Doses Of Thiamethoxam Research Articles

Metabolisation of thiamethoxam (a neonicotinoid pesticide) and interaction with the Chronic bee paralysis virus in honeybees

Pathogens and pesticides are likely to co-occur in honeybee hives, but much remains to be investigated regarding their potential interactions. Here, we first investigated the metabolisation kinetics of thiamethoxam in chronically fed honeybees. We show that thiamethoxam, at a dose of 0.25ng/bee/day, is quickly and effectively metabolised into clothianidin, throughout a 20day exposure period. Using a similar chronic exposure to pesticide, we then studied, in a separate experiment, the impact of thiamethoxam and Chronic bee paralysis virus (CBPV) co-exposure in honeybees. The honeybees were exposed to the virus by contact, mimicking the natural transmission route in the hive. We demonstrate that a high dose of thiamethoxam (5.0ng/bee/day) can cause a synergistic increase in mortality in co-exposed honeybees after 8 to 10days of exposure, with no increase in viral loads. At a lower dose (2.5ng/bee/day), there was no synergistic increase of mortality, but viral loads were significantly higher in naturally dead honeybees, compared with sacrificed honeybees exposed to the same conditions. These results show that the interactions between pathogens and pesticides in honeybees can be complex: increasing pesticide doses may not necessarily be linked to a rise in viral loads, suggesting that honeybee tolerance to the viral infection might change with pesticide exposure.

Effect of thiamethoxam on growth, biomass of rice varieties and its specialized herbivore, Scirpophaga incertulas Walker

Pesticides employed as seed treatment provides protection to seedlings against insect pests and diseases. Seed treatment of five rice varieties with thiamethoxam, an active ingredient of Actara 25 WG, showed positive effects on seed emergence, plant root and shoot biomass and reduction in dead heart damage under both controlled and greenhouse conditions. Under controlled condition thiamethoxam increased emergence in all of the rice varieties tested. The highest dose i.e., 2.0 g L−1of thiamethoxam had the maximum positive effects. The plant shoot and root characters were also influenced positively by the seed treatment. The total root length was superior with measurements of 38.6, 26.5 and 27.4 cm at 2.0 g L−1concentration treatment for the rice varieties Ptb 33, AD09219 and AD07073 respectively. Similarly the root shoot ratio also increased positively at the prominent dosage for the varieties Ptb 33, AD07073 and AD09219 showing ratios of 0.402, 0.415 and 0.420 respectively. However, thiamethoxam seed treatment even at 0.50 g/L concentration showed significant difference over the untreated control in all the rice varieties tested. With respect to biomass (fresh and dry root and shoot weight) all the treatment doses of thiamethoxam was superior over the control in which the dose 2.0 g/L showed prominent fresh root and shoot weight in all the three tested varieties. Thus the thiamethoxam seed treatment except at the minimum dose showed increased shoot weight and root weight compared to untreated control. Considering the effect of thiamethoxam on insect pest, the spray application @ 0.2, 0.4, and 0.6 g/L of thiamethoxam 25WG significantly reduced the dead heart damage symptom caused by yellow stem borer in the all the varieties (TN1, Ptb33 and AD09219) tested compared to control treatment. Thus, the present investigation suggests that the bioactivator thiamethoxam when employed as a seed treatment plays a critical role in rice growth and development.

Ação do insecticida tiametoxame aplicado às sementes na emergência e vigor de plântulas de Vigna unguiculata (L.) Walp

The aim of this study was to evaluate the effects of thiamethoxam on the emergence and vigor of cowpea seedlings. The cowpea seeds, cv. ‘Nova era’, were treated with the active ingredient thiamethoxam at dosages of 0.07; 0.14; 0.21; 0.28 e 0.35 g a.i. L‑1. The experimental design used was a randomized block in factorial 2 × 2 × 6, where the first factor were lots of seasons 2013/2014 and 2014/2015, the second factor the two sowing seasons, summer and winter, and the third factor the doses of thiamethoxam. The parameters evaluated were: Percentage emergency, emergency speed index, shoot length and seedling root, and dry weight of shoot and seedling root. There was interaction between the lots and the sowing for the dry mass variable of shoot and root and between doses and the time of planting to emergence and emergence speed index. The insecticide thiamethoxam stimulates the physiological performance of cowpea seeds, occurring positive effects on growth and assimilation of dry matter by the roots, and better initial performance and uniform establishment of seedlings in the winter.

