Insecticides Malathion Research Articles

Active insecticides for Diaphania hyalinata selective for the natural enemy Solenopsis saevissima

ABSTRACTThe objective of this study was to determine the toxicity of the nine synthetic dienamides against the insect pest Diaphania hyalinata (melonworm) and the selectivity of these substances for the predator Solenopsis saevissima (fire ant). Four bioassays were conducted. To begin with, the dienamides that caused high mortality of D. hyalinata have been selected. In the second bioassay the dose-mortality curves of the selected dienamides have been constructed. In the third bioassay, the survival curves for D. hyalinata and the elapsed time to kill 50% of their population have been determined. In the fourth biological test, the selectivity of the substances to the predator S. saevissima has been evaluated. The most active (2E,4E)-N-butylhexa-2,4-dienamide 3d has killed 95% of the melonworm, D. hyalinata, and less than 10% of the natural enemy S. saevissima. The results presented by this compound are superior to the outcome displayed by the commercial insecticide Malathion®. Three of the dienamides prepared in this manuscript have proven to be selective in killing the pest, but not the beneficial insect.

Current Perspectives on Plague Vector Control in Madagascar: Susceptibility Status of Xenopsylla cheopis to 12 Insecticides.

Plague is a rodent disease transmissible to humans by infected flea bites, and Madagascar is one of the countries with the highest plague incidence in the world. This study reports the susceptibility of the main plague vector Xenopsylla cheopis to 12 different insecticides belonging to 4 insecticide families (carbamates, organophosphates, pyrethroids and organochlorines). Eight populations from different geographical regions of Madagascar previously resistant to deltamethrin were tested with a World Health Organization standard bioassay. Insecticide susceptibility varied amongst populations, but all of them were resistant to six insecticides belonging to pyrethroid and carbamate insecticides (alphacypermethrin, lambdacyhalothrin, etofenprox, deltamethrin, bendiocarb and propoxur). Only one insecticide (dieldrin) was an efficient pulicide for all flea populations. Cross resistances were suspected. This study proposes at least three alternative insecticides (malathion, fenitrothion and cyfluthrin) to replace deltamethrin during plague epidemic responses, but the most efficient insecticide may be different for each population studied. We highlight the importance of continuous insecticide susceptibility surveillance in the areas of high plague risk in Madagascar.

Fungal Biodegradation of Organophosphorus Insecticides and their Impact on Soil Microbial Population

Impact of organophosphrus insecticides Malathion Profenofos and Diazinon were assessed on soil microbial populations. The degradation characteristics of these organophosphrus insecticides at different concentrations, incubation periods and temperature by an isolated fungal strains Trichoderma harzianum and Metarhizium anisopliae were investigated. Fungal population was reduced by 56.37, 51.07 and 26.65 % at 10 day of application by profenofos, diazinon and malathion respectively, compared to the control. Fungal degradion of profenofos , diazinon and malathion increased with increasing incubation peroid but at the same time decreased with increasing initial concentrations of insecticides. Using M. anisopliae, almost 85.60, 77.20 and 68.15 % of initial diazinon was decomposed within 20 days at 10, 20 and 40 mg of diazinon , while profenofos was degraded with 54.70, 62.45 and 63.68 at 20 days at 10, 20 and 40 mg. At 20 mg of initial malathion, more than 90% of the initial concentration was degraded by M. anisopliae. After 10 days of incubation, the degradation % of diazinon at 20, 25, 30, 35 and 40°C was examined to be 17.85, 35.38, 43.45, 33.85, and 7.80 %, while degradation % of Profenofos was examined to be 13.60, 30.35, 35.43, 30.10 and 7.56% respectively, similar results of malathion degradation % were obtained to be 44.78, 50.65, 60.58, 57.73 and 10.28% at 20, 25, 30, 35 and 40°C respectively with using M. anisopliae. Degradation % at 35 °C was 1.90, 2.21 and 1.29 time fasters for diazinon, profenofos and malathion resppectively than those at 20 °C with using M. anisopliae. While degradation % at 35 °C was 2.07, 1.72 and 1.83 times fasters for diazinon , profenofos and malathion resppectively than those at 20 °C with using T. harizianum. On the basis of present findings, these fungal strains can be recommended as potentially effective to protect the environment from the organophosphorus insecticides residues.

