Doses Of Imidacloprid Research Articles

Insecticide resistance and its potential mechanisms in field-collected German cockroaches (Blattodea: Ectobiidae) from Thailand.

We investigated insecticide resistance profiles of field populations of the German cockroach, Blattella germanica (L.), collected from central regions of Thailand. Seven strains (PW, RB, MTH, MTS, TL, AY, and SP) were evaluated with diagnostic doses (DD; 3 × LD95 generated from a susceptible strain) of deltamethrin, fipronil, and imidacloprid using topical assays and compared with a susceptible strain (DMSC). Results showed fipronil (2-27% mortality), deltamethrin (16-58% mortality), and imidacloprid (15-75% mortality) resistance in the field strains. Synergism studies with piperonyl butoxide (PBO) and S,S,S-tributyl phosphorotrithioate (DEF) in combination with the DD of insecticides significantly increased (P < 0.05) mortality of the test insects of the field strains suggesting the involvement of P450 monooxygenase and esterase pathways of detoxification. Gel bait evaluations demonstrated that all field-collected strains were resistant to Maxforce Forte (0.05% fipronil), Maxforce Fusion (2.15% imidacloprid), and Advion Cockroach Gel Bait (0.6% indoxacarb) with mean survival times ranging from 1.87-8.27, 1.77-11.72, and 1.19-3.56 days, respectively. Molecular detection revealed that the Rdl mutation was completely homozygous in all field-collected strains except in the PW strain. Field-collected strains were screened for 3 voltage-gated sodium channel (VGSC) mutations associated with pyrethroid resistance. The L993F mutation was present in 5 strains, but no C764R and E434K mutations were detected.

Comparative toxicity of two neonicotinoid insecticides at environmentally relevant concentrations to telecoprid dung beetles

Dung beetles (Coleoptera: Scarabaeinae) frequently traverse agricultural matrices in search of ephemeral dung resources and spend extended periods of time burrowing in soil. Neonicotinoids are among the most heavily applied and widely detected insecticides used in conventional agriculture with formulated products designed for row crop and livestock pest suppression. Here, we determined the comparative toxicity of two neonicotinoids (imidacloprid and thiamethoxam) on dung beetles, Canthon spp., under two exposure profiles: direct topical application (acute) and sustained contact with treated-soil (chronic). Imidacloprid was significantly more toxic than thiamethoxam under each exposure scenario. Topical application LD50 values (95% CI) for imidacloprid and thiamethoxam were 19.1 (14.5–25.3) and 378.9 (200.3–716.5) ng/beetle, respectively. After the 10-day soil exposure, the measured percent mortality in the 3 and 9 µg/kg nominal imidacloprid treatments was 35 ± 7% and 39 ± 6%, respectively. Observed mortality in the 9 µg/kg imidacloprid treatment was significantly greater than the control (p = 0.04); however, the 3 µg/kg imidacloprid dose response may be biologically relevant (p = 0.07). Thiamethoxam treatments had similar mortality as the controls (p > 0.8). Environmentally relevant concentrations of imidacloprid measured in airborne particulate matter and non-target soils pose a potential risk to coprophagous scarabs.

How to perceive the insecticide? The Neotropical termite Nasutitermes corniger (Termitidae: Nasutitermitinae) triggers alert behavior after exposure to imidacloprid

In eusocial insects, alarm signaling is used to inform nestmates about threats such as predators, competitors, and pathogens. Such behavior is important for the survival of colonies. However, studies evaluating the effect of insecticides on the alarm in termites have not yet been reported. Here, we inspected the effects of insecticide on alarm communication in Nasutitermes corniger. Specifically, we test the following hypotheses: (1) termite groups exposed to insecticide imidacloprid increase the body shaking movements, displaying an alert behavior; and (2) the alert behavior displayed after exposition to insecticide is dose dependent. Bioassays were conducted evaluating the body shaking movements and walking activity of termite groups exposed and non-exposed to insecticide. Thereafter, body shaking movements were evaluated in groups submitted to different doses of insecticide. In general, exposing termite groups to insecticide resulted in significantly higher body shaking movements compared to non-exposed groups. There was a positive effect of imidacloprid doses on the shaking movements. Walking activity, however, decreases in those groups exposed to the insecticide. Our results demonstrate the existence of ‘insecticide alert behavior’ in N. corniger and it appears to be a previously unrecognized communication mechanism in termites that allows for reducing the intoxication risks in the colony.

