Technical Malathion Research Articles

Permethrin and malathion LD90 values for Culex quinquefasciatus vary with topical application site.

Prior research in multiple insect species has demonstrated that insecticide-induced mortality varies according to the body region exposed on the insect. This variation has been demonstrated in Culex quinquefasciatus Say (Diptera: Culicidae), but has not been quantified using dose-response curves. Applications of technical permethrin or malathion to one of three body regions on Cx. quinquefasciatus resulted in dose-response curves that were not equivalent to one another. The generated LD90 values and curves for each body region were compared with previously reported LD values for analogous sites in several mosquito species, specifically the mesothorax. Based on the present results, the permethrin and malathion LD50 and LD90 concentrations required for droplets impinging on the abdomen and mesothorax of Cx. quinquefasciatus when applied through ground-based spray systems utilized by mosquito control programmes were calculated.

Chemoenzymatic resolution of rac-malathion

Malathion, diethyl 2-[(dimethoxyphosphorothioyl)sulfanyl]butanedioate, is an organophosphate used to control insect pests. Malathion contains a diethyl succinate moiety that is a known functional group susceptible to desymmetrizing enzymes such as esterases that selectively react with a single enantiomer. Purified rac-malathion was subjected to hydrolysis at the diethyl succinate moiety of malathion under various conditions using wild type pig liver esterase to form (S)-malathion (12% ee) and ∼3:2 mixture of α- and β-monoacids of (R)-malathion. Technical malathion could not be enriched due to the presence of esterase inhibitors. Further investigation of this resolution using a panel of six PLE isoenzymes also demonstrated the formation of (S)-malathion, however, an improvement of up to 56% ee was obtained.

Detection of O,O,S-trimethyl phosphorodithioate, an impurity in phenthoate (PAP), in komatsuna

An unknown peak (peak A) was detected in a mass chromatogram of komatsuna extract containing a high concentration of phenthoate (PAP), and it was considered to be O,O,S-trimethyl phosphorodithioate (OOS). Although it is generally known that OOS exists as an impurity in technical malathion and PAP, it has not been reported that OOS is present in crops. Since an OOS standard is not commercially available, OOS was separated and purified from commercial emulsifiable malathion. Peak A was confirmed to be OOS by GC/MS using the purified OOS. The concentration of OOS was estimated to be 0.02 microgram/g. It is supposed that OOS was detected in crops because they contained a high concentration of PAP residue.

Toxicity of carbaryl and malathion to two federally endangered fishes, as estimated by regression and Anova

AbstractToxicity of technical carbaryl, Sevin®‐4‐Oil, and technical malathion to federally endangered Colorado squawfish (Ptychocheilus lucius) and bonytail (Gila elegans) was estimated by 4‐d renewal‐acute and 32‐d early life‐stage (ELS) tests. Median lethal concentrations were estimated by probit analysis. Effect concentrations for ELS tests were estimated by ANOVA and an alternative procedure using a linear‐plateau regression model. Linear‐plateau regression estimated a threshold concentration above which toxic effects began to occur. Median lethal concentrations and 95% confidence limits (in parentheses) for carbaryl, Sevin‐4‐Oil, and malathion were 1.31 (1.23, 1.40), 3.18 (2.87, 3.52), and 9.14 mg/L (8.36, 10.0) for Colorado squawfish and 2.02 (1.78, 2.25), 3.31 (3.06, 3.55), and 15.3 mg/L (14.4, 16.4) for bonytail. NOECs for Colorado squawfish were 445 μg/L carbaryl and 1,680 μg/L malathion. The NOECs for bonytail were 650 μg/L carbaryl and 990 μg/L malathion. Threshold concentrations for Colorado squawfish in ELS tests were 364 μg/L carbaryl and 455 μg/L malathion. Threshold concentrations for bonytail were 217 μg/L carbaryl and 521 μg/L malathion. Estimates of effect concentrations from linear‐plateau regression were consistently lower than those estimated by hypothesis testing. Linear‐plateau regression models accounted for a significant amount of total variation and adequately described the observed concentration‐response relation.

Protection from O,O,S-trimethyl phosphorothioate-induced immune suppression.