Pleurotus ostreatus as a Biodegradator for Organophosphorus Insecticide Malathion

Excessive and continuous use of organophosphorus insecticides as well as malathion has led to the contamination of ecosystems in several rejoins of the world. For its degradation in the ecosystems usage of the microbes has been proved to be the effective method for controlling ecosystems pollution. Biodegradation of pesticides by using microbes have more advantages over the conventional methods. In the present investigation therefore attempts have been made to make use of white rot fungus Pleurotus ostreatus for malathion degradation. Malathion rest quantity at 5, 15 and 25 days was 40.5, 22.6 and 11.8 (μg/100 mL) with degradation % 19.0, 54.8 and 76.4 respectively at initial concentration (50 μg/100 mL). Lignin peroxidase, manganese peroxidase, and laccase production was stimulated with the presence of malathion. At 25 μg/100 mL malathion, productivity of lignin peroxidase, manganese peroxidase, and laccase was 0.51, 0.57 and 4.30 U/ml respectively compared with the control (growth medium without malathion). At low concentrations of malathion (25 and 50 μg) P. ostreatus productivity of these enzymes was more, but at high concentration of malathion the productivity was less than control. Addition of lignin compound induced the productivity of ligninolytic enzymes and therefore the biodegradation of malathion was increased. GC/MS analysis revealed the presence of many products as a result of malathion biodegradation including diethyl mercaptosuccinate, methy l,2-(Dimethoxyphosphoryl)-2-(1,2,3- thiadiazol-4-yl) acetate, 3,4-dihydrothienyl (3,4,b)-5-carboxythiophene, Butanedioic acid, 2,2'-Thiodisuccinic acid; 1,1-Dimethyltetradecyl hydrosulfide and Disulfide, di-tert-dodecyl.

Agroinsecticide-induced Clastogenicity in Vicia faba L. Varieties

Cytological karyotyping of Vicia faba L. varieties, viz., IC-526385, IC-424900, IC-391651, and IC-361499, procured from Indian Agricultural Research Institute (IARI), New Delhi, India, revealed disomic (2 n = 12) and asymmetric nature of faba beans. Chromosome structural variations, including total chromatin length (TF %), interestingly noted in V. faba varieties, provided karyological validation of the varietal divergence. An attempt was made here to evaluate clastogenic response of the two commonly used farm insecticides, i.e., malathion and rogor, to select relatively more resistant varieties to these pesticides and to ascertain adequate dose(s) for safe administration of the said insecticides avoiding pollution load in the environment. Root-tips from treated seeds as well as the flower buds from sprayed plants exhibited a wide spectrum of chromosomal abnormalities, such as laggards, micronuclei, disturbed phases, bridges, fragments, and stickiness in a dose-dependent manner. Rogor was more genotoxic than malathion in all cases. Interestingly, however, lower dose (0.1%) of malathion registered a stimulatory effect on the growth of Vicia faba plants. Based on this study, V. faba IC-526385 (most resistant) cultivar and malathion (less clastogenic) insecticide can be recommended for use in farming.

Protective effect of green tea extract on ovary tissue function in rats treated by Malathion insecticide

Protective effect of green tea extract on ovary tissue function in rats treated by Malathion insecticide

How Time of Exposure to the Amphibian Chytrid Fungus AffectsHyla chrysoscelisin the Presence of an Insecticide1

Effects of pathogens on host life-history characteristics can be influenced by changes in the immune system that occur during development as well as by environmental factors that negatively affect immune system function. Amphibians worldwide are experiencing population declines from chytridiomycosis caused by the fungal pathogen Batrachochytrium dendrobatidis. Disease outbreaks can be influenced by timing of exposure to B. dendrobatidis and by abiotic factors, such as pesticides, that could influence susceptibility. To examine the effects of larval pesticide exposure and timing of B. dendrobatidis exposure during development, we exposed Cope’s Gray Treefrogs (Hyla chrysoscelis) to the insecticide malathion throughout larval development and to B. dendrobatidis at 1 or 3 wk posthatching, or after metamorphosis. We reared tadpoles through metamorphosis and then for 28 d in the terrestrial environment to examine treatment effects on larval survival, time to metamorphosis, and mass at metamorphosis, as well as terrestrial survival and growth after metamorphosis. We found that malathion exposure resulted in a decrease in mass at metamorphosis and a decrease in terrestrial growth. Exposure to B. dendrobatidis did not influence larval development, terrestrial growth, or survival, and exposure to malathion appears to not have altered the effects of B. dendrobatidis exposure in a biologically significant way.

