Concentrations Of Lambda-cyhalothrin Research Articles

Biochemical targets of chick embryos affected by sub-lethal concentrations of lambda-cyhalothrin and imidacloprid.

The insecticides Lambda-cyhalothrin (LCT) and imidacloprid (IMD) are extensively utilized in Egyptian agriculture. Embryonic chicken is a readily accessible model organism commonly employed in various studies. Eggs of (Gallus Gallus) chicken were immersed in an aqueous solution of two sub-lethal concentrations (0.375 and 0.0375mg/L for LCT; 0.05 and 0.005mg/L for IMD) for 30 sec on the fourth day of incubation of chick embryos. Significant reductions of acetylcholinesterase (AChE) activity of brain 18- and 21-day chicks were observed in the groups treated with LCT and IMD dependent on concentrations. There were significant changes (reduction or enhancement) in serum activity of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) by LCT and IMD at the used concentrations, while non-significant stimulation in the AST/ALT ratio (AAR) was found. In 18th - day embryos, the activities of glutathione S-transferase (GST) and acid phosphatase (ACP) were not significantly changed by LCT but were significantly increased by IMD. Liver alkaline phosphatase (ALP) activity showed no significant change except IMD at 0.05mg/L. However, serum enzyme activity was significantly reduced in all groups. In addition, the tested insecticides caused notable increases in the creatinine and total protein content. The protein profile; proteins separation with sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) showed an increase in four bands that are consistent with the results of the biomarkers level. Findings indicate that even the pesticide's low concentrations are not safe and may lead to severe damage to the embryos and may lead to significant harm or developmental disruption in the embryos.

Assessing ecological responses of exposure to the pyrethroid insecticide lambda-cyhalothrin in sub-tropical freshwater ecosystems

Pyrethroid insecticides are widely detected in aquatic ecosystems due to their extensive use in agriculture and horticulture, which could pose a potential risk to aquatic non-target organisms. While previous ecotoxicological studies have been conducted mainly with standard tests and local species under temperate conditions, scarce information is available on the effects of pyrethroid insecticides on communities and ecosystems under (sub-)tropical conditions. A single application of lambda-cyhalothrin at concentrations of 0, 9, 30, and 100 ng/L was evaluated in outdoor mesocosms under sub-tropical conditions. Lambda-cyhalothrin was found to dissipate rapidly in the water column, with only 11 % and 7 % of the remaining dose measured at 1 and 3 days after application, respectively. Lambda-cyhalothrin concentrations disappeared considerably faster from the water compartment compared to temperate conditions. Consistent decreases in abundance were observed for Lecane lunaris at the medium and higher treatments (NOEC = 9 ng/L) and at the highest treatment (NOEC = 30 ng/L) for Keratella tropica. On the contrary, two taxa belonging to Cladocera (i.e., Ceriodaphnia sp. and Diaphanosoma sp.) showed the most prominent increase in abundance related to the lambda-cyhalothrin treatments. At the community level, a consistent no observed effect concentrations (NOECs) of 9 ng/L could be calculated for the zooplankton community. A marginal significant overall treatment related effect was observed for the macroinvertebrate community. The results of species sensitivity distribution (SSD) analysis based on results of acute toxicity experiments conducted alongside the mesocosm experiment and obtained from the literature indicated that macroinvertebrates from temperate regions may be generally more sensitive than their counterparts in (sub-)tropical regions. Overall, these findings suggest that environmentally relevant concentrations of the pyrethroid insecticide lambda-cyhalothrin may lead to different ecological outcomes in freshwater ecosystems in the (sub-)tropics relative to temperate regions.

Biomarkers at the Individual and Biochemical Level: Effects of Pure and Formulated Lambda-Cyhalothrin in Boana pulchella Tadpoles (Duméril and Bibron, 1841).