Acute administration of nontoxic doses of an impurity in technical malathion, O,O,S-trimethyl phosphorothioate (OOS-TMP), was able to block the in vitro generation of cytotoxic T lymphocytes (CTL) to alloantigen and antibody-secreting cells (Ab) to sheep red blood cells (SRBC). The effects of an antagonist of the delayed toxicity and lung damage of OOS-TMP, O,O,O-trimethyl phosphorothionate (OOO-TMP), and pretreatment of tolerance-inducing doses of OOS-TMP on OOS-TMP-induced immune suppression were examined. Treatment groups included (A) acute administration of OOO-TMP, (B) coadministration of OOO-TMP with OOS-TMP (at concentrations which have been shown previously to block lung toxicity). (C) repeated (4 x on consecutive days) administration of OOS-TMP (which was shown previously to block a lung toxicity which occurs following a challenge with OOS-TMP) and (D) repeated administration of OOS-TMP followed by a challenge dose of OOS-TMP 24 h before death. There was no change in lymphoid organ size following any of these treatments. However, splenocytes from animals that were exposed to treatment regimes A, B and D had significantly elevated proliferative responses to mitogens concanavalin A (ConA) and lipopolysaccharide (LPS). The ability of splenocytes to generate an Ab response to SRBC was significantly elevated following treatment regime A and at the lower dose in treatment regime D. All other treatment protocols did not alter this immune parameter. There was no difference in the ability of splenocytes to generate a CTL response following these treatment regimes. In conclusion, the degree of protection from immune suppression by these treatments which have been shown to protect against lung toxicity varied with the sensitivity of the immune parameters to suppression by acute administration of OOS-TMP.

Effects of subacute administration of O, S, S-trimethyl phosphorodithioate on cellular and humoral immune response systems

The effects of 14-day treatment with low doses of O, S, S-trimethyl phosphorodithionate ( OSS-TMP), an impurity in technical malathion, on the generation of cell-mediated and humoral immune responses were examined in female C57BL/6 mice. At a dose of 2.0 mg/kg per day OSS-TMP, the generation of antibody-sectreting cells to sheep red blood cells, the generation of cytotoxic T lymphocytes (CTL) to alloantigen and the production of Interleukin-2 were elevated approximately 2–3 fold, while no changes were observed in the proliferative responses to the polyclonal activators, Concanavalin A, lipopolysaccharide, or phytohemagglutinin. In contrast, at 5.0 mg/kg per day OSS-TMP, both the CTL and specific antibody responses were suppressed, while all other immune parameters examined were unchanged. Data from cell separation and reconstitution experiments indicated that both T and B lymphocytes were affected by these treatment regimes. These data suggest that long-term exposure to low doses of OSS-TMP may enhance the ability of an animal to generate an immune response while higher doses of OSS-TMP may suppress the generation of an immune response.

Control of Grasshoppers on Rangeland with Cyfluthrin, Isofenfos, and Flucythrinate, 1981

Abstract Ground applications of 3 candidate insecticides were tested to determine their effectiveness in reducing grasshopper densities north of Lame Deer, MT during the summer of 1981. All tests were conducted on moderately infested (9.0-13.7 grasshoppers/sq yd), relatively flat rangeland. Each materia was applied in 8 fluid oz of water per acre in 30-foot swaths using a modified John Blue Low Volume Sprayer (John Blue Company, Huntsville, AL; mounted on a ¾ ton 4-wheel-drive truck. Each candidate was compared to a standard ULV treatment of 8 fluid oz of 95% technical malathion per acre, and to an untreated. The species listed above comprised 74, 19, 2, and 2% of the grasshopper infestation, respectively, with 35.1% being adults. Three other species each comprised less than 1% of the infestation. Mortality was determined at 1,3, and 7 days posttreatment by counting with a pointer the number of grasshoppers in 50 estimated one-sq-yd quadrats for 10-acre plots, or 25 estimated one-sq-yd quadrats for 2.5-acrt plots. The experimental design for cyfluthrin was 10-acre square plots of 3 rates replicated 4 times in a randomized complete block design. The highest dosage crystallized in a mixing container during application, so data for that dosage were obtained from only 2 replicates. In a separate test the experimental design for isofenfos and flucythrinate was 2.5-acre square plots of 2 rates and, replicated 2 times.

