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Organophosphate pesticides (OPs) are used extensively for crop protection worldwide due to their high water solubility and relatively low persistence in the environment compared to other pesticides, such as organochlorines. Dimethoate is a broad-spectrum insecticide that belongs to the thio-organophosphate group of OPs. It is applied to cash crops, animal farms, and houses. It has been used in Pakistan since the 1960s, either alone or in a mixture with other OPs or pyrethroids. However, the uncontrolled use of this pesticide has resulted in residual accumulation in water, soil, and tissues of plants via the food chain, causing toxic effects. This review article has compiled and analyzed data reported in the literature between 1998 and 2021 regarding dimethoate residues and their microbial bioremediation. Different microorganisms such as bacteria, fungi, and algae have shown potential for bioremediation. However, an extensive role of bacteria has been observed compared to other microorganisms. Twenty bacterial, three fungal, and one algal genus with potential for the remediation of dimethoate have been assessed. Active bacterial biodegraders belong to four classes (i) alpha-proteobacteria, (ii) gamma-proteobacteria, (iii) beta-proteobacteria, and (iv) actinobacteria and flavobacteria. Microorganisms, especially bacterial species, are a sustainable technology for dimethoate bioremediation from environmental samples. Yet, new microbial species or consortia should be explored.

Evaluating pesticides' impacts on human health, ecological balance, and agricultural production is the main focus of research on pesticides. The present study aims to investigate the hematological parameters of both genders of albino rats after exposure to dimethoate pesticides. There was a total of eight groups of albino rats, there were two control groups, and treatment groups were further divided into six groups. A low dose of: 5ml was given to the T1 group, a medium dose of 10ml was given to the T2 group, and a high dose of 20 ml was given to the T3 group. Each group contained nine rats in them (n=9). The first two groups of albino rats were taken as the control group and placed in normal conditions. The other six groups of albino rats were administered sub-lethal doses of dimethoate pesticide by mixing this pesticide in food by oral gavage for 90 days. The study showed that the number of white blood cells, platelets count, granulocyte count and lymphocyte count in both genders of albino rats after 30-, 60- and 90-days exposure to dimethoate was significantly increased where simultaneously the number of red blood cells, hemoglobin level, mean corpuscle hemoglobin count, and mean corpuscle hemoglobin concentration count was decreased considerably due to exposure of dimethoate pesticide in both genders of albino rats. No changes observed in the control group of male and female albino rats. This study concluded that dimethoate pesticide effects the blood parameter of male and female albino rats. The study's findings highlight the importance of strict regulatory policies and thorough risk assessment techniques in order to reduce the harmful impacts of pesticides on the health of people and the environment.

This study introduces an indigenous bacterial strain, Exiguobacterium sp. (L.O), isolated from sugarcane fields in Sevur, Tamil Nadu, which has adapted to prolonged exposure to dimethoate. The strain demonstrated the capability to utilize 150 ppm of dimethoate as its sole carbon source, achieving a remarkable degradation rate of 95.87% within 5 days in mineral salt media. Gas chromatography–mass spectrometry (GC–MS) analyses identified the presence of intermediate by-products formed during degradation, like methyl diethanol amine and aspartyl glycine ethyl ester. Notably, phosphorothioic O, O, S-acid, an expected end product in the degradation of dimethoate, was also identified, further confirming the strain’s effective metabolic breakdown of the pesticide. Further degradation study and analysis of changes in functional group was performed by FTIR, and a hypothetical degradation pathway was elucidated showing the course of dimethoate metabolism by the strain. Exiguobacterium sp. (L.O) also displayed significant plant growth-promoting traits, including the production of HCN, IAA, and ammonia and the formation of biofilms, which enhance its utility in agricultural applications. The ecotoxicity study revealed the degradation by-products exhibited reduced toxicity compared to the parent compound dimethoate, highlighting the strain’s potential not only for bioremediation but also for supporting sustainable agricultural practices. This research presents a novel application of Exiguobacterium sp. (L.O), integrating the bioremediation of the organophosphate pesticide dimethoate with agricultural enhancement. This approach is critical for addressing the challenges associated with pesticide pollution in agricultural practices. This study is likely the first to demonstrate the application of this strain in the degradation of dimethoate, as suggested by an extensive review of the literature.

The main objective of the present study was to investigate the toxicity of orally administered organophosphorus dimethoate pesticide in Rattus norvegicus on the basis of biochemical alterations in the blood. There was a total of eight groups: two control groups and six treatment groups. Albino rats of the exposed groups were fed simple laboratory chow along with a low dose: five milliliters were given to the T1 group; the medium dose, ten milliliters, was given to the T2 group; and the high dose, twenty milliliters, was given to the T3 group of dimethoate pesticide for thirty, sixty, or ninety days under controlled laboratory conditions. At the end of the experiment, any weight gain, changes in the blood parameters, or biochemical changes were determined. The results revealed increases in the total glucose, aspartate aminotransferase, and alanine aminotransferase levels in the exposed groups of both genders of albino rats. There were decreases in the levels of urea, uric acid and total bilirubin in the exposed groups of both genders of albino rats. These effects did not vary between the sexes. This study provides a foundation for further research on the long-term effects of dimethoate and similar pesticides, promoting the development of safer alternatives.

