Therefore, no therapy strategy was successful while fighting the parasitic trophonts protected by the overlaying fish tissues. We speculate that a successful therapy of I. m. with PAA is, as known e.g. for malachite green, only possible while fighting the free living stages theronts and tomonts. This will be part of our subsequent investigations.     

Safety of Strontium Chloride as a Skeletal Marking Agent for Pacific Salmon

Abstract

The purpose of this study was to evaluate the biological effects associated with administering strontium chloride as a marking agent to age-0 Chinook Salmon Oncorhynchus tshawytscha fry. Fish were held in a 0× (0 mg/L), 1× (3,000 mg/L; current standard dosage), 3× (9,000 mg/L), or 5× (15,000 mg/L) solution of strontium chloride for 72 h (three times the standard duration of 24 h). The mortality among fish in the 5× strontium chloride exposure group was significantly higher than that observed in the other groups. A dose-related effect on general fish behavior and on feeding behavior was observed. Fish in all test tanks appeared to feed to satiation, except for fish in the 5× tanks during days 2 and 3. Fish in all other test tanks behaved normally. No dose-related effect on fish growth was detected. Histopathological evaluations showed that fish in the 5× exposure group had a significantly higher number of gill lesions than the 0× group. Our mortality, behavioral, and histological assessments suggested that juvenile Chinook Salmon could be safely immersed for three consecutive days in a 9,000-mg/L solution of strontium chloride. This finding potentially expands the present 1,000–3,000-mg/L dosage and 24-h holding period that can be used to mark juvenile fish with strontium chloride solutions. The research also provides necessary target animal safety data for U.S. Food and Drug Administration approval of strontium chloride as an alternative marking method that is suitable for fish with a short holding time.

Received February 19, 2017; accepted July 16, 2017 Published online September 22, 2017     

Tests to determine LC50 and discriminating doses for macrocyclic lactones against the cattle tick, Boophilus microplus

Laboratory tests were carried out on larvae and adults of the cattle tick Boophilus microplus to determine the toxicity of macrocyclic lactone acaricides (MLs). Technical and commercial MLs were used in larval packet test (LPT), larval immersion test (LIT) and adult immersion test (AIT). In LIT and AIT the toxicity of MLs was much higher than for LPT. In the AIT, diluting the injectable formulation of MLs in water was as effective as dilution in ethanol+Triton X-100. LC50, LC99.9 and 95% confidence limits were determined so that a discriminating dose (DD) could be set for larval and adult tests in order to diagnose potential resistance to MLs in field samples of the tick. These DDs are for Australian strains of B. microplus and may not be suitable for other strains until further work is carried out.The value of these diagnostic tests can only be verified if or when resistance to MLs emerges in ticks.     

铅、铬和硒对玫瑰无须鱼巴毒性的初步研究

采用玫瑰无须鱼巴的水生毒性试验法对Pb2 + 、Cr6+ 、Se6+ 3种金属离子的生物毒性进行了初步研究。结果表明 ,3种金属离子对玫瑰无须鱼巴均有较高的毒性 ,有明显的时效性、剂量依赖性和毒性差异 ,且有不同的作用特点。Pb2 + 离子对玫瑰无须鱼巴的毒性最低 ,其最高存活质量浓度为 10 0mg/L ,最低全部死亡质量浓度为 2 0 0mg/L ;Cr6+ 离子的毒性次之 ,最高存活质量浓度为 2 0mg/L ,最低全部死亡质量浓度为 2 0 0mg/L ;Se6+ 离子的毒性最高 ,最高存活质量浓度为 2 0mg/L ,最低全部死亡质量浓度为 12 0mg/L。随着 3种金属离子质量浓度的升高 ,玫瑰无须鱼巴的死亡率逐渐升高 ,就同一离子浓度而言 ,随着作用时间的延长 ,玫瑰无须鱼巴的死亡率逐渐升高 ,均无性别差异。用直线内切法分别得到 3种金属离子不同时间对玫瑰无须鱼巴的半数致死质量浓度 (LC50 )。     

Comparison of two formulations of alfaxalone for immersion anaesthesia in laboratory zebrafish (Danio rerio)