Control of Grasshoppers on Rangeland with Carbosulfan, 1980

Abstract The 4EC formulation of carbosulfan was applied in 1980 to 10-acre plots in 30-foot swaths with a modified John Blue Low Volume Sprayer (John Blue Company, Huntsville, AL) mounted on a ¾ ton 4-wheel-drive truck. Three dosages were applied, each in 8 fluid oz of water per acre, and were compared to a standard ULV treatment of 8 fluid oz of 95% technical malathion plus an untreated. All treatments were replicated 4 times in a randomized block design. Treatments were applied Jun 24 and 25, 9 miles NE of Melville, MT. The species listed above comprised 41, 25, 23, 4, 3, and 1.6 percent of the infestation, respectively, with 72% being adults. Three other species comprised less than 1.0 percent each of the infestation. Pretreatment densities ranged from 2.6 to 6.5/sq yd. Mortality was determined at 1,3, and 7 days posttreatment by counting with a pointer the number of grasshoppers in 50 estimated 1 sq yd quadrats per plot.

Effects of subchronic treatment with O,O,S-trimethyl phosphorothioate on cellular and humoral immune response systems

The effect of a 14-day treatment with low doses of O,O,S-Trimethyl phosphorothioate (OOS-TMP), an impurity in technical malathion, on the generation of cell-mediated and humoral immune responses was examined in female C57B1/6 mice. At a dose of 0.5 mg/kg/day OOS-TMP, the generation of antibody-secreting cells to sheep red blood cells (SRBC), the production of interleukin 2 (IL-2), and proliferative responses to the mitogens concanavalin A (Con A) and lipopolysaccharide (LPS) were elevated. In contrast, the cytotoxic T-lymphocyte (CTL) response to alloantigen was unchanged. At 5.0 mg/kg/day OOS-TMP, both the CTL and specific antibody response were unchanged, but all other immune parameters examined were elevated. Data from cell separation and reconstitution experiments indicated that both macrophages and B cells were affected by this treatment regime. These data suggest that long-term exposure to low amounts of OOS-TMP may enhance the ability of an animal to generate an immune response.

The effect of isomalathion and O,S,S-trimethyl phosphorodithioate on the in vivo metabolism of malathion in rats

Two organophosphorus impurities of technical malathion, isomalathion and O,S,S-trimethyl phosphorodithioate, were examined for their effects on the in vivo metabolism of malathion in rats. Both impurities were confirmed to be potent in vivo inhibitors of plasma, liver, and kidney malathion carboxylesterases at relatively low doses. Pretreatment of rats with these impurities followed by administration of [ 14C]malathion resulted in changes in the quantities of certain malathion metabolites excreted into the urine. Compared to the corn oil-pretreated control animals, the most notable change in the impurity-pretreated animals was in the decrease in the mount of malathion diacid excreted along with a commensurate increase in the amount of excreted malathion α monoacid. An increase in malaoxon metabolites in the urine of impurity-pretreated rats was indicated, suggesting that more malaoxon was originally produced in these animals.

Studies on organophosphorus impurities in technical malathion: Inhibition of carboxylesterases and the stability of isomalathion

Four organophosphorus esters found as impurities in technical malathion were synthesized, and their abilities to inhibit monomeric and oligomeric carboxylesterases from rabbit liver, as well as type I and type II esterases from porcine liver, were studied. The equilibrium dissociation constant ( K d ), phosphorylation constant ( k 2), and bimolecular rate constant ( k i ) were determined in the presence of substrate. Inhibition, as judged by the k i , was in the following order: isomalathion > O,S,S-trimethyl phosphorodithioate > O,O,S-trimethyl phosphorothioate > O,O,S-trimethyl phosphorodithioate. All of the k 2 values were relatively small, indicating that the k d values contribute most to the overall inhibitory power. Rabbit liver carboxylesterases are more sensitive to inhibition by isomalathion than porcine liver esterases, reflecting a species difference. Isomalathion undergoes nonenzymatic degradation in the presence of fluoride ions, producing diethyl thiomalate. A kinetic investigation of the nonenzymatic degradation of isomalathion was conducted, and reaction rate constants were determined in phosphate buffer at various molarities, temperatures, and pH values.

