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The melon aphid, Aphis gossypii Glover (Hemiptera: Aphididae), is one of the most important pests of agricultural products in Iran. In this study, susceptibility of melon aphid that collected from seven regions (Yazd, Varamin, Mohammadshahr, Esfehan, Karaj, Hashtgerd and Ramsar) was compared to pirimicarb and malathion after 24 hours in 2009. Bioassay experiments on adults were carried out by using leaf dipping method on squash (Cucurbita pepo) leaf in different concentrations of insecticides in laboratory conditions (25 ± 0.2 ºC, 60 ± 5%, 16: 8 [L: D] h). Control treatment was dipped in distilled water. Each test was replicated three times. The results showed that LC₅₀ values of malathion for Ramsar, Karaj, Mohammadshahr, Hashtgerd, Varamin, Esfehan, and Yazd populations were 162.99, 159.19, 117.94, 79.96, 38.81, 36.32, and 20.25 ppm, respectively. Also, LC₅₀ values of pirimicarb for Yazd, Mohammadshahr, Kararj, Hashtgerd, Ramsar, Esfehan, and Varamin populations were 1414.16, 1359.34, 1057.62, 970.33, 881.87, 806.14, and 601.98 ppm, respectively. According to results, aphids of Varamin and Yazd populations had the most susceptibility to pirimicarb and malathion, respectively. Also, aphids of Yazd and Ramsar populations had the least susceptibility to pirimicarb and malathion, respectively. Regarding the fact that Yazd and Ramsar populations had the least susceptibility to pirimicarb and malathion, respectively, there is a possibility that melon aphids in these regions are susceptible to other organophosphate and carbamate (similar mode of action) pesticides. Therefore, in the pest management program, careful chemical control measures for melon aphid in these regions is recommended.  

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Toxicity and LC₅₀ 96-h of Malathion on the Caspian common carp fingerlings, Cyprinuscarpio, and its effects on some blood indices, including hematocrit, glucose, cholesterol and total protein content, were investigated. The median lethal concentration, the lowest effective concentration and the maximum allowable concentration were found to be 1.3, 0.646 and 0.13 mg.L^-1, respectively. Based on the LC₅₀ finding, Malathion can be regarded as “moderately toxic” for this fish.  Significant differences between the hematocrit, glucose, and cholesterol among treatments were evident, but no significant difference in the total protein of blood plasma was observed. The hematocrit level in the control group was lower than the other groups. The lowest levels of cholesterol and glucose were observed in 0.5 mg/L, and the maximum levels were found in 2.5 and 2 mg/L, respectively. Therefore, malathion which is supposed to be ineffective for non-target species at allowable concentrations, can lead to their blood indicies responses and bio-damages.

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Bactrocera zonata (Saunders) (Diptera: Tephritidae), an extremely aggressive species infesting some of the main commercial fruit and vegetables, has been subjected to a diverse array of control approaches. In the current study, performance of various Methyl Eugenol (ME) dispensers in combination with an organophosphate insecticide, Malathion, were evaluated against B. zonata in two consecutive years (2006-2007). Treatments efficacy was studied in various months using the criterion of trapped B. zonata flies. ANOVA revealed a significant difference among various application methods in both fruit infestation rate and capture of B. zonata flies. So that impregnation of chipboard block in ME caused the lowest B. zonata infestation and the highest B. zonata capturing values in both years. Population fluctuation study revealed a major peak for B. zonata in September i.e., mango ripening time. According to our results, it could be suggested that chipboard dispenser is the best application method as attractant in bait trap which exhibits more potent and longer lasting activity.  

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Aims: Malathion is one of the agricultural organophosphate pesticides used in agriculture that may be found in aquaculture centers. The aim of this study was to investigate the effects of different levels of dietary vitamin C on improving the situation of growth, digestive enzymes activity and blood stress factors of Nile Tilapia (Oreochromis Niloticus) under sub-lethal toxicity of malathion.

Materials & Methods: In this experimental study, 180 Nile tilapia with weight average of 12.5±5g were subjected to 25% concentrations of Lc50 96h of malathion for 28 days and during this period, the fishes were fed with different levels of vitamin C (0, 300, 600, and 900mg/kg of feed). Data were analyzed by Duncan's new multiple range test and one-way analysis of variance through SPSS 24 software.

Findings: The weight gain and specific growth rate of fish fed by the highest vitamin level (900mg/kg of feed) were significantly higher than other groups (p<0.05), while the feed conversion ratio in the fish under mentioned treatment significantly decreased compared to other treatments. Trypsin and chymotrypsin digestive enzyme activities were significantly increased in treatments of 600 and 900mg/kg vitamin C in diet, respectively. The activity of other enzymes at different concentrations of vitamin C in the diet did not show a significant difference (p>0.05). Blood glucose level was significantly higher in control treatment in comparison to the other treatments.