We compared the effects of lambda-cyhalothrin as the pure active ingredient and as a formulated product (Zero®), on the larval stage of the autochthonous species Boana pulchella. We evaluated ecotoxicological endpoints, behavioral and developmental alterations, and the biochemical detoxifying, neurotoxic, and oxidative stress responses, covering a wide concentration range from environmental to high application levels. Both pyrethroid preparations displayed similar ecotoxicity (median lethal concentration of ~0.5 mg/L), with the lethal effect of Zero® being more pronounced than that of the active ingredient. Sublethal behavioral alterations in natatory activity were observed at 1000 times lower concentrations, indicating the ecological hazard of tadpole exposure to this pyrethroid at environmentally relevant concentrations. Biochemical endpoints in B. pulchella larvae showed significant responses to lambda-cyhalothrin in the ng/L range; these responses were different for the pure or the formulated product, and they were variable at higher concentrations. Principal components analysis confirmed the prevalence of biochemical responses as early endpoints at the lowest lambda-cyhalothrin concentrations; the Integrated Biomarker Response Index proportionally increased with pyrethroid concentration in a similar way for the pure and the formulated products. We conclude that lambda-cyhalothrin is of concern from an environmental perspective, with particular emphasis on autochthonous anuran development. The battery of biochemical biomarkers included in our study showed a consistent integrated biomarker response, indicating that this is a potent tool for monitoring impacts on amphibians. Environ Toxicol Chem 2024;00:1-11. © 2024 SETAC.

Attenuation Effect of Azolla spp. on Lambda-Cyhalothrin Toxicity to Aquatic Organisms.

Wetlands play a crucial role in providing valuable ecosystem services, including the removal of various pollutants. In agricultural basins, wetlands are exposed to agrochemical loads. This study aims to assess the attenuation effect of the ubiquitous macrophyte Azolla spp. on the toxicity of lambda-cyhalothrin to sensitive aquatic organisms. An indoor mesocosm experiment was conducted to compare the concentration of lambda-cyhalothrin at different time points after pesticide application in vegetated and unvegetated treatments, including a control without pesticide addition. Toxicity tests were performed throughout the experiment on three organisms: a fish (Cnesterodon decemmaculatus), a macroinvertebrate (Hyalella curvispina), and an amphibian (Boana pulchella). The results demonstrated that lambda-cyhalothrin concentration and toxicity in water were significantly lower in the Azolla spp. treatment. Furthermore, the half-life of lambda-cyhalothrin decreased from 1.2days in the unvegetated treatment to 0.4days in the vegetated treatment. The vegetated treatment also resulted in a significantly lower mortality rate for both H. curvispina and C. decemmaculatus. However, no mortality was observed in B. pulchella for any of the treatments. Sublethal effects were observed in this organism, such as lateral bending of the tail and impairment of the ability to swim, which were attenuated in the vegetated treatment. We conclude that Azolla spp. can effectively reduce the concentration and toxicity of lambda-cyhalothrin, suggesting its potential use in farm-scale best management practices to mitigate the effects of pesticide loads from adjacent crops.

Oebalus pugnax (Hemiptera: Pentatomidae) resistance to lambda-cyhalothrin in Texas and efficacy of 2 alternative insecticides in grain sorghum.

Along the Coastal Bend of Texas, the rice stink bug, Oebalus pugnax (F.), is a major pest of grain sorghum and rice that is primarily managed by insecticide applications. Reports of rice stink bug resistance to pyrethroids in Texas first surfaced in 2015 and continued to spread. To determine the status of pyrethroid resistance, rice stink bug populations across Texas and Louisiana were evaluated from 2021 to 2023. Mortality was assessed through glass vial exposures to eight concentrations (0, 0.03, 0.1, 0.3, 1, 3, 10, and 30 μg/vial) of a pyrethroid, lambda-cyhalothrin. The concentration of lambda-cyhalothrin required to kill 50% (LC50) of each population was estimated by probit analysis. Furthermore, the efficacy of insecticides, including lambda-cyhalothrin, dimethoate, and dinotefuran, were evaluated in field experiments conducted in 2021. Our results indicated that 14 of the 21 rice stink bug populations sampled were resistant to lambda-cyhalothrin, with LC50 values ranging from 42 to 1,600 times higher than a susceptible population. In the field trial, lambda-cyhalothrin did not control rice stink bugs. Dinotefuran provided excellent control of nymphs, but dimethoate provided greater control of adult rice stink bugs. To our knowledge, this is the first study to thoroughly evaluate the extent or geographic range of pyrethroid resistance in Texas for rice stink bugs.