An impurity of malathion alters the morphology of rat lung bronchiolar epithelium

Oral administration of O, O, S-trimethyl phosphorothioate (OOS), an impurity in technical malathion, caused morphological changes in the bronchiolar epithelium of rat lungs. OOS-treated rat lungs had fewer but larger Clara (non-ciliated) cells than lungs from control rats given either corn oil or purified malathion. Moreover, lactate dehydrogenase (LDH) activity in bronchopulmonary lavage fluid was significantly higher in OOS than in control rats. We interpret these data to mean that OOS, and/or its metabolite(s) causes a lesion in the lung. Because of the widespread agricultural use of technical malathion, future work should address the significance of our findings and the possible toxic effect of OOS on lung tissue.

Enhanced Phytotoxicity of Bentazon with Organophosphate and Carbamate Insecticides

The organophosphate insecticides, malathion [S-1,2-di (ethoxycarbonyl)ethylO, O-dimethyl phosphorodithioate], parathion (O, O-diethylO-4-nitrophenyl phosphorothioate) and diazinon (O,O-diethylO-2-isopropyl-6-methylpyrimidin-4-yl phosphorothioate) combined with bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide], caused severe injury to soybean [Glycine max(L.) Merr. ‘Corsoy′] and navy bean (Phaseolus vulgarisL. 'Seafarer′). Postemergence tank – mixture applications of bentazon with organophosphate or carbamate insecticides, or soil-applied organophosphate insecticides prior to bentazon treatments, did not interact with bentazon to injure corn (Zea maysL. ‘Great Lakes Hybrid 4122′). Technical grade malathion interacted with bentazon to the same extent as formulated malathion. Combination treatments of malathion with bentazon resulted in the same degree of injury whether they were applied as tank mixtures or split applications 48 h apart.

Large-Scale Test of Control of Grasshoppers on Rangeland with Nosema locustae123

Nosema locustae Canning was applied to rangeland by aircraft at dosage rates of 2.1 × 109 and 2.1 × 108 spores per ha when the major grasshopper species, Melanoplus Sanguinipes (F.), were mostly 3rd instars. These treatments were compared with a standard rangeland insecticide treatment with 560 ml of 95% technical malathion per ha, and compared with no treatment. Each plot was 2,332 ha, and each treatment was replicated four times. The high level of N. locustae caused significant reductions in grasshopper densities during the season of treatment (1975). A panzootic among grasshoppers caused by the fungus Entomophthora grylli Fresenius occurred early in the second season and reduced the potential for expression of subsequent effects by N. locustae . Nevertheless, the high level caused significant reductions, and the low level appeared to cause slight but not significant reductions in grasshopper densities during the two subsequent seasons (1976 and 1977). Parasitism of grasshoppers by entomophagous flies and nematodes decreased sharply in malathion plots, but tended to increase in N. locustae and untreated plots.

Malathion for Control of Black Grass Bug, 1978

Abstract Malathion ULV concentrate was applied at 8, 6 and 3 fluid oz of technical material (91%)/acre to 40 acre plots replicated 4 times, and 2 fluid oz of technical material/acre was applied to a 100 acre plot near Llaves, NM from May 10 through 13, 1978. All plots had been reseeded with Crested Wheatgrass. All dosages except the 8 oz treatment were diluted with water (to emulsify the malathion Triton X - 190 was used at 20% of the volume of malathion). Six And 3 oz treatments were applied in 8 oz of fluid/acre while the oz treatment was applied in 16 oz of fluid/acre. All treatments were applied with a Cessna Ag-truck 188B aircraft at 40 psi through a standard Cessna hydraulic driver spray system. Eleven 8001 flat fan nozzles were used for the 8, 6 and 3 oz treatments and (15) 80015 flat fan nozzles were used for the 2 oz treatment. All nozzles were rotated 90° to the slip stream. Flight speed was 120 mph; flight height and swath width were 30 and 75 ft respectively. Malathion ULV concentrate was applied at 3 oz of technical malathion, 2% Triton X-190, and water in 8 oz of fluid/acre to 3000 acres of reseeded Crested Wheargrass ca 15 miles NE of McNary, Arizona on May 18, 1978. This treatment was applied with a Turbo Thrush aircraft at 40 psi using 8008 nozzles. Application speed was 140-150 mph; flight height and swath width were 50 ft and 100 ft, respectively. Results on 40 acre plots were assessed by counting live black grass bugs in 4 subsamples (5 sucks/subsample) per plot taken with a 1/2 foot diameter modified de-vac. Results on 100 acre and 3000 acre plots were assessed by counting live black grass bugs at 30 sample sites (5 sucks/site) within each plot. Samples were taken 1-2 days prior to treatment and 2 days and 7 days following treatment. Both species listed above were found in the New Mexico plots, only L.hesperius was present in the Arizona plot.

