Comparisons of malathion susceptibility, target sensitivity, and detoxification enzyme activity in nine field populations of Oxya chinensis (Orthoptera: Acrididae)

The malathion susceptibility, acetylcholinesterase (AChE) sensitivity, and the activity of selected detoxification enzymes including general esterase (EST) and glutathione S-transferase (GST) were compared among field populations of the grasshopper Oxya chinensis (Thunberg) (Orthoptera: Acrididae) collected from nine regions of China. Bioassay results showed that these populations had various levels of the susceptibility to malathion with the LDo values ranging from 1.4- to 22.6-fold compared with the most susceptible population (Xiangyuan or XY). The Jinnan (JN) population seemed to be malathion resistant (22.6-fold), whereas other populations exhibited 1.4- to 6.8-fold reduced malathion susceptibility with a rank order of Changan > Baodi > Hanzhong > Xinxiang > Yinchuan > Beidagang > Jinyuan. It seemed that the observed malathion resistance in the JN population was attributed to at least two resistance mechanisms, including increased EST activity (2.2-fold) and reduced sensitivity of AChE to inhibition by malaoxon (4.6-fold) compared with those of the XY population. In contrast, differential malathion susceptibilities in other populations may be due to increased activities of certain detoxification enzymes (e.g., EST and GST), reduced sensitivity of AChE, or other factors, which were not consistent across the populations examined. Such differential susceptibilities to malathion were likely due to different population habitats (e.g., grasslands, rice [Oryza sativa L.]-producing regions) with very different insecticide application histories and pest management practices.     

Mechanisms of organophosphate resistance in a field population of oriental migratory locust, Locusta migratoria manilensis (Meyen)

The susceptibilities to three organophosphate (OP) insecticides (malathion, chlorpyrifos, and phoxim), responses to three metabolic synergists [triphenyl phosphate (TPP), piperonyl butoxide (PBO), and diethyl maleate (DEM)], activities of major detoxification enzymes [general esterases (ESTs), glutathione S-transferases (GSTs), and cytochrome P450 monooxygenases (P450s)], and sensitivity of the target enzyme acetylcholinesterase (AChE) were compared between a laboratory-susceptible strain (LS) and a field-resistant population (FR) of the oriental migratory locust, Locusta migratoria manilensis (Meyen). The FR was significantly resistant to malathion (57.5-fold), but marginally resistant to chlorpyrifos (5.4) and phoxim (2.9). The malathion resistance of the FR was significantly diminished by TPP (synergism ratio: 16.2) and DEM (3.3), but was unchanged by PBO. In contrast, none of these synergists significantly affected the toxicity of malathion in the LS. Biochemical studies indicated that EST and GST activities in the FR were 2.1- to 3.2-fold and 1.2- to 2.0-fold, respectively, higher than those in the LS, but there was no significant difference in P450 activity between the LS and FR. Furthermore, AChE from the FR showed 4.0-fold higher activity but was 3.2-, 2.2-, and 1.1-fold less sensitive to inhibition by malaoxon, chlorpyrifos-oxon, and phoxim, respectively, than that from the LS. All these results clearly indicated that the observed malathion resistance in the FR was conferred by multiple mechanisms, including increased detoxification by ESTs and GSTs, and increased activity and reduced sensitivity of AChE to OP inhibition.     

Time course variations of antioxidant enzyme activities and histopathology of gilthead seabream gills exposed to malathion

In a widely distributed and commercially important fish, gilthead seabream Sparus aurata L., we have studied sublethal effects of malathion in order to identify early warning bioindicators of exposure before irreversible damage occurs. To achieve this goal, groups of 10 juvenile specimens were exposed for 24, 48, 72 and 96 h to a sublethal concentration of malathion (0.4 mg/l). Another group was used as control. The activity of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) and histopathological features from exposed gills were assessed. It should also be mentioned that no mortality was observed during the whole experience. The activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) were altered significantly from 24 h onward (p<0.05). It is of interest to note that catalase activity was decreased after exposure instead of increasing as other antioxidant enzymes assessed. On the other hand, histopathological alterations of the gills were observed as early as at 48 h-exposure, but the most severe damage occurred at 96 h exposure. The evidence presented here, together with other data from the literature, unequivocally established oxidative-stress-inducing effects of malathion in gilthead seabream Sparus aurata. It is also concluded antioxidants employed (SOD, CAT and GPX) changed significantly a long time before histopathological alterations of gills became evident. Consequently, these antioxidant enzymes may be highly recommended as early-warning bioindicators of environmental pollution by malathion in the areas where it is proposed to be used in pest control activities.     