Bioaugmentation of a novel bacterial consortium in cotton-planted soil for degradation of lambda-cyhalothrin

Extensive use of lambda-cyhalothrin (LC) for agricultural and domestic pest control leads to the accumulation of its residues in soil and water, which poses a serious threat to the environment. Remediation of LC at the point source is the most effective way to avoid its spread and harmful effects. Therefore, this study was planned to investigate the potential of indigenously isolated bacteria for the remediation of LC in cotton-vegetated soil. Three potent LC-degrading bacteria, Brucella intermedia Halo1, Alcaligenes faecalis CH1S, and Aquamicrobium terrae CH1T, were isolated from pyrethroid-contaminated soil. A consortium CHST comprising these strains was found to exhibit a higher potential for LC degradation as compared to the individual strains. The degradation of LC by CHST was optimized for four varying factors, i.e., pH, inoculum density (ID), carbon source (CS), and initial LC concentrations (PC), by applying the Taguchi design of experiments (DOE). The contribution of each factor to the biodegradation of LC was found in the order: pH > CS > PC > ID. The enhanced degradation of LC (84%) was attained at pH 7.0 in minimum salt medium (MSM) containing 10 mg/L LC and 3% inoculum. The consortium CHST was also augmented in sterilized and un-sterilized soil microcosms at three initial LC concentrations, i.e., 2, 5, and 10 mg/Kg. After 21 days of incubation, complete LC degradation was achieved at 2 mg/Kg initial concentration in sterilized as well as un-sterilized soil, whereas at higher concentrations, the extent of degradation was comparatively less. At 5 mg/Kg, 88 and 96% LC-degradation was observed in sterilized and un-sterilized soil respectively, compared to 79 and 90% degradation at 10 mg/Kg. During biodegradation, the major metabolite of LC, i.e., 3-phenoxybenzoic acid (3-PBA), was formed and further degraded. In the cotton-planted soil spiked with 10 mg/Kg LC, the consortium degraded 91.8% LC as well as improved the agronomic parameters of the cotton plant. In a nutshell, the consortium CHST was found to be a promising candidate for the remediation of LC contaminants at the point source.

Isolation, Characterization and Screening of Potential Lambda-Cyhalothrin-Degrading Bacteria from Cultivated Soil in Moro, Kwara State, Nigeria

The indiscriminate use of Lambda Cyhalothrin (LC), one of the commonly used synthetic pyrethroids (SPs) insecticides in agriculture, has led to the contamination of different environments with potentially serious impacts on the health of humans and animals. This study investigated the presence of LC-degrading bacteria in cultivated soils. Bacteria were isolated from agricultural soil on mineral salt medium (MSM) using an enrichment technique. They were characterized and identified. Their growth in different concentrations (50 mg/L, 75 mg/L, 100 mg/L, and 125 mg/L) of LC was studied, Potential to degrade LC was assessed by the growth of the bacteria in a mineral salts medium containing LC as the sole carbon source over 14 days. Five bacteria able to grow in MSM with LC as the sole source of carbon and on nutrient agar enriched with 100mg/L of LC were isolated. Their growth (turbidity and viable counts of the bacterial cells) increased from the third day till the sixth day, after which it declined till the 14th day. The Lambda Cyhalothrin-degrading bacterial isolates (LCDB) were tentatively identified as Bacillus species, Klebsiella species, Pseudomonas species, and Lysinibacillusspecies. These results indicated that these bacterial isolates are potentially able to degrade LC and can be useful for the remediation of SPs-contaminated agricultural soils.