Deltamethrin and Malathion insecticides residues in workers honeybees(Apis mellifera) and its relationship to these insecticides concentrations

This study was conducted to detect and identify residues Exterminators (Deltamethrin) of pyrethroid (Pyrethroids group) and (Malathion) of organophosphates group (Organophosphates) in the body of an insect worker honeybees forager , using chemical analysis (Gas Chromatographic Analyses (GC)). Where was The study transactions are: treatment units (the control) is exposed to pesticides, treatment units offered for Deltamethrin pesticide concentrations 1, 2.5, 5, 10 ppm. treatment units offered for pesticide malathion concentrations 1.25,3.125,6.25,12.5 ppm. The results showed The technique of (GC-MS / MS) effective and high selectivity in the detection of residues of these insecticides in the samples tested. There was a positive correlation between the concentration of the insecticide and the value of the average residual pesticide inside the body of the insect. ranged from the lowest level of residues between 0.117 ppm and 0. 350 ppm concentration of 1.00 ppm and 1.250 ppm in each of the insecticides deltamethrin and malathion .The highest level of residues ranged between 3.660 ppm and 5.420 ppm concentration of 10.0 ppm and 12 0.50 ppm in deltamethrin and malathion, respectively. It could be argued that whatever the concentration of the pesticide used in the study, it found residues have deposited inside the bodies of forager honeybees worker . The life of a worker honeybee and longevity depend on the health and safety of members of the beehive, so it is necessary to take into account when the use of pesticides, the seriousness of their application in the continuity of the life of the entire society which in his life depends on this layer of worker bees.

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.

Susceptibility of Anopheles maculipennis to different classes of insecticides in West Azarbaijan Province, Northwestern Iran

ABSTRACT Objective To determine the susceptibility status of Anopheles maculipennis ( An. maculipennis) against the major insecticides used in the health sectors in West Azarbaijan Province, Northwestern Iran. Methods Unfed 3-5 days old adult females of An. maculipennis were collected across the West Azarbaijan Province and were subjected to evaluation of their susceptibility following World Health Organization recommended protocol against six insecticides (permethrin, deltamethrin, propoxur, bendiocarb, malathion and dieldrin) belonging to four different classes. Results In this study, 916 specimens of An. maculipennis were examined against the insecticides which indicated that An. maculipennis was tolerant to permethrin, deltamethrin and dielderin, but displayed resistance against propoxur, bendiocarb and malathion. Conclusions The pattern of resistance in An. maculipennis could be attributed to the agricultural landscapes, agricultural pesticides used and the exposure of the mosquitoes to insecticides. Logical cooperation is needed between the agriculture and health sectors to ensure the judicious use of pesticides in each sector and the management of probable resistance.

The effects of alpha-lipoic acid on breast of female albino rats exposed to malathion: Histopathological and immunohistochemical study

BackgroundThe wide use of the organophosphate insecticide malathion is accompanied by the risk of human exposure and may be involved in the etiology of breast cancers, especially in developing countries. Alpha (α)-lipoic acid, a natural molecule, present in our diet has antioxidant and protective effects in cases such as aging, diabetes mellitus, and vascular and neurodegenerative diseases all in which free radicals are involved. However, there is only scarce data regarding the efficacy and biological activity of α-lipoic acid on malathion-induced breast histopathological changes. AimsTo investigate whether malathion can induce mammary histopathological changes, to immunohistochemically analyze the modulations in proliferation-apoptosis balance associated with these changes, to assess the associated metabolic parameters, antioxidant stress and hormonal profile changes and to elucidate the possible protective effect of α-lipoic acid on malathion induced alterations in rats. Materials and methodsForty Wistar female rats weighing 150–170g were divided into four groups. Group 1: control group were injected intraperitoneally (ip) with saline solution. Group2: animals were injected (ip) with malathion twice a day for five days. Group 3: animals were orally given α-lipoic acid, after three hours of treatment with malathion at the same dose given to group 2. Group 4: animals were treated with α-lipoic acid at the same dose given to group 3. Rats were sacrificed on the 90th day, and breast tissues were analyzed for histopathological and immunohistochemical alterations. Blood samples were collected for biochemical tests. Resultsα-Lipoic acid exhibited a striking reduction of malathion-induced mammary tumor incidence, and reversed intra-tumor histopathological alterations. Alpha lipoic acid suppressed proliferating cell nuclear antigen (PCNA) and p53 expression, induced apoptosis, upregulated proapoptotic protein Bax. ConclusionsOur results provide the experimental evidence that α-lipoic acid exerts chemopreventive effect in the breast hyperplastic and malignant changes by suppressing abnormal cell proliferation and inducing apoptosis with an oncostatic effects during an early-stage breast cancer.