ObjectiveTo compare two commercial formulations of alfaxalone for immersion anaesthesia in laboratory zebrafish.Study designProspective, blinded, randomized study.AnimalsA total of 20 adult Danio rerio (Tuebingen strain).MethodsZebrafish were divided into two groups of 10 (five female, five male) and placed in individual immersion baths containing 10 mg L^–1 of unpreserved alfaxalone (group 1) or preserved alfaxalone (group 2). Anaesthetists blinded to treatment used a composite score scale (CSS) (range 0–12) to assess fish every 30 seconds until induction of anaesthesia. Anaesthetic induction occurred when equilibrium and response to stimulus were lost. Fish were then placed in a clean water bath and scored every 60 seconds. Recovery from anaesthesia was defined as a CSS of ≤ 1. Time variables recorded were anaesthetic induction time (AIT), anaesthetic recovery time (ART) and total procedure time (TPT). Fish were observed for evidence of roupgross external pathology during the procedure. Following anaesthesia, four fish from each group were randomly chosen and euthanized for gill histopathology analysis immediately after recovery criteria were met. Data are presented as mean ± standard deviation. An independent t test was used to compare the difference in average anaesthetic time variables between groups (α = 0.05).ResultsThere were no statistical differences between groups in reported variables. TPT, AIT and ART were 10.2 ± 1.2, 1.9 ± 0.9 and 8.3 ± 1.2 minutes for group 1 and 10.8 ± 2.9, 2.4 ± 1.2 and 8.4 ± 2.7 minutes for group 2. No gross external pathology was evident, and no fish died during the experimental period. Histopathology showed normal gill pathology and no difference between the groups.Conclusions and clinical relevanceImmersion anaesthesia using 10 mg L^–1 of either formulation of alfaxalone resulted in anaesthesia of similar quality and duration.     

重金属污染物对卤虫无节幼体的毒性

在水温为(27±0.5)℃,盐度为7°B′e和连续充气条件下,采用动态活水法研究了汞、铅、铜、锰、铬对卤虫无节幼体的毒性效应及联合毒性作用。结果表明,5种金属对卤虫无节幼体的48hLC50分别是0.023、1.31、2.10、12.15、28.91mg/l。毒性由强至弱依次为Hg2+>Pb2+>Cu2+>Mn2+>Cd2+,Hg-Cu、Cu-Mn对卤虫幼体的联合作用表现为拮抗作用,Pb-Cu、Pb-Mn、Mn-Cd则表现为协同作用。     

Molluscicidal activity of Carica papaya and Areca catechu against the freshwater snail Lymnaea acuminata

The molluscicidal activity of seed and lyophilized latex powder of Carica papaya and seed powder of Areca catechu against the vector snail Lymnaea acuminata was studied. The toxicity of these plant products was time and dose dependent. The toxicity of C. papaya lyophilized latex powder (LC(50) at 96 h: 8.38 mg/l) was more pronounced than that of A. catechu seed powder (LC(50) at 96 h: 12.32 mg/l) and C. papaya seed powder (LC(50) at 96 h: 61.56 mg/l). Ethanolic extracts of C. papaya seed and A. catechu seed were more toxic than their other extracts. The ethanolic extract of A. catechu seed (LC(50) at 24h: 17.21 mg/l) was more effective than the ethanolic extract of C. papaya seed (LC(50) at 24h: 53.38 mg/l). The LC(50) of column-purified fraction of A. catechu seed at 96 h was 3.99 mg/l, whereas that of C. papaya seed was 7.06 mg/l. C. papaya and A. catechu may be used as potent molluscicides since the concentrations used to kill the snails were not toxic for the fish Colisa fasciatus which shares the same habitat with the snail L. acuminata.     