Midgut Cell Damage and Oxidative Stress in Partamona helleri (Hymenoptera: Apidae) Workers Caused by the Insecticide Lambda-Cyhalothrin.

The stingless bee Partamona helleri plays a role in pollinating both native and cultivated plants in the Neotropics. However, its populations can be reduced by the pyrethroid insecticide lambda-cyhalothrin. This compound may cross the intestinal barrier and circulate through the hemolymph, affecting various non-target bee organs. The aim of the present study was to assess the extent of cellular damage in the midgut and the resulting oxidative stress caused by lambda-cyhalothrin in P. helleri workers. Bees were orally exposed to lambda-cyhalothrin. The lethal concentration at which 50% of the bees died (LC50) was 0.043 mg a.i. L-1. The P. helleri workers were fed this concentration of lambda-cyhalothrin and their midguts were evaluated. The results revealed signs of damage in the midgut epithelium, including pyknotic nuclei, cytoplasm vacuolization, changes in the striated border, and the release of cell fragments, indicating that the midgut was compromised. Furthermore, the ingestion of lambda-cyhalothrin led to an increase in the activity of the detoxification enzyme superoxide dismutase and the levels of the NO2/NO3 markers, indicating oxidative stress. Conversely, the activities of the catalase and glutathione S-transferase enzymes decreased, supporting the occurrence of oxidative stress. In conclusion, the ingestion of lambda-cyhalothrin by P. helleri workers resulted in damage to their midguts and induced oxidative stress.

UGT2B13 and UGT2C1 are involved in lambda-cyhalothrin resistance in Rhopalosiphum padi

Uridine diphosphate-glucuronosyltransferases (UGTs) are major multifunctional detoxification phase II enzymes involved in the metabolic detoxification of xenobiotics. However, their roles in insecticides resistance are still unclear. In this study, we identified two UGTs genes (UGT2B13 and UGT2C1) in Rhopalosiphum padi, a serious insect pest of wheat worldwide. Bioassays results showed that the resistance ratio of R. padi resistance strain (LC-R) to lambda-cyhalothrin (LC) was 2963.8 fold. The roles of UGT2B13 and UGT2C1 in lambda-cyhalothrin resistance were evaluated. Results indicated that the UGTs contents were significantly increased in the LC resistant strain of R. padi. UGT2B13 and UGT2C1 were significantly overexpressed in the LC-R strain. Transcription levels of UGT2B13 and UGT2C1 were relatively higher in the gut of LC-R strain. RNA interference (RNAi) of UGT2B13 or UGT2C1 significantly decreased the UGTs contents of the LC-R aphids and increased mortality of R. padi exposure to the LC50 concentration of LC. This study provides a new view that UGTs are involved in LC resistance of R. padi. The findings will promote further work to detailed the functions of UGTs in the metabolism resistance of insects to insecticides.

Transport model simulation prediction and environmental risk assessment of pyrethroid insecticides in urban artificial lakes caused by rainfall: A case study of Cloud Mountain Park in subhumid climate zone

Pyrethroid insecticides are among urban parks' most widely used and harmful insecticides. The advanced prediction method is the key to studying the pollution and diffusion risk of plant conservation insecticides in parks. A two-dimensional advection-dispersion model was established for the North Lake of Cloud Mountain Park in the subhumid area of Hebei Province. The temporal and spatial distribution of lambda-cyhalothrin pollution required by plant growth in artificial lakes under different rainfall intensities and the time of water renewal after rainfall was simulated and predicted. According to the model efficiency (E: 0.98), mean absolute error (MAE: 0.016–0.064 cm), and root mean square error (RMSE: 0.014–0.041 cm), the prediction results showed that the model fits well. The results showed that the concentration of lambda-cyhalothrin in the artificial lake was positively correlated with the increase in rainfall intensity. Under the three scenarios of moderate rain, heavy rain, and rainstorm, the variation of total pollutants into the lake over time conformed to the first-order dynamic equation (R2＞0.97), and the cumulative rates were 0.013 min−1, 0.019 min−1 and 0.022 min−1, respectively. Under light rain, the accumulation rate of lambda-cyhalothrin showed a double-linear relationship, which was in accordance with the second-order kinetic equation (R2＞0.97). The rapid accumulation rate of early-stage rainfall was 0.0024 min−1, and the slow accumulation rate of late-stage rainfall was 0.0019 min−1. The human health risk assessment predicted by the simulation was lower than the hazard value (Rtgn(a-1): 9.65 E−11–1.12 E−10 a-1). However, the potential risk value to aquatic species was higher (RQ: 0.33–23.05). In addition, the increase in rainfall intensity has no significant effect on the acceleration of water renewal time. The two-dimensional dispersion model of pollutants driven by water dynamics provided relevant examples for evaluating the impact of runoff on pesticide scour in parks and supplied scientific support for improving the management of artificial lakes in urban parks.

