Acute effects of methyl parathion and diazinon as inducers for oxidative stress on certain biomarkers in various tissues of rainbowtrout (Oncorhynchus mykiss)

Present study aimed mainly to assess oxidative stress pesticides such as methyl parathion (MP) and diazinon, which are widely used insecticides and contaminate aquatic ecosystems, on certain biomarkers in various tissues of rainbowtrout (Oncorhynchcus mykiss). Biomarkers selected for stress monitoring were malondialdehyde (MDA) and antioxidant defense system (ADS) mainly reduced glutathione (GSH), glutathione reductase (GR), peroxidase (GSH-PX), transferase (GST) and superoxidedismutase (SOD) activities in the liver, gills and muscle of fishes exposed to 0.5 and 1 ppm dosages of MP and diazinon for 24, 48 and 72 h. According to these results, after the administrations of MP and diazinon promote MDA content in some of the tissues of fishes treated with both dosages of MP and diazinon. With regard to the ADS, GSH-Px, GST, SOD, GR activities and GSH levels fluctuated after 24, 48 and 72 h in all the treatment groups compared with controls. Collective results demonstrated that exposure of fish to pesticides induced an increase in MDA joined with fluctuated ADS. This may reflect the potential role of these parameters as useful biomarkers for assessment of water pollution.     

Acute toxicity and histopathological effects of sublethal fenitrothion on Nile tilapia, Oreochromis niloticus

Organophosphothionate insecticide fenitrothion is known as potential toxic pollutant contaminating aquatic ecosystems. The effects of fenitrothion were studied to determine the 96 h LC₅₀ value on Nile tilapia (Oreochromis niloticus) and investigate histopathological responses of fish exposed to sublethal fenitrothion concentrations. Data obtained from the fenitrothion acute toxicity tests were evaluated using the Probit Analysis Statistical Method. The 96 h LC₅₀ value and 95% confidence limit for Nile tilapia (58.70 ± 6.97 g) was estimated as 0.84 (0.68-1.15) mg/L. Behavioral changes were observed closely during the acute toxicity test. The bioassay experiments were repeated three times and static test method was used. Some fish exposed to 96 h 0.1, 0.5 mg/L fenitrothion concentrations showed histopathological alterations in the gills, liver, kidney, brain and testes. Severely deformations were observed at 0.5 mg/L fenitrothion on the gills lamella such as hyperemia, epithelial hyperplasia, fusion and telangiectasis, in the liver tissue such as cloudy swelling, hydropic degenerations and lipid infiltration. In addition hyperemia and hemorrhage observed in kidney tissue and hyperemia was determined in brain tissue.     

Effects of the organophosphate pesticide Folidol 600® on the freshwater fish, Nile Tilapia (Oreochromis niloticus)

Nile Tilapia (Oreochromis niloticus) juveniles were exposed to different concentrations of Folidol 600® in static toxicity tests. The 24, 48, 72 and 96 h LC₅₀ values of Folidol 600® to O. niloticus were 17.82, 8.91, 4.00 and 2.70 mg L⁻¹, respectively. The values of hematological parameters increased, and inhibition of cholinesterases activity (AChE, BChE and PChE) in plasma of fish exposed to the higher concentrations of pesticide reached 94%. Furthermore, the exposure of Tilapia to Folidol 600® caused an increase of 4%, 20% and 38.4% in oxygen consumption at 0.1, 0.5 and 1.0 mg L⁻¹, respectively. However, exposure to 2.5, 5.0 and 10 mg L⁻¹ caused a decrease of 33.6%, 35.2% and 42.4% in oxygen consumption relative to the control. The ammonium excretion of fish exposed to 0.0, 0.1, 0.5, 1.0, 2.5, 5.0 and 10.0 mg Folidol 600®/L was 0.12, 0.18, 0.30, 0.33, 0.37, 0.36 and 0.33 μg/g/min, i.e., 50%, 150%, 175%, 208%, 200% and 175% increase, respectively, relative to the control.     