A preliminary study of dietary protein requirement of juvenile marbled flounder (Pseudopleuronectes yokohamae)

An 8-week feeding trial was conducted to determine the optimal dietary protein level for juvenile marbled flounder. Five semi-purified test diets were formulated to contain different protein levels (CP) including 42.7%, 47.4%, 53.3%, 58.8%, and 64.5% (dry matter), named as CP42.7, CP47.4, CP53.3, CP58.8, and CP64.5, respectively. Five hundred and twenty-five juveniles (6.0 ± 0.1 g) were randomly distributed into 15 tanks (300 L tanks), resulting in 35 fish per tank (n = 3 tanks). Fish were fed the test diets 5 times per day until satiation. The CP58.8 resulted in the highest gain in weight and the best efficiency in feed utilization among the tested protein levels (P < 0.05). Fish fed the CP58.8 diet showed significantly higher whole-body protein and lipid contents than the fish that were fed the other diets (P < 0.05). Fish fed the CP53.3, CP58.8, and CP64.5 diets showed a significantly higher dorsal-muscle lipid content than the fish that were fed the CP42.7 and CP47.4 diets (P < 0.05). The one-slope straight broken-line regression analysis on the results of the thermal growth coefficient and feed conversion ratio indicated that the estimated optimum dietary protein level was 58.8%. Taken together, it is suggested that the dietary protein level of 58.8% is optimal for better growth and high efficiency in feed utilization for the juvenile marbled flounder.     

Evaluation of Zebrafish Danio rerio as a Model for Enteric Septicemia of Catfish (ESC)

Abstract

Zebrafish (also known as zebra danio) Danio rerio were injected intramuscularly with Edwardsiella ictaluri at doses of 6 × 10³, 6 × 10⁴, or 6 × 10⁵ colony-forming units per gram (CFU/g) or sterile phosphate-buffered saline (sham) or were not injected. Mortality occurred from 2 to 5 d postinjection (dpi) at rates of 0, 76.6, and 81.3% for the low, medium, and high doses, respectively, and E. ictaluri was isolated from dead fish. Survivors were sampled at 10 dpi and E. ictaluri was not isolated. Sham-injected and noninjected controls did not suffer mortality. Histopathology trials were performed in which zebrafish were injected with 1 × 10⁴ CFU/g or sham-injected and sampled at 12, 24, 48, 72, and 96 h postinjection for histological interpretation. Collectively, these zebrafish demonstrated increasing severity of splenic, hepatic, cardiac, and renal interstitial necrosis over time. To evaluate the progression of chronic infection, zebrafish were injected with 1 × 10² CFU/g and held for 1 month postinjection. Beginning at 12 dpi and continuing for an additional 2 weeks, zebrafish demonstrated abnormal spiraling and circling swimming behaviors. Histopathology demonstrated necrotizing encephalitis. In immersion trials, zebrafish were exposed to low, medium, and high doses (averaging 1.16 × 10⁵, 1.16 × 10⁶, and 1.16 × 10⁷ CFU/mL of tank water) of E. ictaluri for 2 h. Mortality occurred from 5 to 9 d postexposure at rates of 0, 3.3, and 13.3% for the low, medium, and high doses, respectively; E. ictaluri was isolated from dead fish. Channel catfish Ictalurus punctatus exposed to the medium doses suffered 100% mortality, and E. ictaluri was isolated from these fish. This study demonstrates the potential use of zebrafish as a model for E. ictaluri pathogenesis.     

Phenotypic plasticity induced using high ambient temperature during embryogenesis in domesticated zebrafish,Danio rerio

Ambient temperature during early stages of life has a substantial effect on physiological processes, eliciting phenotypic plasticity during zebrafish developmental stages. Zebrafish are known to possess a noteworthy ability to modify their phenotype in dependence of environmental factors. However, there is a poor understanding of the effects of temperature during embryogenesis, which influences the biological functions such as survival ability and masculinization in later developmental stages. Since the middle embryonic phase (pharyngula period) is genetically the most conserved stage in embryogenesis, it is very susceptible to embryonic lethality in developmental processes of vertebrates. Here, we tested the effect of transient perturbations (heat shock) during early development (5–24 hr post‐fertilization; hpf) at 35°C compared to control group at 28°C, on survival ability of zebrafish to study the embryonic and post‐embryonic mortality. We studied the variation of heat‐induced masculinization among and across the families in response to high temperature. Furthermore, morphometric traits of adult zebrafish at different developmental time points were measured in order to estimate the temperature × sex interaction effect. We found the highest embryonic mortality around the gastrula and segmentation periods in both experimental groups, with significantly lower survival ability in the temperature‐treated group (73.30% ± 0.58% vs. 70.19% ± 0.57%, respectively). A higher hatching success was observed in the control group (71.08% ± 0.61%) compared to the heat‐induced group (67.95% ± 0.60%). A distinct reduction in survival ability was also observed in both experimental groups during the first two weeks after hatching, followed by a reduced level of changes thereafter. We found sex ratio imbalances across all families, with 25.2% more males under temperature treatment. Our study on growth performance has shown a positive effect of increased temperature on growth plasticity, with a greater impact on female fish in response to high ambient temperature.     