Larval exposure to thiamethoxam and American foulbrood: effects on mortality and cognition in the honey bee Apis mellifera

Here, we examined the in vitro effects of co-exposure to a pathogen and a common neonicotinoid on honey bee larvae survival and on adult learning behavior following a standard olfactory conditioning procedure based on the proboscis extension response paradigm. We exposed or co-exposed honey bee larvae to American foulbrood and to sub-lethal doses of thiamethoxam (chronic exposure). Our results revealed no additive effects between the two stressors on larval mortality. However, the present work provides the first evidence of impaired learning and memory in adult bees that were fed thiamethoxam (0.6 ng/bee) during the larval stage. We also show no alterations in learning and memory in bees after infection with American foulbrood at the larval stage. The present study contributes to our knowledge of the sub-lethal effects of neonicotinoids on honey bee larvae and adults.

Effect of sub-lethal doses of thiamethoxam (a neonicotinoid) on hemato-biochemical parameters in broiler chicks

This project was designed to observe the hemato-biochemical effects of sub-lethal doses of thiamethoxam (TMX) in broiler chicks. A-day old chicks (n = 90) were procured from the local market and maintained under standard housing conditions and divided into five equal groups (18 birds/group). The experimental trial continued for 45 days. Sub-lethal doses of TMX including 50, 100, 200 and 400 mg/kg B.W. to groups A, B, C and D were administered through crop tube, respectively. Group E served as a control. Blood and serum samples were collected from each group on 10th, 17th, 24th, 31st, 38th and 45th day of the experiment. The data were analyzed through ANOVA by MSTAT-C. All hematological parameters were determined. Serum samples were analyzed for ALT, AST, total proteins and urea. It was concluded from this study that even sub-lethal doses of TMX have toxic effects on hematology and biochemical parameters.

English

Thiamethoxam is a neonicotinoid insecticide, which is believed to induce the expression of enzymes and proteins that activate plant defense mechanisms, thus improving the plant resistance to stress factors. The aim of this study was to evaluate the physiological performance of melon and watermelon seeds treated with thiamethoxam. The seed treatment consisted of five doses of thiamethoxam, 0, 2, 4, 6 and 8 mL per kilogram of seeds. The parameters evaluated were measured by a standard germination test, first count of germination test, laboratory vigor tests (accelerated aging and cold tests), and a field vigor test (seedling emergence). Thiamethoxam treatment resulted in increase in the normal seedling percentage in the standard germination, first count of germination, accelerated aging, cold and final seedling emergence tests. The doses of 4.0 to 5.0 mL of thiamethoxam per kilogram of seeds were most efficient in improving the physiological performance of melon and watermelon seeds. Key words: Thiamethoxam, seedling vigor, Cucumis melo, Citrullus lanatus.

Effects of a neonicotinoid pesticide on thermoregulation of African honey bees (Apis mellifera scutellata)

Thiamethoxam is a widely used neonicotinoid pesticide that, as agonist of the nicotinic acetylcholine receptors, has been shown to elicit a variety of sublethal effects in honey bees. However, information concerning neonicotinoid effects on honey bee thermoregulation is lacking. Thermoregulation is an essential ability for the honey bee that guarantees the success of foraging and many in-hive tasks, especially brood rearing. We tested the effects of acute exposure to thiamethoxam (0.2, 1, 2ng/bee) on the thorax temperatures of foragers exposed to low (22°C) and high (33°C) temperature environments. Thiamethoxam significantly altered honey bee thorax temperature at all doses tested; the effects elicited varied depending on the environmental temperature and pesticide dose to which individuals were exposed. When bees were exposed to the high temperature environment, the high dose of thiamethoxam increased their thorax temperature 1–2h after exposure. When bees were exposed to the low temperature, the higher doses of the neonicotinoid reduced bee thorax temperatures 60–90min after treatment. In both experiments, the neonicotinoid decreased the temperature of bees the day following the exposure. After a cold shock (5min at 4°C), the two higher doses elicited a decrease of the thorax temperature, while the lower dose caused an increase, compared to the control. These alterations in thermoregulation caused by thiamethoxam may affect bee foraging activity and a variety of in-hive tasks, likely leading to negative consequences at the colony level. Our results shed light on sublethal effect of pesticides which our bees have to deal with.