A sublethal dose of neonicotinoid imidacloprid precisely sensed and detoxified by a C-minus odorant-binding protein 17 highly expressed in the legs of Apis cerana

As a native honeybee species in East Asia, Apis cerana is essential for the stability of local agricultural and plant ecosystems by its' olfactory system for searching nectar and pollen sources. Odorant-binding proteins (OBPs) existing in the insect's olfactory system can recognize environmental semiochemicals. It was known that sublethal doses of neonicotinoid insecticides could still cause a variety of physiological and behavioral abnormalities in bees. However, the molecular mechanism of A. cerana sensing and response for insecticide has not been further investigated. In this study, we found an A. cerana OBP17 gene significantly up-regulated expressed after exposure to sublethal doses of imidacloprid based on the transcriptomics results. The spatiotemporal expression profiles showed that OBP17 was highly expressed in the legs. Competitive fluorescence binding assays showed that OBP17 had the special and high binding affinity to imidacloprid among the 24 candidate semiochemicals, and the KA value of OBP17 binding with imidacloprid reached the maximum (6.94 × 104 L/mol) at low-temperature. Thermodynamic analysis showed that the quenching mechanism changed from dynamic to static binding interaction with the increasing temperature. Meanwhile, the force changed from hydrogen bond and van der Waals force to hydrophobic interaction and electrostatic force, indicating the interaction exhibits variability and flexibility. Molecular docking showed that Phe107 contributed the most energy. RNA interference (RNAi) results showed that OBP17 knockdown significantly enhanced the electrophysiological response of the bees' forelegs to imidacloprid. Our study indicated that OBP17 could precisely touch and sense sublethal doses of neonicotinoid imidacloprid in the natural environment through its high expression in legs, and the upregulation expression of OBP17 exposure to imidacloprid probably implied that it participate in the detoxification processes of A. cerana. Also, our research enriches the theoretical knowledge of the sensing and detoxifying activities of non-target insects' olfactory sensory system to environmental sublethal doses of systemic insecticides.

Anopheles funestus Populations across Africa Are Broadly Susceptible to Neonicotinoids but with Signals of Possible Cross-Resistance from the GSTe2 Gene.

Evaluating the susceptibility of malaria vectors to the new WHO-recommended products is a key step before large-scale deployment. We mapped the susceptibility profile of Anopheles funestus to neonicotinoids across Africa and established the diagnostic doses of acetamiprid and imidacloprid with acetone + MERO as solvent. Indoor resting An. funestus were collected in 2021 in Cameroon, Malawi, Ghana and Uganda. Susceptibility to clothianidin, imidacloprid and acetamiprid was evaluated using CDC bottle assays and offsprings of the field-caught adults. The L119F-GSTe2 marker was genotyped to assess the potential cross-resistance between clothianidin and this DDT/pyrethroid-resistant marker. Mosquitoes were susceptible to the three neonicotinoids diluted in acetone + MERO, whereas low mortality was noticed with ethanol or acetone alone. The doses of 6 µg/mL and 4 µg/mL were established as diagnostic concentrations of imidacloprid and acetamiprid, respectively, with acetone + MERO. Pre-exposure to synergists significantly restored the susceptibility to clothianidin. A positive correlation was observed between L119F-GSTe2 mutation and clothianidin resistance with the homozygote resistant mosquitoes being more able to survive than heterozygote or susceptible. This study revealed that An. funestus populations across Africa are susceptible to neonicotinoids, and as such, this insecticide class could be effectively implemented to control this species using IRS. However, potential cross-resistance conferred by GSTe2 calls for regular resistance monitoring in the field.