Effect of ULV malathion use in boll weevil (Coleoptera: Curculionidae) eradication on resistance in the tarnished plant bug (Heteroptera: Miridae)

Tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois), from regions 1, 2, and 3 of the boll weevil, Anthonomous grandis Boheman, eradication program in Mississippi were collected from wild hosts and tested for malathion resistance during the spring and fall of 2000 and 2001. Plant bugs were also tested in region 1 in late-July and October of 1999, just before and after multiple applications of ultra-low-volume (ULV) malathion were used for reproduction-diapause control of boll weevils in August and September. Regions 1 (north Delta), 2 (south Delta), and 3 (hills) began boll weevil eradication in 1999, 1998, and 1997, respectively. A glass-vial bioassay was used to determine resistance in plant bugs to malathion by comparing LC50 values against an LC50 value obtained for susceptible plant bugs. Comparison of the LC50 value obtained for plant bugs at a location in the spring was also made with the LC50 value obtained in the fall at the same location. After multiple applications of malathion made for reproduction-diapause boll weevil control in region 1 in August and September, malathion resistance increased by 4.9-, 6.5-, and 20.8-fold in plant bug populations from the three test locations. Results from testing bugs from all three eradication regions were similar. Malathion resistance usually increased significantly from spring to fall and then declined significantly from fall to spring of the next year. Despite reduced use of malathion in all three eradication regions for boll weevils in 2001, resistance to malathion in plant bugs still increased significantly from spring to fall at all test locations in regions 1 and 2 (the Delta). Malathion resistance did not increase significantly in plant bug populations in region 3 (the hills) in 2001 from spring to fall at three of four test locations in this year. Possible causes for the higher malathion resistance found in plant bugs in the Delta are discussed. Overall test results showed that the use of malathion in boll weevil eradication in cotton probably contributed to increases in resistance to malathion in plant bug populations in the eradication areas. However, the expression of this resistance was usually rapidly lost by spring of the following year. Boll weevil eradication did not seem to produce a permanent increase in the expression of malathion resistance in tarnished plant bug populations found in the eradication regions.     

Microbial cleavage of various organophosphorus insecticides.

Bacteria able to utilize Aspon, Azodrin, Dasanit, diazinon, malathion, Orthene, parathion, Trithion, dimethoate, Dylox, methyl parathion, and Vapona as sole phosphorus sources were isolated from soil and sewage. Individual isolates used from 3 to 10 of these insecticides as sole phosphorus sources. The extent of growth of two Pseudomonas strains in media containing diazinon and malathion was in the range expected from the amount of insecticide supplied, and their proliferation resulted in disappearance of the chemical. Resting cells of the pseudomonads derived from cultures grown on diazinon or malathion but not orthophosphate caused extensive destruction of these two organophosphates in the presence or absence of chloramphenicol. Extracts of the two bacteria derived from organophosphate-grown cultures catalyzed the disappearance of Aspon, Azodrin, Dasanit, diazinon, malathion, Orthene, parathion, and Trithion but not dimethoate, Dylox, methyl parathion, and Vapona. Results from gas chromatographic analysis suggested that the extracts formed dimethyl phosphate from azodrin, dimethyl phosphorodithioate from malathion, diethyl phosphorodithioate from Trithion, and diethyl phosphorothioate from Dasanit, diazinon, and parathion. Dimethyl phosphate, dimethyl phosphorothioate , dimethyl phosphorodithioate, diethyl phosphate, and diethyl phosphorothioate were not used by the pseudomonads as sole phosphorus sources.     

Microbial cleavage of various organophosphorus insecticides.

Bacteria able to utilize Aspon, Azodrin, Dasanit, diazinon, malathion, Orthene, parathion, Trithion, dimethoate, Dylox, methyl parathion, and Vapona as sole phosphorus sources were isolated from soil and sewage. Individual isolates used from 3 to 10 of these insecticides as sole phosphorus sources. The extent of growth of two Pseudomonas strains in media containing diazinon and malathion was in the range expected from the amount of insecticide supplied, and their proliferation resulted in disappearance of the chemical. Resting cells of the pseudomonads derived from cultures grown on diazinon or malathion but not orthophosphate caused extensive destruction of these two organophosphates in the presence or absence of chloramphenicol. Extracts of the two bacteria derived from organophosphate-grown cultures catalyzed the disappearance of Aspon, Azodrin, Dasanit, diazinon, malathion, Orthene, parathion, and Trithion but not dimethoate, Dylox, methyl parathion, and Vapona. Results from gas chromatographic analysis suggested that the extracts formed dimethyl phosphate from azodrin, dimethyl phosphorodithioate from malathion, diethyl phosphorodithioate from Trithion, and diethyl phosphorothioate from Dasanit, diazinon, and parathion. Dimethyl phosphate, dimethyl phosphorothioate , dimethyl phosphorodithioate, diethyl phosphate, and diethyl phosphorothioate were not used by the pseudomonads as sole phosphorus sources.     