Effects of Nosema ceranae and thiametoxam in Apis mellifera: A comparative study in Africanized and Carniolan honey bees.

Multiple stressors, such as chemicals and pathogens, are likely to be detrimental for the health and lifespan of Apis mellifera, a bee species frequently exposed to both factors in the field and inside hives. The main objective of the present study was to evaluate comparatively the health of Carniolan and Africanized honey bees (AHB) co-exposed to thiamethoxam and Nosema ceranae (N. ceranae) spores. Newly-emerged worker honey bees were exposed solely with different sublethal doses of thiamethoxam (2% and 0.2% of LD50 for AHB), which could be consumed by bees under field conditions. Toxicity tests for the Carniolan bees were performed, and the LD50 of thiamethoxam for Carniolan honey bees was 7.86 ng bee(-1). Immunohistological analyses were also performed to detect cell death in the midgut of thiamethoxam and/or N. ceranae treated bees. Thiamethoxam exposure had no negative impact on Nosema development in experimental conditions, but it clearly inhibited cell death in the midgut of thiamethoxam and Nosema-exposed bees, as demonstrated by immunohistochemical data. Indeed, thiamethoxam exposure only had a minor synergistic toxic effect on midgut tissue when applied as a low dose simultaneously with N. ceranae to AHB and Carniolan honey bees, in comparison with the effect caused by both stressors separately. Our data provides insights into the effects of the neonicotenoid thiamethoxam on the AHB and Carniolan honey bee life span, as well as the effects of simultaneous application of thiamethoxam and N. ceranae spores to honey bees.

The toxicological effects of thiamethoxam on Gammarus kischineffensis (Schellenberg 1937) (Crustacea: Amphipoda)

Neonicotinoids are a new group of insecticides, and little is known about their toxicity to nontarget freshwater organisms an potential effects on freshwater ecosystems. The aim of this study is to establish the acute toxicity and histopathological effects of thiamethoxam-based pesticide on the gill tissue of Gammarus kischineffensis. In this study G. kischineffensis samples were exposed to 2.5, 5, 7.5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90 and 100mg/l of commercial grade thiamethoxam for 96h. The 24, 48, 72 and 96h LC50 values were determined as 75.619, 23.505, 8.048 and 3.751mg/l respectively. In histopathological study the individuals were exposed to 0.004, 0.04 and 0.4mg/l thiamethoxam concentrations for 14 days. The results showed that the most common changes at all doses of thiamethoxam were vacuolization and hemostatic infiltration in the gill tissue of G. kischineffensis.

Isoenzyme Expression in Bean Seed Germination Treated with Thiamethoxam with and without Drought Stress

The thiamethoxam acts as enhancer, allowing maximize the expression of seed vigor. Isozymes are products of gene expression, highly influenced by the environment, because genes that control its expression are manifested in certain stages of development and in specific organs and tissues, or even under the action of certain stimulus. This study evaluated the isoenzyme expression in bean seedlings from seeds treated with thiamethoxam. Bean seeds were used, cultivar Perola and IAPAR Siriri, submitted or not to drought stress. Seeds were treated at doses of thiamethoxam: 0, 1, 2, 3, 4 and 5 mL·kg-1 of seed. Isozymes were extracted from seedlings collected five days after sowing. We evaluated the expression of isoenzymes: Glutamate Oxalacetate transaminase (GOT), acid phosphatase (FAC), peroxidase (PO), Esterase (EST), malate dehydrogenase (MDH) and glutamate dehydrogenase (GTDH). Interpretation of the results was based on visual analysis of electrophoresis gels, considering the presence/absence and the intensity of each electrophoretic band. Bean seeds treated with thiamethoxam with doses up 3 mL·kg-1 of seed are higher germination untreated, even when submitted to drought stress. The expression of isozymes GOT, FAC, PO, EST, MDH and GTDH is not affected significantly in bean seedlings of Perola and IPR Siriri under different doses of thiamethoxam with and without drought stress.