Evaluating Grain Protectant Efficacy of Some Botanicals against Maize Weevil, Sitophilus zeamais M

The production of sorghum is threatened by a wide range of pre-and post harvest pests like stalk borer, sorghum chafer, and Sitophilus spp. Three botanical plants (Tagitus minuta, Datura stramonium and Carissa schimperi) with five concentrations were tested for efficacy to control maize weevil (Sitophilus zeamais Mostch) on stored sorghum seeds under laboratory conditions. The objective was to study the efficacy of some locally available botanicals to control Sitophilus zeamais Mostch and to determine the length of period the grain could be protected by the different treatments. For comparison, two more treatments-standard check Malathion 5% dust plus control (untreated check) were included; and the experiment was replicated three times. The experiment was conducted under room temperature at 25-28C and relative humidity at 70±5% in Kombolcha Plant Health Clinic Laboratory. Powders of each plant component were then mixed thoroughly with 500 gram grains in plastic jars roofed with muslin cloth and tightened with rubber band. Thirty adult weevils were released in each plastic jars. Number of dead weevils was recorded every 21, 42 and 84 days after the treatments were applied. The data was transformed to arcsine scale prior to analysis. Corrected observations were subjected to statistical analysis, factorial ANOVA. All botanicals significantly affected weevil mortality compared to untreated check, but not as effective as synthetic insecticides (Malathion 5% dust). Carissa schimperi (merez) 5% was significantly more effective than the rest botanical rates and the control (P <0.05). In general the result shows that treatment Carissa schimperi (merez) 5% and Tagitus minuta (gimi) 5% can solve poor resources farmers’ problems by integrating them with other cultural measures. However further research are needed to fix the rate graph and the long term effect in large stores of farmers conditions.

A quantitative approach for integrating multiple lines of evidence for the evaluation of environmental health risks.

Decision analysis often considers multiple lines of evidence during the decision making process. Researchers and government agencies have advocated for quantitative weight-of-evidence approaches in which multiple lines of evidence can be considered when estimating risk. Therefore, we utilized Bayesian Markov Chain Monte Carlo to integrate several human-health risk assessment, biomonitoring, and epidemiology studies that have been conducted for two common insecticides (malathion and permethrin) used for adult mosquito management to generate an overall estimate of risk quotient (RQ). The utility of the Bayesian inference for risk management is that the estimated risk represents a probability distribution from which the probability of exceeding a threshold can be estimated. The mean RQs after all studies were incorporated were 0.4386, with a variance of 0.0163 for malathion and 0.3281 with a variance of 0.0083 for permethrin. After taking into account all of the evidence available on the risks of ULV insecticides, the probability that malathion or permethrin would exceed a level of concern was less than 0.0001. Bayesian estimates can substantially improve decisions by allowing decision makers to estimate the probability that a risk will exceed a level of concern by considering seemingly disparate lines of evidence.