N'-硝基缩氨基胍类化合物对蚜虫的室内毒力测定及相关酶活性的影响

Su50[N'-硝基-1-异丙基-2-(4-硝基苯亚甲基)氨基胍]和Su56(N'-硝基-1-烯丙基-2-正丙基氨基胍)是利用活性亚结构拼接原理合成的具有新烟碱类和缩氨基脲类杀虫剂共同结构特征的硝基缩氨基胍类化合物。为了解Su50和Su56对蚜虫的生物活性及作用机理,采用叶片浸渍法测定了其对多种蚜虫的杀虫活性,用棉叶涂抹药液后接入棉蚜Aphis gossypii Glover测定了其对棉蚜的拒食活性,并采用生化方法测定了不同亚致死浓度(LC_(10)、LC_(25))Su56对棉蚜羧酸酯酶(CarE)、乙酰胆碱酯酶(AChE)、谷胱甘肽S-转移酶(GSTs)和多功能氧化酶(MFO)的酶活性的影响。结果表明:Su50和Su56对棉蚜A.gossypii/桃蚜Myzus persicae Sulzer,苹果黄蚜Aphis citricola van der Goot和梅大尾蚜Hyalopterus amygdali Blanchard均具有一定的杀虫活性,但毒力差异不显著,其中Su50对棉蚜、桃蚜、梅大尾蚜和苹果黄蚜的LC_(50)值分别为13.0、24.2、62.6和14.3mg/L,Su56的LC_(50)值则分别为30.3、30.2、101和3.23 mg/L;同时Su50和Su56对供试棉蚜均具有一定的拒食活性。生化试验结果表明,Su56在LC_(10)和LC_(25)浓度下对棉蚜的CarE、GSTs和MFO酶活性无显著影响,但在LC_(10)浓度下对棉蚜的ACNE酶活性却有显著抑制作用。     

Effect of short term exposure of fenvalerate on biochemical and haematological responses in Labeo rohita (Hamilton) fingerlings

Experiment was carried out to determine the median lethal concentration (LC₅₀) of fenvalerate to Labeo rohita fingerlings. After determining the LC₅₀ value of fenvalerate, a sub-lethal concentration (1/3rd of LC₅₀) of fenvalerate was exposed for 15 days. Significant alterations in SOD (P < 0.05) activity of liver and gill was observed due to fenvalerate. Catalase activity in gills of fishes was also affected significantly (P < 0.05). WBC, NBT and Hct values were reduced significantly in fenvalerate exposed fishes as compared to control group, whereas blood glucose level showed higher values in fenvalerate exposed group. Serum total protein and albumin were also reduced significantly as a result of fenvalerate exposure. Significant increase in the serum GOT, serum GPT, creatinine, triglyceride and serum ACP was noticed after 15 days of fenvalerate exposure. Results indicated that short term exposure of fenvalerate can induce biochemical and haematological alterations causing stress to L. rohita fingerlings.     

Endocrine disruption and metabolic changes following exposure of Cyprinus carpio to diethyl phthalate

Diethyl phthalate (DEP) enter into aquatic environment from industries manufacturing cosmetics, plastic and many commercial products and can pose potential fish and human health hazard. This experiment evaluated effects of DEP in adult male (89 g) common carp (Cyprinus carpio) by exposing them to fractions of LC₅₀ (1/500-1/2.5) doses with every change of water for 28 days. Vitellogenin induction metabolic enzymes, somatic indices and bioaccumulation were studied on 7th, 14th, 21st and 28th day. The 96th hour LC₅₀ of DEP in fingerlings was found to be 48 mg/L. Compared to control, except increase (P < 0.01) in alkaline phosphatase activity (EC 3.1.3.1) and liver size, there was decrease (P < 0.01) in activity of acid phosphatase (EC 3.1.3.2), aspartate aminotransferase (EC 2.6.1.1), alanine aminotransferase (EC 2.6.1.2) and testiculosomatic index following exposure to 1, 5 and 20 ppm DEP. Significant (P < 0.01) dose dependant vitellogenin induction was observed with exposure of fish to 0.1, 1 and 5 ppm DEP. The bioaccumulation of DEP in testis, liver, brain, gills and more importantly in muscle tissues of fish increased significantly (P < 0.01) with increase of dose from 1 to 5 ppm. Significant interaction (P < 0.01) of dose and duration of exposure indicated that exposure period of a week to two was sufficient to bring about changes in quantifiable parameters studied. Fish exposed to 20 ppm DEP became lethargic and discolored during onset of the 4th week. This is the first report describing metabolic changes and vitellogenin induction following exposure of C. carpio to DEP dose that is as low as 1/500th fraction of LC₅₀.     