Disclosing interactions between pesticides and bee infections is of most interest to understand challenges that pollinators are facing and to which extent bee health is compromised. Here, we address the individual and combined effect that three different pesticides (dimethoate, clothianidin and fluvalinate) and an American foulbrood (AFB) infection have on mortality and the cellular immune response of honeybee larvae. We demonstrate for the first time a synergistic interaction when larvae are exposed to sublethal doses of dimethoate or clothianidin in combination with Paenibacillus larvae , the causative agent of AFB. A significantly higher mortality than the expected sum of the effects of each individual stressor was observed in co-exposed larvae, which was in parallel with a drastic reduction of the total and differential hemocyte counts. Our results underline that characterizing the cellular response of larvae to individual and combined stressors allows unmasking previously undetected sublethal effects of pesticides in colony health.

This research provides a comprehensive understanding of the toxicity of omethoate, a widely used organophosphate pesticide, in a non-target test organism, Allium cepa L. In this study, the control group received distilled water, while the treatment groups were exposed to omethoate at concentrations of 2 mg/L, 3.1 mg/L and 5.7 mg/L for 72 h, respectively.At the end of the experimental period, physiological, cytogenetic, biochemical, and meristematic cell damage level analyses were carried out. Rooting ratio (%), root elongation, and weight gain in the omethoate-treated groups were notably reduced compared to the control. The degree of growth inhibition became more pronounced as the concentration of omethoate increased. Omethoate caused cytogenetic damage, considering the increased micronucleus, chromosomal aberrations, DNA damage, and decreased mitotic index levels compared to control group values. Chromosomal aberrations observed after omethoate exposure were ranked from most to least dense, such as sticky chromosome, vagrant chromosome, fragment, bridge, and unequal chromatin distribution. Omethoate treatment promoted a rise in both activities of superoxide dismutase and catalase and malondialdehyde levels, which are indicators of oxidative stress. Among the other biochemical parameters examined, proline level increased, and chlorophyll a and b levels decreased in omethoate-treated groups. The adverse effects on genotoxicity and biochemical parameters increased as the dose of omethoate increased. The disorders induced by omethoate pesticide in root tip meristem cells were epidermis cell damage, flattened nucleus, cortex cell damage, thickened cortex cell wall, and thickened conduction tissue. According to the findings of this study, omethoate is a chemical that causes multifaceted and dose-dependent toxicity in A . cepa .

The goal of this study was to investigate the protective potential of Tribulus terrestris L. extract (TTE) against omethoate induced toxicity in Allium cepa L. For this purpose, six groups of A. cepa bulbs were established. While tap water was applied to the control group, 25 µg/mL TTE, 50 µg/mL TTE, 5.7 mg/L omethoate, 5.7 mg/L omethoate + 25 µg/mL TTE, and 5.7 mg/L omethoate + 50 µg/mL TTE were applied to the experimental groups, respectively. Omethoate exposure decreased germination percentage, root elongation, weight gain, MI and chlorophyll a and chlorophyll b concentrations compared to control. MN, CAs, DNA tail percentage, proline and MDA levels as well as SOD and CAT activities of the omethoate treated group were higher than the control group. The abnormalities in the root meristem cells were epidermis cell damage, flattened nucleus, cortex cell damage, thickening of the cortex cell wall and transmission tissue thickening. TTE applied in mixture with omethoate alleviated all damages caused by omethoate. The protective effect of TTE was stronger at 50 µg/mL TTE than at 25 µg/mL TTE. TTE at a concentration of 50 µg/mL applied as a mixture with omethoate reduced MN frequency by 46% and DNA tail percentage by approximately 64% compared to omethoate alone. In the omethoate-treated group, the higher concentration of TTE decreased MDA content by 47.5%, proline levels by 38.5%, and SOD and CAT activities by 27.9% and 37.5%, respectively. The most dominant phenolic compounds in TTE were rutin, p-coumaric acid and 4_OH benzoic acid. This study offers a novel, multifaceted assessment demonstrating that TTE can mitigate omethoate-induced physiological, cytogenetic, biochemical, and anatomical damage in A. cepa , highlighting its potential as a plant-derived protective agent. In conclusion, our findings reveal that omethoate is toxic for A. cepa , and TTE mitigates this toxicity, a response related to its bioactive components.