Identification and toxicological evaluation of impurities in technical malathion and fenthion.

Identification and toxicological evaluation of impurities in technical malathion and fenthion.

Ontrol of Grasshoppers on Rangeland With Bendiocarb, 1979

Abstract The 50% Flowable formulation was applied to 10-acre plots in 30-foot swaths with a modified John Blue Low Volume Sprayer (John Blue Company, Huntsville, AL) mounted on a 3/4 ton 4-wheel-drive truck. Three dosages were applied, each in 32 fluid ounces of water per acre, and were compared to a standard ULV treatment of 8 fluid oz of 95% technical malathion. All treatments were replicated three times in a randomized block design. Treatments were applied July 18-22 near Three Forks, Montana. The species listed above comprised 70,12,5,4,4, and 2 percent of the infestation, respectively, with only 7.5 percent being adults. Five other species comprised less than 1.0 percent each of the infestation. Prerreatments densities ranged from 1.6 to 5.2/sq yd. Mortality was determined at 3-, 5-, 7-, and 14-day intervals by counting with a pointer the number of grasshoppers in 50 estimated 1 sq yd quadrates per plot. Data for each interval were corrected by Abbott's formula for mortality in untreated control plots and were subjected to analyses of variance.

Evaluation of the modified colourimetric method for the determination of malathion: Its application to the analysis of malathion residues in water

The feasibility of the modified colourimetric method for the analysis of technical malathion has been demonstrated previously Clark & Qazi (1979). The present publication describes the development of a complete analytical scheme based on the same method for the analysis of aqueous solutions of malathion. In the work described, synthetic aqueous solutions containing malathion in ppm concentration have been analysed, but it is possible to extend the method to ppb level with a few minor modifications.

Health risks in ultra-low-volume (ULV) aerial spray of malathion for mosquito control.

A field study was undertaken to evaluate health risks in persons engaged in ultra-low-volume (ULV) aerial application of technical malathion for mosquito control. No specific toxicity signs and symptoms were observed except nausea and irritation of eyes in a few cases. Observations on the ChE activity has revealed a significant depression in plasma at the end of spray operation in labourers employed in loading and unloading of insecticide and in field workers. Red blood cells ChE activity was not affected in any group of subjects. At the end of spray operation the insecticide residue on the grass used as cattle feed were about 315 ppm, which are much above the permissible level. However, 4 days after the application normal levels of the insecticide residues were detected.

Inactivation of esterases by impurities isolated from technical malathion

Compounds previously identified as contaminants of technical malathion were found to diminish the activity of serum malathion carboxylesterase, liver malathion carboxylesterase, and serum cholinesterase in vitro and in vivo. The compounds tested were, in increasing order of potency, O,O,S-trimethyl phosphorodithioate, O,O,S-trimethyl phosphorothioate, O,S,S-trimethyl phosphorodithioate, and O,S-dimethyl S-(1,2-dicarboethoxy)ethyl phosphorodithioate. In vivo, the diminutions of serum esterase activity caused by these compounds were transient, with the exception of the diminutions caused by O,O,S-trimethyl phosphorothioate, which persisted for at least 54 hr. The most potent of these esterase inactivators, also known as isomalathion, is of particular interest as a possible contributor to an epidemic of malathion poisonings among malaria workers in Pakistan.