Impact of Lamda-Cyhalothrin on the Biochemical Parameters of Clarias gariepinus

Background: Widespread applications of pesticides such as Lambda cyhalothrin to boost crops production have frequently led to contamination of the fresh water ecosystem in Nigeria.
 Materials and Methods: In this study, Clarias gariepinus were exposed to sub-lethal concentrations of Lambda-cyhalothrin pesticide. The 96 h LC50 of lambda cyhalothrin to the fish was estimated at 3.98mgl-1. Mortality of 100% and 10% were observed in fish exposed to 12.00 mg l-1 and 1.25 mg l-1 of Lambda cyhalothrin respectively as compared to no mortality recorded in the control group. Varying degrees of abnormal behaviours like air gulping, hyperactivity, erratic movement, skin discoloration and jerky movements were observed during the 96 hrs exposure period of the fish to Lambda compared to the control. Exposure to sub-lethal concentrations of Lambda cyhalothrin at 0, 0.25, 0.50 and 1.00 mgl-1 and for 15 days at 5 days intervals that is 5, 10 and 15days led to changes in the biochemical parameters.
 Results: In the Biochemical parameters analysed, there was significant (P<0.5) increase in the mean values of Albumin, Aspartate Amino Transfarase (AST), Alanine Amino Transaferase (ALT), Alkaline Phosphate (ALP) and Creatinine compares to the control group. There was no significant difference (p>0.05) between the values of water quality assays in control and treated group.
 Conclusion: The biomarkers measured could be useful tools for monitoring effects of other pesticides on aquatic organisms. However, further studies could be done to investigate their mode of action to strike a balance between protection of aquatic biota and discharges of these pesticides and their metabolites to aquatic environments.

A Study on the Toxicity and Sublethal Concentrations of Three Insecticides on the Population Dynamics of Green Lacewing Chrysoperla carnea Stephens

Alsendi, A., A.A. Kareem, M. Havasi and Gh. Golmohammadi. 2023. A Study on the Toxicity and Sublethal Concentrations of Three Insecticides on the Population Dynamics of Green Lacewing Chrysoperla carnea Stephens. Arab Journal of Plant Protection, 41(1): 28-36. https://doi.org/10.22268/AJPP-41.1.028036 The study was carried out to evaluate toxicity and sublethal effects of lufenuron, novaluron, and lambda-cyhalothrin on natural enemies such as Chrysoperla carnea. All sub-lethal concentrations caused a significant decrease in oviposition period, total fecundity, longevity, and total life span of C. carnea compared to the control. Maximum and minimum mean lifespan of C. carnea individuals were observed in the untreated group and LC30 concentration of novaluron. Total fecundity varied from 153.47 offspring/individual in treatment with LC30 novaluron to 300.12 offspring/individual in the control treatment. The highest value for intrinsic and finite rate of increase (r, λ) was obtained by the concentration of lambda-cyhalothrin. The net reproduction rate (R0) reached its lowest level in novaluron treatment. As a result, the effects of sublethal concentrations of lufenuron, novaluron, and lambda-cyhalothrin on C. carnea were assessed and discussed to design improved integrated management programs. Keywords: Integrated pest management, side effects, aphidophagous predators, natural enemies.