The neuroprotective effect of ascorbic acid against imidacloprid-induced neurotoxicity and the role of HO-1 in mice.

Imidacloprid (IMI) is not only a neurotoxic agricultural pesticide but also a possible food contaminant. The aims of this study were to (1) explore the relationship between recurrent IMI administration and neuronal toxicity in mice and (2) evaluate the potential neuroprotective effect of ascorbic acid (AA), a substance with significant free radical scavenger and having property to block the inflammatory pathways. Mice were categorized as naïve controls (administered vehicles for 28 days); the IMI-treatment animal group (administered po 45-mg/kg body weight of IMI per day for 28 days); and the IMI + AA treatment animal group (administered the same IMI dose + 200 mg/kg of AA orally for 28 days). On day 28, memory losses were assessed using the Y-maze and novel target identification behavioral tests. Mice were sacrificed 24 h after the final IMI treatments, as well as hippocampus tissues, were utilized to determine histological assessments, oxidative stress biomarkers, and Heme oxygenase-1 (HO-1) and nuclear factor erythroid 2-related factor 2 (Nrf2) gene expression levels. The findings demonstrated that IMI-treated mice had substantial impairment of spatial and non-spatial memory functions, as well as reduced antioxidant enzyme and acetylcholinesterase activity. The AA neuroprotective action was achieved through the suppression of the HO-1 expression as well as the stimulation of Nrf2 expression in hippocampal tissues. In summary, recurrent IMI exposure causes oxidative stress and neurotoxicity in mice, and the administration of AA significantly reduces the IMI toxicity possibly by the activation of the HO-1/Nrf2 pathway.

The distribution and human health risk assessment of eight neonicotinoid residues in agricultural soils from four provinces, south China

The widespread use of neonicotinoid (neonic) insecticides in China's agricultural sector has led to high residual concentrations in the agroecosystem. Since soil is the primary source of direct pesticide exposure, soil contamination is a significant concern, particularly in regions with extensive agricultural production. This study aims to determine the spatial distribution of neonics in farmlands from four southern provinces that are home to China's crucial commercial grain bases. By combining eight neonics into imidacloprid-equivalent total neonics (IMIRPF) using the relative potency factor method, the ecological risks to humans were also assessed. The results showed that imidacloprid had the highest detection rate (96%–100%), followed by thiamethoxam and clothianidin, which ranged from 44% to 64%. Maximum and average IMIRPF values in soil samples from Zhejiang Province were 277.02 and 46.05 μg kg−1 (dry weight), respectively. Guangdong (maximum = 191.62 μg kg−1, mean = 39.70 μg kg−1) and Jiangxi (maximum = 199.13 μg kg−1, mean = 28.95 μg kg−1) had comparable IMIRPF while Jiangsu had the lowest level of total neonics, with a maximum of 86.07 μg kg−1 and a mean of 19.49 μg kg−1. A significant positive correlation between IMIRPF and total organic carbon in soils was also found. The average daily doses of neonics from soil-borne exposure through food intake, soil ingestion, inhalation, and dermal contact calculated for adults and children in each province were all lower than the reference dose (RfD, 57 μg kg−1 d−1) of imidacloprid. However, the potential health risk to human health cannot be disregarded, given their increasing use and pervasiveness in the environment. Our results help to raise concerns about the safety of the agroecological environment under neonic exposure in the major agricultural provinces of southern China.

Imidacloprid Pesticide Causes Unexpectedly Severe Bioelement Deficiencies and Imbalance in Honey Bees Even at Sublethal Doses.