A regulatory perspective on the potential carcinogenicity of glyphosate

Abstract Background: On March 20th of 2015, the International Research on Cancer (IARC), affiliated with the World Health Organization (WHO), classified two organophosphate insecticides (malathion and diazinon) and one

Investigation of differences in sensitivity between 3 strains of Daphnia magna (crustacean Cladocera) exposed to malathion (organophosphorous pesticide)

Acute and chronic ecotoxic effects of organophosphorous insecticide malathion (Fyfanon 50 EC 500 g L−1) were investigated on three strains of Daphnia magna. The nominal effective concentrations immobilizing 50% (EC50) of Daphnia after 24 and 48 h were 0.53 and 0.36 μg L−1, 0.70 and 0.44 μg L−1, and 0.75 and 0.46 μg L−1 for the strains 1, 2, and 3 respectively. There was an increase in malathion ecotoxicity with time of exposure as confirmed by chronic studies. In fact, after 21 days of exposure, significant effects on survival (lowest observed effect concentration or LOECs) were recorded at malathion concentrations of 22, 220 and 230 ng L−1 for strains 1, 2 and 3 respectively. Other endpoints were also examined, including reproduction (with different parameters), body length and embryo toxicity. ICs10 and ICs20 were calculated for these different parameters. ICs10 ranged from 4.7 to more than 220 ng L−1 for the three tested strains. The most sensitive parameter was the number of neonates per adult (ICs10 = 4.7 and 10.8 ng L−1 for strains 1 and 2 respectively) or the number of broods (IC10 = 10 ng L−1 for strain 3). Moreover, an increase in embryo development abnormalities was observed at the two highest tested malathion concentrations. Abnormalities comprised undeveloped second antennae, curved or unextended shell spines, and curved post-abdomen spines in live neonates. Results suggest that malathion could act as an endocrine disruptor in D. magna as it interferes with development. It also induces a significant decrease in acetylcholinesterase (AChE) activities for the three strains. Both strains 2 and 3 seemed more sensitive (LOECs = 60 ng L−1) than strain 1 (LOEC = 120 ng L−1). Our results suggest that the AChE activity response can also be used as a biomarker of inter-strain (or inter-clonal) susceptibility (i.e. strain (or clone)-specific response).

Susceptibility to insecticides and resistance mechanisms in Aedes aegypti from the Colombian Caribbean Region

We determined the susceptibility to insecticides and the biochemical and molecular mechanisms involved in resistance in nine populations of Aedes aegypti (L.) of the Colombian Caribbean region. Bioassays were performed on larvae for susceptibility to temephos and on adults to the insecticides malathion, fenitrothion, pirimiphos-methyl, permethrin, deltamethrin, λ-cyhalothrin and cyfluthrin. The resistance ratio (RR) for each insecticide in the populations was determined, using the susceptible Rockefeller strain as a susceptible control. Additionally, we evaluated the response of the populations to the diagnostic dose (DD) of the organochlorine pesticide DDT. The following biochemical mechanisms associated with resistance were studied: α-esterases, β-esterases, mixed-function oxidases (MFO), glutathione s-transferases (GST) and insensitive acetylcholinesterase (iAChE) as well as the presence of kdr I1,016 mutation and its frequency. All populations studied showed susceptibility to the organophosphates evaluated (RR < 5-fold), except for the Puerto Colombia and Soledad populations which showed high resistance (RR 15-fold) and moderate resistance (RR 5-fold) to temephos, respectively, and Sincelejo (Sucre) with moderate resistance to pirimiphos-methyl (RR 5-fold). All populations evaluated with DD of DDT were found to be resistant with 2–28% of mortality. Variability was observed in the resistance to pyrethroids: permethrin (RR 1.2- to 30.8-fold), deltamethrin RR 0.9- to 37.8-fold), λ-cyalothrin (RR 3.4- to 83-fold) and cyfluthrin (RR 0.3- to 33.8-fold). Incipiently α-esterases and MFO levels were found in the Valledupar population; MFO showed the same profile in Cienaga and GST in the Sincelejo population, all other populations showed unaltered profiles of the enzymes evaluated. The kdr I1,016 mutation was found in all populations evaluated with variability in its allelic and genotypic frequencies.

Effects of amphibian chytrid fungus exposure on American toads in the presence of an insecticide.