Involvement of chromosomally-encoded genes in malathion utilization by Pseudomonas aeruginosa AA112

Malathion is an organophosphate insecticide that has been widely used for both domestic and commercial agricultural purposes. However, malathion has the potential to produce toxic effects in mammalian systems. In this study, Pseudomonas aeruginosa AA 112 which was isolated from soil using enrichment technique could utilize the malathion as a sole carbon source and a source of energy. Pseudomonas aeruginosa AA112 was able to grow in MSMPY medium containing 42.75 mg/ml malathion. However, the optimum concentration of malathion which supported the maximum bacterial growth was found to be 22. 8 mg/ml. Malathion was used as an initial source of energy and carbon when it was found without additional carbon sources (in MSM medium) while it was utilized as second source of energy and carbon in a nutrient-supplemented medium (in MSMPY medium). Moreover, lead acetate test indicated that malathion was first attacked at a sulphur site 1-2 hours after the start of incubation. TLC and IR analysis indicated that malathion was completely degraded into diethyl succinate, hydrogen sulphide and phosphates. Therefore a malathion degradation pathway was proporsed. The degradation of malathion is attributed to the genes located on the chromosome and at least three proteins of high molecular size might be involved in malathion utilization. Bacteria able to use malathion as a food source or metabolize its residues in the environment to inactive, less toxic, and harmless compounds, could be used in bioremediation of an environmental pollution caused by the pesticide.     

Alterations in esterases are associated with malathion resistance in Habrobracon hebetor (Hymenoptera: Braconidae)

Biochemical mechanisms of malathion resistance were investigated in a malathion-resistant strain of the parasitoid Habrobracon hebetor Say collected from a farm storage in Kansas. General esterase activities were significantly lower in the resistant strain compared with those in a susceptible strain. However, no significant differences were found in activities of malathion specific carboxylesterase (MCE), glutathione S-transferase and cytochrome P450 dependent O-demethylase activities, cytochrome P450 contents, and sensitivity of acetylcholinesterase to inhibition by malaoxon between the 2 strains. Because MCE was not elevated in the resistant strain, the weak malathion resistance in H. hebetor may result from a different mechanism compared with that hypothesized for some insect species in which reduced general esterase activity is accompanied by an elevated MCE. Decreased esterase activity in the resistant strain suggested that null alleles of some esterases were associated with the resistance. Indeed, E1 and E2, major esterases in the susceptible strain, were not present in the resistant strain on polyacrylamide gels that were stained for esterase activity using the model substrate 1-naphthyl acetate. In contrast, the activity of esterase E3 on the gels was much higher in the resistant strain as compared with that of the susceptible strain. These findings indicate that malathion resistance in H. hebetor is associated with both an increased activity of the esterase E3 and null alleles of the esterases E1 and E2.     

Mechanisms of resistance to malathion in the medfly Ceratitis capitata

Target site insensitivity and metabolic resistance mediated by esterases have been previously suggested to be involved in resistance to malathion in a field-derived strain (W) of Ceratitis capitata. In the present study, we have obtained the coding sequence for acetylcholinesterase (AChE) gene (Ccace) of C. capitata. An allele of Ccace carrying only a point mutation Gly328Ala (Torpedo numbering) adjacent to the glutamate of the catalytic triad was found in individuals of the W strain. Adult flies homozygotes for this mutant allele showed reduced AChE activity and less sensitivity to inhibition by malaoxon, showing that target site insensitivity is one of the factors of malathion resistance. In addition, all individuals from the resistant W strain showed reduced aliesterase activity, which has been associated with specific malathion resistance in higher Diptera. However, the alphaE7 gene (CcalphaE7), sequenced in susceptible and resistant individuals, did not carry any of the mutations associated with organophosphorus insecticide resistance in other Diptera. Another esterase mechanism, perhaps a carboxylesterase selective for malathion, in addition to mutant AChE, thus contributes to malathion resistance in C. capitata.     