Pesticides impair honeybee health in many ways. Imidacloprid (IMD) is a pesticide used worldwide. No information exists on how IMD impact the bees' body bioelement balance, which is essential for bee health. We hypothesized that IMD disturbs this balance and fed the bees (in field conditions) with diets containing 0 ppb (control), 5 ppb (sublethal considered field-relevant), and 200 ppb (adverse) doses of IMD. IMD severely reduced the levels of K, Na, Ca, and Mg (electrolytic) and of Fe, Mo, Mn, Co, Cu, Ni, Se, and Zn, while those of Sn, V, and Cr (enzymatic) were increased. Levels of P, S, Ti, Al, Li, and Sr were also decreased, while only the B content (physiologically essential) was increased. The increase in Tl, Pb, and As levels (toxic) was alarming. Generally, IMD, even in sublethal doses, unexpectedly led to severe bioelement malnutrition in 69% of bioelements and to a stoichiometric mismatch in the remaining ones. This points to the IMD-dependent bioelement disturbance as another, yet unaccounted for, essential metabolic element which can interfere with apian health. Consequently, there is a need for developing methods of bioelement supplementation of the honey bee diet for better preventing bee colony decline and protecting apian health status when faced with pesticides.

Residualidad y disipación de imidacloprid en frutos de palto

Imidacloprid is a neonicotinoid insecticide used to control insect pests in avocado (Persea americana); its excessive application could generate residues above the maximum residue limits (MRL) in the fruit, causing a serious health risk to consumers. The objective of this work was to determine the residues and dissipation of imidacloprid in avocado fruit, Hass variety. The treatments were the doses of Imidacloprid (0.5, 1.0 and 1.5 mL.L-1) under the commercial formulation Thunder 350SC and the forms of application (sprayed to foliage and drip at the foot of the plant). There were six treatments in a completely randomized experimental design with three replications and 18 experimental units (plants). Quantification was by HPLC (QuEChERS). The evaluations were carried out on two matrices (avocado fruit peel and pulp) at 1, 3, 7 and 14 days after the application of Imidacloprid. The application of the 0.5 mL.L-1 dose by drip at the foot of the plant resulted in lower residual and a higher percentage of dissipation in both matrices, higher daily dissipation rate in the pulp, with imidacloprid concentrations that did not exceed the MRL (0.7 mg.kg-1). The application of 1.5 mL.L-1 by spraying resulted in higher residual, and in a lower percentage of dissipation in both matrices, with imidacloprid concentrations in the peel exceeding the MRL at 7 and 14 days. In the pulp, none of the treatments exceeded the MRL.

Sub-Lethal Effects of Bifenthrin and Imidacloprid on Megacephala carolina carolina L. (Coleoptera: Carabidae) in Turfgrass.

The tiger beetle, Megacephala carolina carolina L. (Coleoptera: Carabidae), is a common predator in turfgrass and ornamental landscapes in Georgia, USA. Among insecticides used in turfgrass to control foliar and root-feeding insect pests, bifenthrin and imidacloprid are routinely used. It was unclear whether sub-lethal doses of bifenthrin and imidacloprid could cause nontarget effects on larvae and M. carolina carolina adults. Thus, the objective was to determine the sub-lethal effects of bifenthrin and imidacloprid on larvae and M. carolina carolina adults. The results show that M. carolina carolina larvae actively hunt for passing prey by waiting at the hole of the tunnel during the day and nighttime. This larval behavior was affected by sub-lethal doses (up to 25% of full label rate) of bifenthrin but not of imidacloprid. The walking behavior of adult M. carolina carolina was also altered when exposed to sub-lethal doses of bifenthrin as they traveled further distances at greater velocities than the nontreated control. The results imply that turfgrass managers should avoid treating lawns where tiger beetles have actively colonized.

Glassy-Winged Sharpshooters Cease Feeding and Avoid Plants Treated With Sub-Lethal Doses of the Neonicotinoid Insecticide Imidacloprid.