Field and Laboratory Studies on the Toxicity of Lambda-Cyhalothrin for Controlling Desert Locust (Schistocerca Gregaria)

Desert locust has negative impact on world vegetation, severely affected Africa and Asia in 2020-21. The pest persists in both gregarious and solitary forms. In Pakistan, the majority of the nation experienced a desert locust attack in 2020. Seven to ten districts in Khyber Pakhtunkhwa were seriously impacted. The study was carried out to test the efficacy of different concentrations of Lambda-cyhalothrin 2.5 EC against adult and hoppers/nymph in field and laboratory conditions. The applied concentration was 4%,3%, 2%, 1% and 0.5 % for adults in field and lab conditions, while 2%, 1.5%, 1%, 0.5% and 0.25% for nymph’s trials. Under field condition against adults all the applied concentrations were at par with each other except 0.5%, which showed significantly lower mortality rate (60%). A similar trend of toxicity was also recorded for the laboratory trials. More than 85% mortality was recorded in all treatment except 0.5%, which was 65%. Against hopper all concentration showed significant higher mortality (above 80%) except the nymphs sprayed with 0.25% concentration under field conditions. Similar results were also obtained for vitro trials against nymphal stage. It is concluded an average concentration (3%) should be applied for adult to avoid resistance and pest escape. For hoppers/nymph the recommended concentration should be 1%. Further studies should be carried out regarding the resistance to different types of insecticides under field and laboratory conditions.

Biochemical effects of lambdacyhalothrin on activities of some detoxifying enzymes of Anopheles gambiae life cycle stages

Recent decrease in global malaria burden was achieved through vector control interventions with pyrethroid insecticides. This study was carried out to determine the influence of lambdacyhalothrin on the physiology and activities of some detoxifying enzymes and to establish the systemic effects on Anopheles gambiae. The life cycle stages of the vector were exposed to six different concentrations of lambdacyhalothrin, in an insectary. After the toxicity tests, 325 each, of the dead eggs, larvae and pupae, and 175 of the dead adults from the toxicity test, were carefully selected and further used for enzyme study. Fifty (50) individuals were used for experimental study and 25 as control, for each of egg, larvae and pupae; 25 were used for experimental study and 25 as control for the adult. Each sample was homogenized in 10ml 0.1M phosphate buffer of pH 7.4, filtered and the filtrate used for enzymes study. Determination of the enzymes: aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) was done using standard biochemical methods. The results showed that 97% mortality of the life cycle stages was achieved following exposure to six concentrations of lambdacyhalothrin. Some concentrations (1 and 05µg/l) induced stimulatory effect on the enzyme activities while others (15 and 25µg/l) elicited inhibitory effect and some (10µg/l and 20µg/l) had no significant effect (p>0.05) on the enzyme activities. Alkaline phosphatase (ALP) was the most active in all the life cycle stages. Nevertheless, in older stages (pupae and adults), AST and ALT activities were significantly (p<0.05) elevated. This suggests that lambdacyhalothrin is promising in providing effective mosquito control. The results also suggest that the enzymes play a part in detoxification of lambdacyhalothrin and hence could be correlated with the pyrethroid tolerance status of A. gambiae.

Determining Pesticide Residues in Bee produce and their Potential Risk to Consumers in Tanzania