Hybrid Rice Seed Treatment with Pesticides Improves Its Physiological Quality and Performance

Pathogens in the soil or transmitted by seeds can reduce the stand of plants, affecting the yield of the crop. Furthermore, in the case of rice, the low temperature is a limiting factor in culture. The treatment of seeds with insecticides is an alternative to reduce the damage caused by pests incidents during the early stages of plant development and in some cases, may assist in the germination of seeds exposed to low temperatures. In this sense, the objective of this study was to evaluate the influence of seed treatment with insecticides in the physiological quality and yield of hybrid rice seeds, cv. Inov CL. For this, three experiments were conducted with treated seeds in different doses of thiamethoxam + lambda-cyhalothrin and fipronil totaling seven treatments, including the control (no product). In the first experiment, it was determined seed germination to 10°C, 13°C, 16°C, 20°C and 25°C. In the second experiment, it was assessed seed vigor through accelerated aging, cold test and emergency field. The third experiment was carried out into the field to observe the number of panicles m-2 and crop yield. It is concluded that treatment of hybrid rice seeds, cv. Inov CL with thiamethoxam + lambda-cyhalothrin and fipronil increases the germination percentage of seed and early seedling performance. Treatment of hybrid rice seeds, cv. Inov CL with thiamethoxam + lambda-cyhalothrin provides greater germination and early seedling performance compared to treatment with fipronil. Treatment of hybrid rice seeds, cv. Inov CL with thiamethoxam + lambda-cyhalothrin in dosages of 500 mL 100 kg-11 of seeds or 500 mL 45 kg-1 of seeds increases grain yield.

Synergistic action of Azospirillum brasilense combined with thiamethoxam on the physiological quality of maize seedlings

Plant growth promoting substances, either from biological or chemical origin, are widely used in modern agriculture. In this context, this study evaluated the physiological quality of maize seed treated with thiamethoxam and inoculated with Azospirillum brasilense . Initially, we tested bacterial growth on medium with increasing concentrations of thiamethoxam. We also evaluated the physiological quality of seeds through morphometric measurements, emergence speed index and chlorophyll content by SPAD through a 2x3 factorial arrangement with seed inoculation with A. brasilense (100 mL per 25 kg of seed) and three doses of thiamethoxam (0, 80 and 120 ml per 60,000 seeds). Bacterial population showed a linear reduction according to increasing doses of thiamethoxam. The dose of 120 ml thiamethoxam (42 mg active ingredient) caused a decrease in several variables, while, the inoculation proved a positive activity in seedlings physiological quality. Thus, the inoculation combined with 80 ml thiamethoxam (28 mg active ingredient) show synergistic action in early development in maize seedlings. Keywords: Thiamethoxam, inoculant, plant growth promoting bacteria African Journal of Biotechnology , Vol 13(49) 4501-4507

Use of thiamethoxam as bioactivator on cucumber seed physiological quality and seedling performance

This study aimed to evaluate the effect of insecticide thiamethoxam as a bioactivators on cucumber seed physiological quality and seedling performance. The treatments used were: T1 = no product; T2 = 0.2 L of product per 100 kg of seeds; T3 = 0.3 L product per 100 kg of seeds; T4 = 0.4 L of product per 100 kg seeds; T5 = 0.5 L of product per 100 kg of seeds; T6 = 0.6 L of product per 100 kg of seeds. The variables evaluated were: seed germination, first count of germination, seedling root length, accelerated aging, cold test and seedling emergence. The experimental design was completely randomized with three replicates for each treatment and data were analyzed by regression. Doses of thiamethoxam from 0.3 to 0.4 L (per 100 kg of seed) provide positive effects on cucumber seed physiological quality and seedling performance, as was shown in germination and vigor tests results.