Toxicity and metabolism of endosulfan and its effect on oxygen consumption and total nitrogen excretion of the fish Macrognathus aculeatum

Experiments were conducted with the freshwater fish Macrognathus aculeatum to study the toxicity and metabolism of endosulfan and the effect of the pesticide on the oxygen consumption and total nitrogen excretion. The 96-hr LC₅₀ value was 3.5 ± 0.2 ppb. In brain, gills, gut, liver, and kidney, endosulfan was metabolized to endosulfan sulfate, but this appears to be only an intermediary step as the nontoxic endosulfan ether was found only in the liver and kidney, the principal organs of elimination of toxicants in fish. The pesticide, both at sublethal and lethal concentrations, decreased oxygen consumption and total nitrogen excretion.     

亚致死浓度毒死蜱对小麦禾谷缢管蚜生长和繁殖的影响

为探讨毒死蜱对小麦禾谷缢管蚜Rhopalosiphum padi(Linnaeus)的亚致死效应,采用玻璃管药膜法确定了其亚致死浓度(LC10、LC20和LC30),并研究了该浓度下毒死蜱对小麦禾谷缢管蚜生长和繁殖的影响。结果表明:以LC10、LC20和LC30浓度处理后,禾谷缢管蚜成蚜的寿命分别为(8.60±0.22)、(8.03±0.18)和(6.68±0.18)d,均显著短于对照的(10.36±0.31)d;单雌产仔量分别为(21.88±0.63)、(20.41±0.53)和(16.68±0.35)只,也均显著少于对照的(26.40±0.89)只;产仔历期分别为(7.55±0.22)、(6.69±0.17)和(5.64±0.15)d,均显著短于对照的(9.13±0.31)d;试验浓度药剂处理对下一代若蚜期的影响不显著;LC30浓度处理对下一代成蚜繁殖有显著的抑制作用,可减少单雌产仔量3.74只,缩短产仔历期1.39 d。生命表参数分析表明:LC30浓度毒死蜱处理使小麦禾谷缢管蚜的净增殖率(R0)比对照降低了34.71%,使种群加倍时间(t)比对照延长了17.37%;LC20浓度处理使小麦禾谷缢管蚜的平均世代历期(T)延长了12.59%;LC10浓度处理组各项指标与对照间无显著性差异。研究表明,亚致死浓度毒死蜱能够缩短小麦禾谷缢管蚜成蚜的寿命,降低其繁殖力,该结果对小麦禾谷缢管蚜综合防治策略的制定具有积极意义。     

Deltamethrin induced alterations of hematological and biochemical parameters in fingerlings of Catla catla (Ham.) and their amelioration by dietary supplement of vitamin C

The present study was carried out to investigate the sub-lethal toxicity of technical grade deltamethrin (a synthetic pyrethroid) of concentration 1.61 μg/L (1/3rd of 96 h LC₅₀) on hematological and biochemical parameters of catla (Catla catla) fingerlings and its amelioration through dietary vitamin C. The deltamethrin exposed fishes were fed with different levels of supplemented vitamin C such as 50, 250, 500 and 1000 mg/kg diet to see its ameliorating effect by assaying hematological parameters viz. total erythrocyte count (TEC), total leukocyte count (TLC), hemoglobin content (Hb), total serum protein, albumin, globulin, albumin–globulin ratio and biochemical parameters such as lactate dehydrogenase (LDH), acetylcholine esterase (AChE), alanine amino transferase (ALT), aspartate amino transferase (AST), total adenosine triphosphatase (ATPase), magnesium adenosine triphosphatase (Mg²⁺-ATPase) and sodium potassium adenosine triphosphatase (Na⁺, K⁺-ATPase) activities. The finding of this study showed that deltamethrin had negative effect on the hematological and biochemical parameters of Catla catla. The experimental group, which was exposed to deltamethrin and fed with normal diet showed significantly lower values (P ? 0.05) of all parameters studied except ALT activity. This might be due to possible disruption of hematopoiesis and proteosynthesis. However, the fish fed with varied concentration of vitamin C in diets neutralized the toxic effect of deltamethrin, as evidenced by significantly lowered hematological and biochemical response. Vitamin C @ 1000 mg/kg diet was the most effective in amelioration of harmful effect of deltamethrin on hematological and biochemical parameters of catla fingerlings. The result suggests that vitamin C can be effectively used to neutralize the toxic effect of deltamethrin on catla.     