Organophosphate Resistance in Aedes aegypti: Study from Dengue Hemorrhagic Fever Endemic Subdistrict in Riau,Indonesia

Background:Dengue hemorrhagic fever (DHF) is a significant health problem. The high number of cases requires preventions, including controlling the dengue vector, Aedes aegypti mosquito. One of the control methods is the use of insecticides containing organophosphate. This study aims to detect organophosphate resistance in Aedes aegypti from DHF endemic subdistrict, Riau, Indonesia by a sensitivity test of temephos and 5% malathion and measuring the activity of non-specific alpha and beta esterase enzymes.Methods:This observational study determined Aedes aegypti resistance from larvae to adult in one DHF endemic subdistrict in Riau, Indonesia. The bioassay was used for temephos sensitivity of Aedes aegypti larvae. The LC99 value was analyzed using probit and compared with the diagnostic value from WHO. The WHO susceptibility test was conducted to determine 5% malathion resistance from adult mosquitoes. The mortality of less than 90% was declared as resistant. Measurement of alpha and beta esterase levels used Lee''s microplate assay technique based on visual identification and absorbance value (AV).Results:The results showed that Aedes aegypti were resistant to temephos. It also showed that adult mosquitoes were resistant to 5% malathion. Based on the alpha esterase activity test, it was found that most of the mosquitoes showed very sensitive meanwhile, based on the beta esterase activity test, most of the mosquitoes were moderate resistance.Conclusion:This study suggests that Aedes aegypti population from DHF endemic subdistrict in Riau, Indonesia are indicated to develop resistance to organophosphate.Key Words: Aedes aegypti, Dengue Hemorrhagic fever, Organophosphate, Resistance     

Genetic variability in esterases and the insecticide resistance in brazilian strains of Oryzaephilus mercator and Oryzaephilus surinamensis (Coleoptera: Silvanidae)

Oryzaephilus mercator and O. surinamensis are stored grains and processed food pests, the latter being responsible for major economical losses. Polyacrylamide gel electrophoresis was used to analyse esterase patterns during insect development. Seven esterases, three cholinesterases, two carboxylesterases and two acetylesterases, were identified in O. mercator, one of which was proper to adults. Five esterases, of which four were cholinesterases, occurred in O. surinamensis. Strains of O. mercator and O. surinamensis were also exposed to malathion and chlorpyrifos-methyl. According to the LC50 estimates, OmLC-M and OmLA strains of O. mercator and OsLB strain of O. surinamensis were the most resistant to both insecticides. However, higher sensitivity to malathion and chlorpyrifos-methyl has also been verified in some of its esterases. Cholinesterases OmEST-1 and OsEST-5 seem to be involved in this resistance. These results suggest that organophosphate tolerance may be related to genetic variability in esterase isoenzymes.     

Study on the removal of pesticide in agricultural run off by granular activated carbon

In this batch study, the adsorption of malathion by using granular activated carbon with different parameters due to the particle size, dosage of carbons, as well as the initial concentration of malathion was investigated. Batch tests were carried out to determine the potential and the effectiveness of granular activated carbon (GAC) in removal of pesticide in agricultural run off. The granular activated carbon; coconut shell and palm shells were used and analyzed as the adsorbent material. The Langmuir and Freundlich adsorption isotherms models were applied to describe the characteristics of adsorption behavior. Equilibrium data fitted well with the Langmuir model and Freundlich model with maximum adsorption capacity of 909.1 mg/g. The results indicate that the GAC could be used to effectively adsorb pesticide (malathion) from agricultural runoff.     

N‐Acetyl‐cysteine mediated inhibition of spermatogonial cells apoptosis against malathion exposure in testicular tissue

Toxicological studies so far suggest that excessive use of malathion, an organophosphate insecticide, causes serious ill‐effects in mammalian reproductive physiology. The present study aims at assessing malathion‐induced toxicity in a dose‐ and time‐dependent manner with mitigating effects of N‐acetyl‐l ‐cysteine. The testicular germ cell viability was monitored using MTT assay, where NAC, being an antioxidant significantly reduced malathion‐induced toxicity by enhancing the frequency of cell viability. The histomorphological analysis showed that NAC successfully diminished several apoptotic features in testicular cells, induced by malathion. The differential EB/AO staining revealed a significant decline in the percentage of apoptosis after NAC supplementation. NAC also diminished the malathion‐induced DNA fragmentation along with significantly reduction in oxidative stress parameters causing decrease in lipid peroxidation and enhancement of ferric reducing antioxidant power within testicular germ cells. Thus, NAC mitigated the malathion‐induced toxicity, proving its potential in infertility treatment.     