Purpose: The purpose of this study was to examine pesticide contamination in bee products in Singida District Municipality of Tanzania, particularly at Kijiji cha Nyuki. The specific focus of the study was to assess the levels of pesticides residues in bee products harvested from the selected bee farms, identifying the common type of pesticides that contaminate honey and honey products on the quality of selected bee products.
 Material and Methods: A mixed methods approach was adopted for this study and collected data both primary and secondary data was collected using physical observation and survey, interviews and questionnaires, the purposive and random sampling techniques was used in this study to select total of 104 participants who was taken as a sample from universal populations. Qualitative and quantitative data were analysed using IBM Statistical Package for Social Sciences (SPSS) Computer Programme version 25, where statistics aspect was determined from the results obtained from both questionnaires and laboratory experiment to the four (4) honey sample Bee pollen One Kg, propolis 500gm, and Bee wax One Kg.
 Findings: The study found 252 pesticides residues ingredients in beeswax with a mean of 0.03 mg/kg. Lambda-cyhalothrin ingredient had 4.20 mg/kg of the total pesticide’s ingredient found in beeswax against 251 which represent the rest of the pesticides ingredient that were concentrated in the beeswax. In regards with the effect of lambda-cyhalothrin identified in beeswax, bee pollen and honey, the results indicate current concentrations of pesticides in beeswax, bee pollen and honey does not pose risk to human health neither to environment, this is an indication that honey produced in the Kijiji cha Nyuki is safe for consumers as there is very low concentrations of lambda-cyhalothrin in each studies area.
 Unique Contribution to the Theory, Practice and Policy: It was noted most of the pesticides that found in honey was agricultural pesticides therefore Theory of Planned Behaviour was relevancy in explain the relationship of individual to use pesticides to the agricultural. Therefore, study will contribute to the beekeeping programme guidelines for quality control of bee products to provide thoughtful mitigate to the amount of pesticide contamination in bee and honey products, the study could contribute to policy design and implementation to understanding of how the regulations outlining the use of insecticides is being implemented, and the current economic condition of studied farms.
 

TOXIC EFFECT OF LAMBDA CYHALOTHRIN AND PRETILACHLOR ON BIOMASS AND HISTOLOGY OF TESTIS OF Lampito mauritii (KINBERG)

Lambda cyhalothrin and pretilachlor is widely used to control agricultural pest but also affect non target organisms like earthworms. The present laboratory study was conducted to determine the effect of Lambda cyhalothrin and Pretilachlor on biomass and histology of testis of Lampito mauritii. Lower and higher sub-lethal concentrations of Lambda cyhalothrin (T1 and T2) and Pretilachlor (T3 and T4) was mixed with soil substrate. Biomass was observed once in 10 days up to 90 days. 10 non clitellate L.mauritii was introduced into each treatment. Soil substrate without lambda cyhalothrin and pretilachlor served as control. The present study was revealed that lambda cyhalothrin and pretilachlor was highly affected the growth of L. mauritii. For histopathology study, four adult L. mauritii were introduced in to C, T1, T2, T3 and T4. After 5th, 15th and 30th day, testis was dissected out. The results reported that histology of testis was highly damaged on 5th and 15th day of experiment than 30th day.

Association of voltage-gated sodium channel mutations with field-evolved pyrethroid resistant phenotypes in soybean aphid and genetic markers for their detection

The frequent use of insecticides to manage soybean aphids, Aphis glycines (Hemiptera: Aphididae), in the United States has contributed to field-evolved resistance. Pyrethroid-resistant aphids have nonsynonymous mutations in the voltage-gated sodium channel (vgsc). We identified a leucine to phenylalanine mutation at position 1014 (L1014F) and a methionine to isoleucine mutation (M918I) of the A. glycines vgsc, both suspected of conferring knockdown resistance (kdr) to lambda-cyhalothrin. We developed molecular markers to identify these mutations in insecticide-resistant aphids. We determined that A. glycines which survived exposure to a diagnostic concentration of lambda-cyhalothrin and bifenthrin via glass-vial bioassays had these mutations, and showed significant changes in the resistance allele frequency between samples collected before and after field application of lambda-cyhalothrin. Thus, a strong association was revealed between aphids with L1014F and M918I vgsc mutations and survival following exposure to pyrethroids. Specifically, the highest survival was observed for aphids with the kdr (L1014F) and heterozygote super-kdr (L1014F + M918I) genotypes following laboratory bioassays and in-field application of lambda-cyhalothrin. These genetic markers could be used as a diagnostic tool for detecting insecticide-resistant A. glycines and monitoring the geographic distribution of pyrethroid resistance. We discuss how generating these types of data could improve our efforts to mitigate the effects of pyrethroid resistance on crop production.