λ-cyhalothrin and cypermethrin induced in vivo alterations in the activity of acetylcholinesterase in a freshwater fish, Channa punctatus (Bloch)

In the present study, the in vivo effects of λ-cyhalothrin and cypermethrin on the activity of acetylcholinesterase (AChE, EC 3.1.1.7) were evaluated for 96 h in brain, muscle and gills of Channa punctatus. Both compounds exhibited tissue specific as well as dose dependent decrease in the activity of AChE. The treated fish showed a significant decrease in the activity of AChE in brain and a lesser inhibition in muscle and gills in response to the increasing concentrations of λ-cyhalothrin as well as cypermethrin. Our results indicated that the brain was the main target organ for both insecticides, followed by muscle and gills, as determined by AChE inhibition study. However, these organs showed variations in the degree of AChE inhibition for separate treatments of both insecticides. The λ-cyhalothrin was a more potent AChE inhibitor as compared to cypermethrin. These findings indicated that apart from the established mechanism of delayed closure of sodium ion channels, these pyrethroids inhibit the activity of AChE in C. punctatus which could further aggravate their neurotoxic effects.     

Acute toxicity and bioconcentration of pyrimorph in zebrafish,Brachydanio rerio

BACKGROUND: Pyrimorph is a novel fungicide being developed in China that shows high antifungal activity against diseases caused by Phytophthora infestans, Phytophthora capsici, Rhizoctonia solani, Peronophythora litchi and Pseudoperonospora cubensis. Until now, no information on the toxicity of pyrimorph to untargeted organisms has been reported. To assess the potential environmental impacts of pyrimorph in fish, the acute toxicity and bioconcentration of pyrimorph in zebrafish were studied in this paper. RESULTS: When tested by the semi‐static method, the 48, 72 and 96 h median lethal concentration (LC₅₀) values of pyrimorph to zebrafish were 24.33, 22.61 and 19.79 mg L^?1 respectively. To study the bioconcentration of pyrimorph in zebrafish, the fish were exposed to sublethal concentrations of pyrimorph (2.00 and 0.25 mg L^?1) for 192 h, a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method was applied to extract pyrimorph from samples and the residues of pyrimorph in the water and fish were determined by high‐performance liquid chromatography (HPLC). The highest bioconcentration factor (BCF) of pyrimorph in the fish was 1.07 × 10² (144 h) and 23.1 (96 h) after exposure to 2.00 and 0.25 mg L^?1 of pyrimorph respectively. CONCLUSIONS: The novel fungicide pyrimorph has low toxicity to zebrafish; however, it showed medium BCF to zebrafish. Therefore, more attention should be paid to the residue of pyrimorph in fish, as well as to its long‐term ecological effects. Copyright © 2011 Society of Chemical Industry     

六种农药对两种果蝇成虫室内毒力和主要解毒酶活性的影响

为明确田间常用农药对伊米果蝇Drosophila immigrans和海德氏果蝇D. hydei的毒力和解毒机制,采用药膜法在室内测定6种田间常用农药原药对2种果蝇实验种群成虫的LC_(10)、LC_(20)和LC_(50),并研究其中3种农药的亚致死剂量(LC_(10)、LC_(20))对果蝇谷胱甘肽S-转移酶(GST)、羧酸酯酶(CarE)、乙酰胆碱酯酶(AchE)3种主要解毒酶活性的影响。结果表明,乙基多杀菌素对伊米果蝇的毒力最大,LC_(10)、LC_(20)和LC_(50)分别为0.29、0.51和1.51 mg/L;甲维盐对海德氏果蝇的毒力最大,LC_(10)、LC_(20)和LC_(50)分别为0.14、0.36和2.09 mg/L;吡虫啉对2种果蝇的毒力均最低。不同亚致死浓度的乙基多杀菌素处理伊米果蝇24 h后,CarE和AchE活性均显著高于对照,而GST活性在低浓度时显著高于对照;高浓度甲维盐仅对海德氏果蝇AchE活性有显著抑制作用;吡虫啉可抑制伊米果蝇AchE和海德氏果蝇CarE活性。表明伊米果蝇和海德氏果蝇可通过改变3种解毒酶的活性来防御杀虫剂对其造成的影响。     