Hazard assessment of the neonicotinoid insecticide thiamethoxam residues in tomato: a prelude to risk assessment profile

A minor modification to the QuEChERS (quick, easy, cheap, effective, rugged and safe) method was carried out for the analysis of thiamethoxam in tomato using high performance liquid chromatography equipped with a diode array detector (HPLC-DAD). The method showed a good linearity with a determination coefficient (R2) of 0.999 for the 0.02–5 mg/L concentration range. The method was validated using a blank tomato spiked at 0.05, 0.1 and 0.5 mg/kg, and the average recovery rate was 96%–99%. The limits of detection and quantification were 0.02 and 0.05 mg/kg, respectively. In this study, dissipation and residual levels of thiamethoxam in tomato under open field conditions were investigated. Thiamethoxam residues tend to dissipate following first-order rate kinetics with a half-life of 2.34 days. At harvest time, the remaining residues of thiamethoxam were below the European Union (EU) maximum residue level of 0.2 mg/kg when measured 14 days after the final application. Exposure of thiamethoxam was determined and compared to acceptable daily intake (ADI). The assessment of consumer exposure was based upon the estimated daily intake (EDI) which was compared to ADI and expressed as percentage. Based upon tomato consumption, the EDI of thiamethoxam ranged from 8.82 × 10−6 to 3.38 × 10−4 mg/kg b.w./day, which corresponds to 0.08% and 3.3% of ADI, respectively. Since the dietary exposure never exceeded 4% ADI, the tomato fruit may be considered safe for human consumption after application of the recommended dose of thiamethoxam.

Cytotoxic effects of thiamethoxam in the midgut and malpighian tubules of Africanized Apis mellifera (Hymenoptera: Apidae)

ABSTRACTDue to its expansion, agriculture has become increasingly dependent on the use of pesticides. However, the indiscriminate use of insecticides has had additional effects on the environment. These products have a broad spectrum of action, and therefore the insecticide affects not only the pests but also non‐target insects such as bees, which are important pollinators of agricultural crops and natural environments. Among the most used pesticides, the neonicotinoids are particularly harmful. One of the neonicotinoids of specific concern is thiamethoxam, which is used on a wide variety of crops and is toxic to bees. Thus, this study aimed to analyze the effects of this insecticide in the midgut and Malpighian tubule cells of Africanized Apis mellifera. Newly emerged workers were exposed until 8 days to a diet containing a sublethal dose of thiamethoxam equal to 1/10 of LC50 (0.0428 ng a.i./l L of diet). The bees were dissected and the organs were processed for transmission electron microscopy. The results showed that thiamethoxam is cytotoxic to midgut and Malpighian tubules. In the midgut, the damage was more evident in bees exposed to the insecticide on the first day. On the eighth day, the cells were ultrastructurally intact suggesting a recovery of this organ. The Malpighian tubules showed pronounced alterations on the eighth day of exposure of bees to the insecticide. This study demonstrates that the continuous exposure to a sublethal dose of thiamethoxam can impair organs that are used during the metabolism of the insecticide. Microsc. Res. Tech. 77:274–281, 2014. © 2014 Wiley Periodicals, Inc.

Influence of combined pesticide and parasite exposure on bumblebee colony traits in the laboratory

Summary Pollinating insects provide vital ecosystem services of enormous importance for economies and biodiversity. Yet, there is a concerning global trend of pollinator declines. Parasites and pesticides are among the suspected principle drivers of these declines. However, especially in the case of key wild pollinators, there are insufficient data on the relative impact of these individual environmental stressors and whether they interact to increase detrimental effects. Using a fully crossed factorial design, we investigated how laboratory exposure to neonicotinoid insecticides, thiamethoxam and clothianidin, over a 9‐week period and a prevalent trypanosome gut parasite Crithidia bombi affects various crucial colony traits of the bumblebee Bombus terrestris. We show that chronic dietary exposure from an early stage of colony development to doses of thiamethoxam and clothianidin that could be encountered in the field truncated worker production, reduced worker longevity and decreased overall colony reproductive success. Further, we demonstrate a significant interaction between neonicotinoid exposure and parasite infection on mother queen survival. The fate of the mother queen is intrinsically linked to colony success, and under combined pressure of parasite infection and neonicotinoid exposure, mother queen survival was lowest. This indicates increased detrimental effects of combined exposure on this crucial colony trait. Combined effects may be exacerbated in stressful natural environments where more pronounced parasite virulence is expected. Synthesis and applications. Our findings reiterate that dietary exposure to neonicotinoids can impact on bumblebee colony performance and fitness. The indication of combined negative effects of ecologically relevant pressures suggests additional adverse consequences for long‐term population dynamics under complex field conditions. To help safeguard pollinator health, whole life‐cycle fitness assessments, particularly for non‐Apis bees, stringently incorporating chronic and sublethal side effects of pesticides, as well as interactions with common natural stressors, such as prevalent parasites, should be considered in the corresponding test guidelines.