Conclusion: Vitamin C as an anti-stress agent reduces the stress in Nile tilapia subjected by Malathion pesticides and improve the metabolic status and growth performance of Nile tilapia.

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Malathion and diazinon are widely used organophosphate pesticides in the agriculture fields, especially in the north provinces of Iran. In the current study, lethal concentrations of diazinon and malathion were determined based on big head carp calculated death rates at 24, 48, 72 and 96 hours using probit analysis. Then, in a separate experiment and according to the obtained LC₅₀, the effects of these toxins on fish hematological parameters was evaluated in which fish were disturbed in 10 treatments with 3 replicates (4 different doses of diazinon, 4 different doses of malathion and 1 control for each toxin) for 7 days. Fish were exposed to different sub-lethal concentrations of each toxin (12.5, 25, 37.5 and 75% of lethal concentration (LC50 96h). After 7 days, blood samples were collected and hematological parameters including hematocrit, hemoglobin, red blood cells count, the total number of white blood cells and white blood cell differential count (the percentage of lymphocytes, monocytes, neutrophils and eosinophils) were examined. The results of acute toxicity test showed that diazinon is more toxic to big head carp compared to malathion. Also, hematological studies of big head carp exposed to diazinon showed a significant reduction in red blood cells and white blood cells with increasing toxin concentration. Meanwhile, the percentage of neutrophils remarkably increased while lymphocytes significantly decreased along with increasing the concentration of diazinon.

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The use of chemical compounds is a very simple and effective way to protect agricultural products, against pests. Increasing the unplanned use of these pesticides is a concern, because the pesticides residue in fruits and vegetables can lead to very dangerous side effects in humans. Olive is one of the most useful and consuming fruits in the Iranian community that can be used as pickled olive. Therefore, in this study, fermentation ability to reduce residues of two commonly used pesticides, Malathion and Diazinon studied, and their changes due to product acidity, pH and salt content during the preparation and fermentation processes were meassured. The results showed that washing and debittering operations reduced Malathion and Diazinon to 73.59 and 93.38%, respectively. However, after 20 days fermentation, their reduction was 63.68% and 69.57%, and after 40 days, at the end of production, this decrease was approximately 90.5% and 97.98%, respectively. The residue of Malathion pesticide was significantly different in fermentation days; 1, 10 and 20 (P<0.05), while the mean value for Diazinon was not significant. Overall, the results showed that the fermentation process had a significant effect on Malathion residue (P<0.05) but did not affect Diazinon residue. Also, fermentation had a significant effect on the percentage of salt, pH and acidity (P<0.05). At the end of the fermentation process, no mould growing was observed, but the yeast grow was showed (CFU/g 1450), much lower than the number that could affect the quality of the product. Generally, the fermentation process effectively reduced the amount of residual pesticides, and the operations carried out in the production of pickled olives are more effective to reduce the amount of pesticide residues than the fermentation process itself.

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Water hardness can negatively affect the efficiency of pesticides. This study aimed to determine the effect of water hardness and adjuvants added to spray solution on the efficiency of insecticides. Three insecticides, namely, malathion, acetamiprid, and spiromesifen, were mixed in well water samples at 1,869, 645, and 265 mg L^-1 hardness, standard, and deionized water, and applied against the second instar nymph of Bemisia tabaci using leaf dip method. In another experiment, Zero-7 at 150 ppm and Arkan at 180 ppm as additives were added to water with 1869 and 645 mg L^-1 hardness, separately. LC₅₀ values showed that the toxicity of malathion, acetamiprid, and spiromesifen was 40, 157, and 84 times less in hard water (1,869 mg L^-1 hardness) than deionized water. The efficacy of malathion, acetamiprid, and spiromesifen was 13, 65, and 39 times less when they were diluted in water with 645 mg L^-1 hardness than deionized water. Malathion provided 37.28 and 18.59% greater toxicity when applied in hard water containing Zero-7 and Arkan than water without the adjuvants. The efficacy of acetamiprid was, respectively, 16.93 and 18.68% greater when it was applied in hard water containing Zero-7 and Arkan compared to water without the additives. Zero-7 and Arkan in hard water enhanced the efficacy of spiromesifen by 10.26 and 13.68% compared to water without adjuvants. Generally, the toxicity of the insecticides on B. tabaci was considerably reduced at the highest levels of water hardness. In contrast, adjuvants overcame the antagonistic effects of cations in hard water.