Toxicity Bioassay and Bioaccumulation Studies of Lambda Cyhalothrin on Various Tissues of Channa striatus (Bloch, 1793)

The fresh water fish Channa striatus, were exposed to various concentrations of lambda cyhalothrin to evaluate the 96 h lethal concentration (LC50 and LC100) and its bioaccumulation levels and rates on various tissues. The results obtained from the current study revealed that the pesticides had ill effects on the overall functioning of the fish and found to be highly toxic to the test organisms. Channa striatus after continuous exposure to pyrethroid pesticide lambda cyhalothrin exhibited changes in morphological and behavioral responses when compared to control. The bioaccumulation and bioconcentration of pyrethroid insecticides and subsequent biomagnification are capable to raise many unpredictable issues at different trophic levels even to humans.

Molecular surveillance of resistance to pyrethroids insecticides in Colombian Aedes aegypti populations

In Colombia, organochloride, organophosphate, carbamate, and pyrethroid insecticides are broadly used to control Aedes aegypti populations. However, Colombian mosquito populations have shown variability in their susceptibility profiles to these insecticides, with some expressing high resistance levels. In this study, we analyzed the susceptibility status of ten Colombian field populations of Ae. aegypti to two pyrethroids; permethrin (type-I pyrethroid) and lambda-cyhalothrin (type-II pyrethroid). In addition, we evaluated if mosquitoes pressured with increasing lambda-cyhalothrin concentrations during some filial generations exhibited altered allelic frequency of these kdr mutations and the activity levels of some metabolic enzymes. Mosquitoes from all field populations showed resistance to lambda-cyhalothrin and permethrin. We found that resistance profiles could only be partially explained by kdr mutations and altered enzymatic activities such as esterases and mixed-function oxidases, indicating that other yet unknown mechanisms could be involved. The molecular and biochemical analyses of the most pyrethroid-resistant mosquito population (Acacías) indicated that kdr mutations and altered metabolic enzyme activity are involved in the resistance phenotype expression. In this context, we propose genetic surveillance of the mosquito populations to monitor the emergence of resistance as an excellent initiative to improve mosquito-borne disease control measures.

First Report of Alfalfa Weevil (Coleoptera: Curculionidae) Resistance to Lambda-Cyhalothrin in Montana

Forage alfalfa (Medicago sativa L. [Fabales: Fabacae]) is a major agronomic crop grown nationally and Montana ranks highly in acres harvested. The alfalfa weevil (Hypera postica Gyllenhal [Coleoptera: Curculionidae]) is the primary defoliating pest that requires insecticide applications to prevent yield loss, particularly pyrethroid active ingredients (a.i.) that are both efficacious and cost-effective. Reports from commercial alfalfa producers in Big Horn County, MT, suggested local populations of alfalfa weevil had developed resistance to the pyrethroid a.i. lambda-cyhalothrin (type II pyrethroid). Chemical control is an important component of integrated pest management (IPM) of alfalfa weevil and the loss of pyrethroid a.i. as an effective tool would result in additional production costs. Two locations in southern Big Horn County and nine locations in four other Montana counties where resistance has not been reported were sampled and assayed for resistance to lambda-cyhalothrin. Populations from three counties were susceptible, the concentration causing 50% mortality (LC50) ranged from 0.02 to 0.10 µg/cm2. In contrast, populations from Big Horn County did not reach 50% mortality at the highest concentration of lambda-cyhalothrin tested (3.30 µg/cm2), indicating high levels of resistance have developed in these populations. A field trial in Big Horn County supported laboratory results of resistance; lambda-cyhalothrin at the highest label rate did not reduce alfalfa weevil populations. Additional bioassays suggest cross-resistance to zeta-cypermethrin (type II pyrethroid), but only partial cross-resistance to permethrin (type I pyrethroid).