A toxicokinetic model for thiamethoxam in rats: implications for higher-tier risk assessment

Risk assessment for mammals is currently based on external exposure measurements, but effects of toxicants are better correlated with the systemically available dose than with the external administered dose. So for risk assessment of pesticides, toxicokinetics should be interpreted in the context of potential exposure in the field taking account of the timescale of exposure and individual patterns of feeding. Internal concentration is the net result of absorption, distribution, metabolism and excretion (ADME). We present a case study for thiamethoxam to show how data from ADME study on rats can be used to parameterize a body burden model which predicts body residue levels after exposures to LD50 dose either as a bolus or eaten at different feeding rates. Kinetic parameters were determined in male and female rats after an intravenous and oral administration of 14C labelled by fitting one-compartment models to measured pesticide concentrations in blood for each individual separately. The concentration of thiamethoxam in blood over time correlated closely with concentrations in other tissues and so was considered representative of pesticide concentration in the whole body. Body burden model simulations showed that maximum body weight-normalized doses of thiamethoxam were lower if the same external dose was ingested normally than if it was force fed in a single bolus dose. This indicates lower risk to rats through dietary exposure than would be estimated from the bolus LD50. The importance of key questions that should be answered before using the body burden approach in risk assessment, data requirements and assumptions made in this study are discussed in detail.

Side‐effects of thiamethoxam on the brain andmidgut of the africanized honeybee Apis mellifera (Hymenopptera: Apidae)

The development of agricultural activities coincides with the increased use of pesticides to control pests, which can also be harmful to nontarget insects such as bees. Thus, the goal of this work was assess the toxic effects of thiamethoxam on newly emerged worker bees of Apis mellifera (africanized honeybee-AHB). Initially, we determined that the lethal concentration 50 (LC50 ) of thiamethoxam was 4.28 ng a.i./μL of diet. To determine the lethal time 50 (LT50 ), a survival assay was conducted using diets containing sublethal doses of thiamethoxam equal to 1/10 and 1/100 of the LC50. The group of bees exposed to 1/10 of the LC50 had a 41.2% reduction of lifespan. When AHB samples were analyzed by morphological technique we found the presence of condensed cells in the mushroom bodies and optical lobes in exposed honeybees. Through Xylidine Ponceau technique, we found cells which stained more intensely in groups exposed to thiamethoxam. The digestive and regenerative cells of the midgut from exposed bees also showed morphological and histochemical alterations, like cytoplasm vacuolization, increased apocrine secretion and increased cell elimination. Thus, intoxication with a sublethal doses of thiamethoxam can cause impairment in the brain and midgut of AHB and contribute to the honeybee lifespan reduction.

Ecological relevance in honeybee pesticide risk assessment: developing context-dependent scenarios to manage uncertainty.

OPINION article Front. Physiol., 04 April 2013Sec. Invertebrate Physiology Volume 4 - 2013 | https://doi.org/10.3389/fphys.2013.00062

Effects of combined thiamethoxam and diatomaceous earth on mortality and progeny production of four Pakistani populations of Rhyzopertha dominica (Coleoptera: Bostrichidae) on wheat, rice and maize

Bioassays were conducted to evaluate the effects of combining thiamethoxam at 0.25, 0.5 and 0.75 mg/kg of active ingredient with the diatomaceous earth (DE) formulation, SilicoSec, at the rate of 100 mg/kg against four Pakistan populations of the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae). The tests were carried out with adult beetles on wheat, maize, and rice. Mortality increased with increasing application rates and exposure intervals for each population. Individually, thiamethoxam alone was more effective at the high dose rate than DE alone, but after 14 days of exposure in most cases, there was greater mortality with DE than with the low dose of thiamethoxam. There was greater mortality in wheat than in rice or maize. Populations differed in susceptibility to treatments and production of progeny.