Effects of a commercial malathion dip preparation on the cellular and humoral immune response of BALB/c mice

Because of the widespread use of malathion as a treatment for ectoparasitism, a study was undertaken to determine the effects of a malathion dip preparation on the BALB/c mouse immune system. Mice were treated with either 2% (recommended dosage) or 8% solutions of malathion or a water control. The cellular immune response was evaluated by in vitro exposure of lymphocytes to mitogens, and the humoral immune response was assessed by using an enzyme-linked immunosorbent assay (ELISA) to quantify antibody production against sheep red blood cells (SRBC). Responses to the mitogens and to the SRBC were not significantly different between 2% and 8% malathion treated and water treated mice. Results indicated that malathion did not affect these two aspects of the mouse immune system when used as a 2% or 8% dipping solution.     

Use of Malathion Against Ectoparasites on Lactating Cows

The clinical effect, residues in milk and toxicological properties of a non-commercial formulation of malathion used as an ectoparasitic agent on cattle were investigated. The results show that the malathion preparation has a desired clinical effect. The maximum concentration of malathion in milk after topical application of 5 g malathion was 0.054 μg/ml 4–6 h post-treatment, and declined to 0.005 and 0.002 μg/ml 24 and 48 h post-treatment, respectively. Totally 0.006–0.03 % of the applied dose was excreted in the milk. No toxic effect, measured as inhibition of the cholinesterases in erythrocytes and plasma, could be detected after therapeutic use of malathion. The pharmacokinetic evaluation after 2.5 g intravenous administration of malathion, indicated that the kinetics could probably be described by a multicompartment model.     

Use of meta‐analysis to predict degradation of carbaryl and malathion in freshwater for exposure assessment

Carbaryl (1‐naphthyl methylcarbamate) and malathion (diethyl mercaptosuccinate, S‐ester with O, O‐dimethyl phosphorodithioate) are insecticides used to control grasshopper infestations on rangeland. Insecticides used to control grasshopper infestations pose a hazard to aquatic organisms because although no‐spray buffer zones are observed around aquatic habitats, pesticide may be deposited by drift or mobilized from upland areas by runoff. A number of processes may affect the fate of carbaryl and malathion in the aquatic environment, but no method is available for estimating degradation over the range of conditions that occur in the field. We used results of published studies in meta‐analyses to estimate degradation models that predict half‐life of carbaryl and malathion in freshwater over temperature and pH ranges relevant to western grasshopper‐management programs. Estimated degradation models were:

In (half‐life carbaryl) = 24.3 ‐ 2.36(pH) ‐ 0.0788(t)

and In (half‐life malathion) = 5.98 + 2.84(pH) ‐ 0.326(pH ²) ‐ 0.202(t) + 0.00135(t ²)

where half‐life has units of hours, and temperature (t) has units °C. Both models accounted for a significant amount of total variation (P<0.0001) and had r²>0.97. Accuracy of these degradation models was evaluated by comparing predicted degradation of carbaryl and malathion to field and laboratory data. We suggest that use of these degradation models be restricted to conditions where water has 7 ≤. pH ≤. 10 for carbaryl, and 7 ≤ pH ≤ 8.2 for malathion.     

Malathion and pyrethroid resistance in Culex quinquefasciatus from Cuba: efficacy of pirimiphos-methyl in the presence of at least three resistance mechanisms

Use of malathion for mosquito control in Cuba for 7 years up to 1986 has selected for elevated non-specific esterase and altered acetylcholinesterase (AChE) resistance mechanisms in populations of the pest mosquito Culex quinquefasciatus Say. These mechanisms are still present in relatively high frequencies in the Havana area, despite the replacement of malathion by pyrethroid insecticides for the last 3 years in the mosquito control programme. Samples of Culex quinquefasciatus populations from within a 100 km radius of Havana had high levels of resistance to malathion and lower levels of resistance to propoxur, but there was little or no cross-resistance to the organophosphorus insecticide pirimiphos-methyl. Selection with malathion for twenty-two consecutive generations in the laboratory increased the level of malathion resistance to 1208-fold and propoxur level to 1002-fold, but the maximum level of pirimiphos-methyl resistance was only 11-fold. Pirimiphos-methyl is still operationally effective, despite the resistance mechanisms segregating, so this insecticide if used for control is unlikely to select either of the known resistance factors directly in the field population. Since 1986, pyrethroids have been used extensively, and low levels of pyrethroid resistance were detected in two of five field population samples tested. Malathion selection did not increase the level of pyrethroid resistance, which indicates that one or more distinct pyrethroid resistance factors are now being selected in the field populations of Culex quinquefasciatus.     