Abiotic factors such as pesticides may alter the impact of a pathogen on hosts, which could have implications for host-pathogen interactions and may explain variation in disease outbreaks in nature. In the present laboratory experiment, American toad (Anaxyrus americanus) metamorphs were exposed to the amphibian chytrid fungal pathogen Batrachochytrium dendrobatidis (Bd) and environmentally relevant concentrations of the insecticide malathion to determine whether malathion altered the effects of Bd exposure on growth and survival of toad metamorphs. Exposure to Bd significantly decreased survival over the 51 d of the experiment, suggesting that Bd could reduce recruitment into the terrestrial life stage when exposure occurs at metamorphosis. Malathion did not impact survival, but a 12-h exposure at metamorphosis significantly reduced terrestrial growth. Toads that were exposed to both Bd and malathion showed a nonsignificant trend toward the smallest growth compared with other treatments. The present study suggests that Bd may pose a threat to American toads even though population declines have not been observed for this species; in addition, the presence of both the insecticide malathion and Bd could reduce terrestrial growth, which could have implications for lifetime fitness and suggests that environmental factors could play a role in pathogen impacts in nature.

The effects of the amphibian chytrid fungus, insecticide exposure, and temperature on larval anuran development and survival.

Chytridiomycosis, a disease caused by Batrachochytrium dendrobatidis (Bd), has been implicated as a cause of amphibian declines. Susceptibility may be influenced by environmental factors that suppress the immune response. The authors conducted a laboratory study to examine the effect of temperature, insecticide exposure, and Bd exposure during larval anuran development. The authors examined the consequences of exposure to Bd, an insecticide (carbaryl or malathion), and static or fluctuating temperature (15 °C, 20 °C, 25 °C, or 15 °C to 25 °C 72-h flux) on larval development through metamorphosis of the Pacific treefrog (Pseudacris regilla). High and fluctuating temperature had negative effects on survival in the presence of Bd. Insecticides inhibited the effects of Bd; time to tail resorption of Pacific treefrogs decreased when tadpoles were exposed to carbaryl. The present study indicates that abiotic factors may play a role in the host-pathogen interactions in this system.

Low malathion concentrations influence metabolism in Chironomus sancticaroli (Diptera, Chironomidae) in acute and chronic toxicity tests

Low malathion concentrations influence metabolism in Chironomus sancticaroli (Diptera, Chironomidae) in acute and chronic toxicity tests. Organophosphate compounds are used in agro-systems, and in programs to control pathogen vectors. Because they are continuously applied, organophosphates often reach water sources and may have an impact on aquatic life. The effects of acute and chronic exposure to the organophosphate insecticide malathion on the midge Chironomus sancticaroli are evaluated. To that end, three biochemical biomarkers, acetylcholinesterase (AChE), alpha (EST-α) and beta (EST-β) esterase were used. Acute bioassays with five concentrations of malathion, and chronic bioassays with two concentrations of malathion were carried out. In the acute exposure test, AChE, EST-α and EST-β activities declined by 66, 40 and 37%, respectively, at 0.251 µg L-1 and more than 80% at 1.37, 1.96 and 2.51 µg L-1. In chronic exposure tests, AChE and EST-α activities declined by 28 and 15% at 0.251 µg L-1. Results of the present study show that low concentrations of malathion can influence larval metabolism, indicating high toxicity for Chironomus sancticaroli and environmental risk associated with the use of organophosphates.

Insecticide Susceptibility of Aedes aegypti L. (Diptera: Culicidae) in Guerrero, Mexico

With the aim to provide bases to define a regional management strategy of insecticides, the susceptibility of populations of Aedes aegypti from three regions of Guerrero, Mexico, to the insecticides malathion, temefos, chlorpyrifos, pirimiphosmetil, permethrin, lambda-cyhalothrin, propoxur, and spinosin was determinated, using the New Orleans population as a reference. Commercial and technical-grade insecticides were evaluated by residual application in larvae of early fourth instar according to the methodology proposed by the World Health Organization. The mortality was recorded 24 hours after application. Probit analysis was used to determinate the response lines log dose-mortality, LC50 values and the resistant factor for each product. The results indicate that the three populations of A. aegypti were resistant to the insecticide lambda cyhalothrin, and the populations from Acapulco and Costa Chica were moderately resistant to pirimiphos methyl. In contrast, the three field populations were susceptible to malathion, temephos, chlorpyrifos, permethrin, propoxur, and spinosin. However, although some products were found to be effective, it is recommended to use them in rotation combining different modes of action and in conjunction with other alternatives, as removal of breeding sites, to preserve the life of the authorized insecticides. This study provides useful reference information for the development and implementation of strategies for managing and monitoring local insecticide resistance of A. aegypti in Guerrero, Mexico.