Inhibition of Na-K-ATPase in different tissues of freshwater fish Channa punctatus (Bloch) exposed to monocrotophos

Freshwater fish, Channa punctatus, commonly known as the snakehead fish, was exposed to two sublethal concentrations (0.96 and 1.86 mg/L) (selected on the basis of 1/20 and 1/10 of 96 h LC₅₀ value) of monocrotophos for two exposure periods (15 and 60 days). Effects of monocrotophos on Na⁺, K⁺-ATPase in liver, kidney, muscle, intestine, brain, heart and gills were determined. Results indicate that Na⁺, K⁺-ATPase activity in tissues decreased as concentration of monocrotophos and exposure period increased. Monocrotophos induced significant inhibitory effects on the Na⁺, K⁺-ATPase activity of C. punctatus, ranging from gills (70%) > Kidney (63%) > brain (57%) > intestine (52%) > liver (50%) > muscle (47%) > heart (44%) inhibition at a sublethal concentration of 0.96 mg/L. Significant inhibition was detected in Na⁺, K⁺-ATPase activity, ranging from gills (90%) > heart (78%) > kidney (78%) > muscle (74%) > intestine (71%) > brain (67%) > liver (63%) at sublethal concentration of 1.86 mg/L. After subacute exposure (15 days) only gills and brain showed significant inhibition after higher concentration (1.86 mg/L). However, it is evident that exposure duration is more important than dose in the inhibition of the activity of enzyme. At lower concentration initial stimulation of the activity of Na⁺, K⁺-ATPase activity was also noticed. It is suggested that the inhibition of the ATPase by monocrotophos blocked the active transport system of the gill epithelial as well as chloride cells, glomerular and epithelial cells of the tubules and thus altered the osmoregulatory mechanism of the fish. In fact, the impairment of the activity of enzymes which carry out key physiological roles could cause alterations of the physiology of the whole organism.     

Botanical pesticide, azadirachtin attenuates blood electrolytes of a freshwater catfish Heteropneustes fossilis

The present study was aimed to investigate the effects of purified neem extract azadirachtin on the blood electrolytes of Heteropneustes fossilis for short- and long-term. In short-term exposure the fish were subjected to 0.8 (i.e. 80%) of 96 h LC₅₀ value of azadirachtin (41.89 mg L⁻¹) for 96 h. In long-term exposure the experiment was performed for 28 days by using 0.2 (i.e. 20%) of 96 h LC₅₀ value of azadirachtin (10.47 mg L⁻¹). Fish were sacrificed (anaesthesized with MS 222) from control and experimental (azadirachtin) groups after 24, 48, 72, and 96 h in short-term exposure and after 7, 14, 21, and 28 days in long-term experiment. Blood samples were analyzed for calcium and inorganic phosphate levels. Acute exposure of azadirachtin caused a progressive decrease in the serum calcium levels after 48 h in fish H. fossilis which persists till the close of the experiment (96 h). The serum inorganic phosphate levels remained unaffected till 72 h in the azadirachtin exposed fish. After 96 h the levels exhibit a decrease. Chronic azadirachtin treatment caused a decrease in serum calcium levels at day 14. This decrease continued till the end of the experiment. The serum phosphate level of the azadirachtin treated fish decreased on day 14 and 21. However, on day 28 the levels were close to the normal values.     