Submerged Macrophytes Mitigate Direct and Indirect Insecticide Effects in Freshwater Communities

Understanding how ecological interactions mitigate the impacts of perturbations such as pesticides in biological communities is an important basic and applied question for ecologists. In aquatic ecosystems, new evidence from microcosm experiments suggests that submerged macrophytes can buffer cladocerans from pulse exposures to the widely used insecticide malathion, and that mitigation increases with macrophyte density. However, whether these results scale up to more complex aquatic communities where ecological interactions such as competition can alter toxicity is unknown. Further, macrophyte abilities to mitigate different insecticide exposure scenarios (i.e. single versus repeated pulses) have never been tested. To address these gaps, we performed a factorial mesocosm experiment examining the influence of four macrophyte treatments (0, 10, 50, or 100 Elodea Canadensis shoots planted per mesocosm) crossed with three malathion exposure scenarios (no insecticide, single pulse, repeated pulses) on aquatic communities containing zooplankton, phytoplankton, periphyton, two snail species, and larval amphibians. In the absence of macrophytes, single malathion pulses caused short-term declines in cladoceran abundance followed by their rapid recovery, which precluded any indirect effects (i.e. trophic cascades). However, repeated malathion pulses caused cladoceran extinctions, resulting in persistent phytoplankton blooms and reduced abundance of one snail species. In contrast, with macrophytes present, even at low density, malathion had no effect on any taxa. We also discovered novel effects of macrophytes on the benthic food web. In the two highest macrophyte treatments, we observed trends of reduced periphyton biomass, decreased abundance of one snail species, and decreased amphibian time to and mass at metamorphosis. To our knowledge, this is the first evidence of negative submerged macrophyte effects on amphibians, a taxa of global conservation concern. Our findings suggest that facilitating macrophytes could be an important strategy for buffering freshwater communities from insecticides, though consideration of their impacts on animal species is necessary.     

Transformation of malathion by Lysinibacillus sp. isolated from soil

An axenic bacterial strain, Lysinibacillus sp. KB1, was isolated from malathion-contaminated soil. It tolerated malathion up to 0.15?% and, under aerobic conditions, utilized it as sole carbon source. 20?% malathion and 47?% malaoxon were degraded out of the initially provided malathion. Two metabolites, mal-monocarboxylic acid and mal-dicarboxylic acid, were detected within 7?days at 30?°C. Esterase activity of the strain was 240?±?2.5?U/ml after 7?days of growth. Sterilized soil mixed with malathion showed rapid degradation of malathion when inoculated with strain KB1 as compared to the uninoculated soil.     

Enantiomeric separation of malathion and malaoxon and the chiral residue analysis in food and environmental matrix

Malathion is a widely used chiral phosphorus insecticide, which has a more toxic chiral metabolite malaoxon. In this work, the enantiomers of malathion and malaoxon were separated by high-performance liquid chromatography-mass/mass (HPLC-MS/MS) with chiral columns using acetonitrile/water or methanol/water as mobile phase, and the chromatographic conditions were optimized. Based on the chiral separation, the chiral residue analysis methods for the enantiomers in soil, fruit, and vegetables were set up. Two pairs of the enantiomers were better separated on CHIRALPAK IC chiral column, and baseline simultaneous separations of malathion and malaoxon enantiomers were achieved with acetonitrile/water (40/60, v/v) as mobile phase at a flow rate of 0.5 mL/min. The elution orders were −/+ for both malathion and malaoxon measured by an optical rotation detector. The chiral residue analysis in soil, fruit, and vegetables was validated by linearity, recovery, precision, limit of detection (LOD), and limit of quantification (LOQ). The LODs and LOQs for the enantiomers of malathion were 1 μg/kg and 3–5 μg/kg and 0.08 μg/kg and 0.20–0.25 μg/kg for malaoxon enantiomers. Good linear calibration curves for each enantiomer in the matrices were obtained within the concentration range of 0.02–12 mg/L. The mean recoveries of the enantiomers of malathion and malaoxon ranged from 82.26% to 109.04%, with RSDs of 0.71–8.63%.The results confirmed that this method was capable of simultaneously determining the residue of malathion and malaoxon in food and environmental matrix on an enantiomeric level.