In modern agriculture, control of insect pests is achieved by using insecticides that can also have lethal and sublethal effects on beneficial non-target organisms. Here, we investigate acute toxicity and sublethal effects of four insecticides on the males’ sex pheromone response and the female host finding ability of the Drosophila parasitoid Leptopilina heterotoma . The nicotinic acetylcholine receptor antagonists acetamiprid, flupyradifurone and sulfoxaflor, as well as the acetylcholinesterase inhibitor dimethoate were applied topically as acetone solutions. Males treated with all four insecticides no longer preferred the female sex pheromone in a T-olfactometer. Duration of wing fanning, an element of the pheromone-mediated male courtship behavior, was also reduced by all four insecticides. The ability of females to orientate towards host-infested feeding substrate was not affected by acetamiprid in the tested dose range. However, treatment with dimethoate, flupyradifurone and sulfoxaflor resulted in the loss of the females’ preference for host odor. At the lowest doses interfering with olfactory abilities of L. heterotoma in this study (acetamiprid: 0.21 ng, dimethoate: 0.105 ng, flupyradifurone: 2.1 ng and sulfoxaflor: 0.21 ng), ≥ 90% of the wasps survive insecticide treatment. Male pheromone responses and female host finding were also disturbed in those L. heterotoma that had developed in D. melanogaster larvae reared on dimethoate-treated feeding medium at sublethal levels. Hence, doses of this insecticide sufficient to interfere with chemical orientation of L. heterotoma can be taken up by the parasitoid via the food chain.

Nowadays organophosphate-based chemicals are most commonly used insecticides worldwide which are applicable to a wide range of crop plants. In this study, the effect of organophosphate insecticides, dimethoate (DM) and malathion (MT), was investigated on Solanum lycopersicum L. The seeds were germinated under in vivo conditions and after 1 month of germination, they were transferred to separate pots. Insecticides were applied in three different concentrations (X, 2X, and 4X) using a nozzle spray at 7-day intervals for 21 days where X was the recommended dose. After 21 days of treatment, the toxicological responses of plants were confirmed by evaluating the growth patterns, anatomical, photosynthetic pigments, expression of proteins, and antioxidant enzymes catalase (CAT), guaiacol peroxidase (GPX), and ascorbate peroxidase (APX). The study findings demonstrated that both DM and MT treatment resulted in adverse growth effects even at the initial recommended dose (X) of application. However, compared to MT, at 4X concentrations of DM, maximum decrease in plant height (43.43%), leaf length (43.16%), leaf width (41.09%), and total numbers of leaves per plant (50.57%) was observed. Plants subjected to higher doses of DM and MT showed a gradual reduction in chlorophyll a , chlorophyll b , total chlorophyll, and carotenoids (67.25, 50.00, 62.03, and 41.04%, respectively, for DM and 61.75, 55.72, 59.87, and 41.04%, respectively, for MT). In addition, higher doses of these insecticides greatly disturbed micromorphology and protein contents. At high dose (4X) of treatment, the activities of CAT, GPX, and APX were found to increase by 14.01, 3.62, and 2.21 times the control value, respectively, for DM and 5.17, 2.53, and 1.46 times, respectively, for MT. Additionally, increased isoenzymes of CAT, GPX, and APX were demonstrated by nondenaturing PAGE and were also dependent on the concentrations of DM and MT. These results suggest that the isoforms of the antioxidant enzymes newly developed due to DM and MT excess may be used as biochemical markers for other crop plants grown under insecticide stress. This study provides insights into the biochemical mechanism associated with the toxicity caused to plants by the test insecticides. Graphical Abstract

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a major pest of citrus trees worldwide. A wide variety of insecticides are used to manage D. citri populations within citrus groves in Florida. However, in areas shared by citrus growers and beekeepers the use of insecticides may increase the risks of Apis mellifera  L. (Hymenoptera: Apidae) loss and contaminated honey. The objective of this research was to determine the environmental toxicity of insecticides, spanning five different modes of action used to control D. citri , to A. mellifera . The insecticides investigated were imidacloprid, fenpropathrin, dimethoate, spinetoram and diflubenzuron. In laboratory experiments, LD 50 values were determined and ranged from 0.10 to 0.53 ng/μl for imidacloprid, fenpropathrin, dimethoate and spinetoram. LD 50 values for diflubenzuron were >1000 ng/μl. Also, a hazard quotient was determined and ranged from 1130.43 to 10893.27 for imidacloprid, fenpropathrin, dimethoate, and spinetoram. This quotient was <0.447 for diflubenzuron. In field experiments, residual activity of fenpropathrin and dimethoate applied to citrus caused significant mortality of A. mellifera 3 and 7 days after application. Spinetoram and imidacloprid were moderately toxic to A. mellifera at the recommended rates for D. citri . Diflubenzuron was not toxic to A. mellifera in the field as compared with untreated control plots. Phenoloxidase (PO) activity of A. mellifera was higher than in untreated controls when A. mellifera were exposed to 14 days old residues. The results indicate that diflubenzuron may be safe to apply in citrus when A. mellifera are foraging, while most insecticides used for management of D. citri in citrus are likely hazardous under various exposure scenarios.