Effect of a paired mixture of aldrin and formothion on carbohydrate metabolism in a fish, Heteropneustes fossilis

Exposure of the Indian catfish (Heteropneustes fossilis) to a high sublethal concentration, 0.114 ppm (0.8 of the 96-hr LC₅₀) of a mixture of aldrin and formothion, added in a one-to-one ratio, for 3, 6, 12, 48, and 96 hr affected carbohydrate metabolism. Muscle glycogen decreased significantly at 6 and 48 hr; hepatic glycogen content declined at 3, 6, 12, and 48 hr in exposed fish. Blood glucose levels in fish were significantly decreased at 3, 12, 48, and 96 hr. Mean value of blood pyruvate was significantly depressed at 3 hr. Blood lactate levels were elevated at 3, 6, 12, and 96 hr in pesticide-treated fish. The observed effects of the mixture of aldrin and formothion on carbohydrate metabolism in fish could prove useful as a rapid method for evaluating toxicity of pesticides and other toxicants.     

Carbofuran-induced biochemical changes in Clarias batrachus

The effect of carbofuran, an organo-carbamate pesticide, upon the level of protein as well as the activity of lactate dehydrogenase (EC 1.1.1.28, LDH) was studied by exposing the teleost fish, Clarias batrachus, to different subacute con-centrations (0·01 and 0·02 mg litre^-1) for 96 h and 15 days. The results showed a drastic decrease in the protein content in different body organs of the fish. The pesticide also caused a significant decrease in the level of activity of LDH in different body tissues of the fish, the effect being more pronounced in the gills, muscle, brain and liver than in kidney and heart. The decrease in protein content and the activity of LDH in fish tissues was more marked at the higher concentration of the pesticide for the longer duration of treatment. The results suggested that carbofuran has an effect at very low concentration (compared to its LC₅₀ value) possibly at the level of protein metabolism, and also inhibits the activity of LDH, the terminal glycolytic enzyme. © 1998 SCI     

Oxidative stress and locomotor behaviour response as biomarkers for assessing recovery status of mosquito fish, Gambusia affinis after lethal effect of an organophosphate pesticide, monocrotophos

Recovery study was performed at regular intervals to establish the time course of 50% and 100% recovery in neurotransmitter enzyme (acetylcholinesterase, AChE, EC 3.1.1.7) and locomotor behaviour response of mosquito fish, Gambusia affinis exposed to lethal concentration (20.49 mg L⁻¹) of an organophosphorous pesticide, monocrotophos (MCP) for 96 h. In vitro AChE activity studies indicated that MCP could cause 50% inhibition (I₅₀) at 10.2 × 10⁻⁵ M. A positive correlation was observed between brain AChE activity and swimming speed during the recovery study. Also, the recovery response of the antioxidant enzymes superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6) and glutathione reductase (GR, EC 1.6.4.2) as well as lipid peroxidation (LPO) as biomarkers of oxidative stress were assessed in viscera of G. affinis. The results showed that the MCP besides its inhibitory effect on target enzyme AChE activity and induction in antioxidant enzyme activities as a characteristic of oxidative stress, which can be used as biomarkers in the pesticide contaminated aquatic streams.     

Comparison of acetylcholinesterase from three field populations of Liposcelis paeta Pearman (Psocoptera: Liposcelididae): Implications of insecticide resistance

The toxicological and biochemical characteristics of acetylcholinesterases (AChE) in Liposcelis paeta Pearman were investigated in three field populations collected from Nanyang city of Henan Province (NY), Wuzhou (WZ) and Hezhou (HZ) Cities of Guangxi Province, China. The result of bioassay showed that the LC_50s of the NY (281.4802 mg/m²) and the WZ (285.0655 mg/m²) to dichlorvos were 1.156-fold and 1.171-fold higher than that of the HZ (243.5197 mg/m²), respectively. Compared to NY population, the activity per insect and the specific activity of AChE in WZ and HZ populations were significantly higher, and significant kinetic differences among the three populations were also observed. The apparent Michaelis–Menten constant (K_m) for acetylthiocholine iodide (ATChI) was obviously lower in NY than that in WZ and HZ populations, indicating a higher affinity to the substrate ATChI in the NY population. The affinity to the substrate ATChI between WZ and HZ population was also significantly different. As for V_max, the values of WZ and HZ populations were significantly greater when compared to that for NY population, suggesting a possible over expression of AChE in the former two populations. The inhibition studies of AChE indicated that paraoxon-ethyl, demeton-S-methyl, carbaryl, and eserine all possessed some inhibitory effects on AChE in L. paeta. The results of I_50S suggested that when compared to the other two populations, while AChE from HZ population was less sensitive to paraoxon-ethyl and demeton-S-methyl. The contradiction with the result of the bioassay might be due to the different insecticides used in the bioassay. Although both carbaryl and eserine had excellent inhibitory effects, there was no significant difference among the three populations. The statistical analysis of the bimolecular rate constants (k_i) was consistent with the above situation that carbamates expressed remarkable inhibitory effects. It was noticeable that NY population was most sensitive to carbaryl while least to eserine. The differences in AChE among three populations may attribute to the difference in control practices for psocids between Henan and Guangxi Provinces.     