In vivo alternative testing with zebrafish in ecotoxicology

Although rodents have previously been used in ecotoxicological studies, they are expensive, time-consuming, and are limited by strict legal restrictions. The present study used a zebrafish (Danio rerio) model and generated data that was useful for extrapolating toxicant effects in this system to that of humans. Here we treated embryos of the naive-type as well as a transiently transfected zebrafish liver cell line carrying a plasmid (phAhRE-EGFP), for comparing toxicity levels with the well-known aryl hydrocarbon receptor (AhR)-binding toxicants: 3,3'',4,4'',5-pentachlorobiphenyl (PCB126), 2,3,7,8-tetrachlorodibenzo-p-dioxin, and 3-methylcholanthrene. These toxicants induced a concentration-dependent increase in morphological disruption, indicating toxicity at early life-stages. The transient transgenic zebrafish liver cell line was sensitive enough to these toxicants to express the CYP1A1 regulated enhanced green fluorescent protein. The findings of this study demonstrated that the zebrafish in vivo model might allow for extremely rapid and reproducible toxicological profiling of early life-stage embryo development. We have also shown that the transient transgenic zebrafish liver cell line can be used for research on AhR mechanism studies.     

三种药物对西施舌稚贝的急性毒性研究

在常温静水条件下,进行敌百虫、甲醛和鳗菌净对西施舌稚贝的急性毒性试验。结果表明:敌百虫、甲醛和鳗菌净对西施舌稚贝的24hLC50分别为26.75mg/L、54.25mg/L、1.47mg/L,其安全浓度分别为0.27mg/L、0.54mg/L、0.01mg/L。本文探讨如何有效地使用药物杀灭西施舌稚贝的敌害生物,以保证西施舌人工育苗成功。     

植物源农药苦参碱对部分桑园害虫的毒力及田间防治效果

为了探讨从传统中草药苦参中提取的苦参碱用于桑树害虫防治的可行性,用2%苦参碱稀释药液对部分桑园害虫进行室内毒力测定和田间防治试验,并检测其对家蚕的安全性。结果表明,2%苦参碱对桑尺蠖、桑毛虫、棉大造桥虫、红腹灯蛾、白毛虫有较强的毒力,其LC50分别为23.55、28.73、28.52、30.71、25.61 mg/L,以1 500倍稀释药液对上述5种害虫室内处理24 h后的死亡率为92.18%～96.78%,并且具有较好的田间防治效果,24 h虫口退减率为89.81%～96.00%;对桑园微型害虫桑蓟马和朱砂叶螨也有较强的毒力和防治效果,1 500倍稀释药液室内处理24 h后的死亡率分别为95.52%、98.07%,田间防治24 h虫口退减率分别为90.61%、92.55%;对桑螟、野桑蚕的毒力较低,LC50分别为364.47和351.01 mg/L,1 500倍稀释药液对2种害虫室内处理24 h后的死亡率仅有3.13%和3.83%,田间防治24 h虫口减退率分别为18.06%、8.70%。用2%苦参碱的2 000倍、1 500倍、1 000倍稀释药液喷施桑树后,对家蚕的安全间隔期分别为4、8、32 h,安全间隔期后采摘桑叶喂蚕,对家蚕的生长发育和产茧量性状无不良影响。根据试验结果初步认为:苦参碱对桑园害虫防治具有选择性药效,如果桑园害虫的优势种群为桑尺蠖、棉大造桥虫、桑毛虫、红腹灯蛾、白毛虫、桑蓟马、朱砂叶螨,可以考虑采用苦参碱进行防治。