多杀菌素亚致死浓度对小菜蛾解毒酶系活力的影响

采用多杀菌素亚致死浓度,以浸叶法分别处理小菜蛾Plutella xylostella (L.)敏感种群(SS)和亚致死选育种群 的3龄幼虫,分别测定饲喂处理6、12、24、48和72 h后小菜蛾体内羧酸酯酶(CarE)、谷胱甘肽S-转移酶(GST) 和多功能氧化酶(MFOs)的活性,分析了酶活性的变化动态。结果表明,SS种群小菜蛾CarE的活性在不同时间段波动较大,经多杀菌素处理后,开始时段比活力增加,随着处理时间的延长,比活力逐渐被抑制,Sub-SS种群的GarE活力高于SS种群;多杀菌素对GST具有明显的诱导作用,亚致死浓度处理后GSTs比活力呈上升趋势,且具有一定的时间效应;对细胞色素P450酶系的O-脱甲基酶活性具有明显的抑制作用,多杀菌素亚致死浓度连续处理5代后,该酶活性更低。     

Being exposed to low concentrations of pirimiphos-methyl and chlorfenapyr has detrimental effects on the mobility of Trogoderma granarium

BACKGROUND

Sublethal effects of insecticides may negatively affect several biological and behavioral traits of insects. The lethal effects of pirimiphos-methyl and chlorfenapyr have been previously showed on Trogoderma granarium, but little knowledge is available about their sublethal effects at low concentrations on both sexes. Herein, the sublethal effects of pirimiphos-methyl and chlorfenapyr on the mobility of T. granarium males and females were investigated.

RESULTS

Lethal concentration (LC) values of pirimiphos-methyl and chlorfenapyr were lower for T. granarium females than males. LC values on males were LC₁₀ = 0.000788 and 0.00139 mg active ingredient (a.i.) cm⁻², LC₃₀ = 0.00350 and 0.00535 mg a.i. cm⁻², and LC₅₀ = 0.00986 and 0.0136 mg a.i. cm⁻² for pirimiphos-methyl and chlorfenapyr respectively. LC on females were LC₁₀ = 0.000704 and 0.00110 mg a.i. cm⁻², LC₃₀ = 0.00323 and 0.00428 mg a.i. cm⁻², and LC₅₀ = 0.00925 and 0.0110 mg a.i. cm⁻² for pirimiphos-methyl and chlorfenapyr respectively. The walking duration of beetles exposed to LC₃₀ of pirimiphos-methyl was significantly lower than the individuals exposed to LC₁₀ and LC₃₀ of both insecticides and control ones. Pirimiphos-methyl LC₃₀-exposed males remained more time on their back (101.7 s) than females (46.9 s), while the latter stayed immobile longer than males (381.7 s versus 371.9 s). The highest speed was recorded for control beetles (14.17 mm s⁻¹ females vs. 12.44 mm s⁻¹ males), while the lowest speed was observed in pirimiphos-methyl LC₃₀-treated males (8.36 mm s⁻¹) and females (9.66 mm s⁻¹).

CONCLUSIONS

Overall, males and females exposed to low concentrations of pirimiphos-methyl and chlorfenapyr showed reduced motility. This knowledge can be exploited further to unlock behavioral effects of insecticides for effective pest management programs in warehouses. © 2023 Society of Chemical Industry.