Insecticides are a primary means for suppressing populations of insects that transmit plant pathogens. Application of insecticides for limiting the spread of insect-transmitted plant pathogens is often most effective when applied on an area-wide scale. The glassy-winged sharpshooter is a vector of the bacterial pathogen Xylella fastidiosa, which causes numerous plant diseases including Pierce's disease of grapevine. The glassy-winged sharpshooter has been the subject of an area-wide suppression program in California for nearly two decades. Overreliance on a limited number of active ingredients including the neonicotinoid imidacloprid has resulted in increased levels of resistance to commonly applied products. In California, glassy-winged sharpshooters move between citrus, an important overwintering host, and vineyards. Accordingly, imidacloprid is routinely applied via the irrigation system in vineyards and citrus orchards. For soil applied applications, it may take days to weeks for concentrations in plants to increase to lethal doses. Further, as the dose of imidacloprid required to kill sharpshooters increases due to resistance, so too does the period that sharpshooters are exposed to sub-lethal doses. Response of glassy-winged sharpshooter to cowpea plants treated with sub-lethal doses of imidacloprid was evaluated by conducting no-choice and choice tests. In no-choice feeding assays, glassy-winged sharpshooters caged on plants treated with sub-lethal doses of imidacloprid ceased feeding and produced little excreta. Further, sub-lethal exposure to a range of doses over a 4-d period did not affect viability over a 9-wk post-exposure holding period on untreated plants. In choice-tests, glassy-winged sharpshooters avoided treated plants and were observed predominately on untreated plants. Results suggest that application of imidacloprid to vineyards and citrus orchards may push glassy-winged sharpshooters out of treated habitats rather than kill them.

Detection of Changes in Monoamine Neurotransmitters by the Neonicotinoid Pesticide Imidacloprid Using Mass Spectrometry

Monoamine neurotransmitters (MAs), including dopamine (DA) and serotonin (5-HT), regulate brain functions such as behavior, memory, and learning. Neonicotinoids are pesticides that are being used more frequently. Neonicotinoid exposure has been observed to produce neurological symptoms, such as altered spontaneous movements and anxiety-like behaviors, which are suspected to be caused by altered MA levels. However, current neurotoxicity tests are not sufficiently sensitive enough to make these determinations. In this study, we performed some behavior tests, and derivatization reagents to improve the ionization efficiency, which was applied to liquid chromatography mass spectrometry (LC-MS/MS) to reveal the effect of neonicotinoid administration on MAs in the brain. We orally administered the neonicotinoid imidacloprid (0, 10, and 50 mg/kg body weight) to C57BL/6NCrSlc mice. In the behavior tests, a decrease in activity was observed. The LC-MS/MS quantification of MAs in various brain regions showed a decrease in some MA levels in the olfactory bulb and the striatum. These results showed, for the first time, that even a low dose of imidacloprid could alter MA levels in various parts of the brain.

Sub-lethal doses of imidacloprid alter food selection in the invasive garden ant Lasius neglectus

Despite several restrictions to their use, neonicotinoid insecticides are still widely employed worldwide. Residual sub-lethal amounts of these chemicals can have detrimental effects on the behavior of non-target insects. Toxic effects on economically important species such as bees have been widely documented, but less is known about their toxic action on other social insects, such as ants. In this study, we assessed the effect of different sub-lethal doses of the neonicotinoid imidacloprid on the ability of colonies of the invasive ant Lasius neglectus to select the most profitable resource. We used Y-shaped mazes having an imidacloprid-polluted or an unpolluted sucrose solution on the two branches. Two sucrose (0.1 M, 0.5 M) and two imidacloprid (1 μg/ml, 10 μg/ml) concentrations were used. In parallel, we evaluated the marking activity of foragers who fed on the same solutions. We found that the 0.1 M sugar solution polluted with 1 μg/ml imidacloprid was significantly more frequently selected in binary choices experiments than the unpolluted resource. Moreover, the ingestion of the same combination of sugar and imidacloprid significantly increased the marking rate of foragers. The higher concentration of the pollutant had lower effects, probably because of the hormesis phenomenon. Results suggest that the lower sub-lethal dose of imidacloprid can lead ants to select again the polluted resource. This “active” selection of the pollutant may magnify the negative effects on the colonies. Due to their ecological role, any impairment of ant survival or behavior may have detrimental cascade effects on the whole ecosystem.

Low doses of imidacloprid induce neurotoxic effects in adult marsh frogs: GFAP, NfL, and angiostatin as biomarkers

Imidacloprid is one of the most widely used insecticides in the world. The neurotoxicity of imidacloprid in adult amphibians has not been studied thoroughly. We investigated the expression of glial fibrillary acidic protein (GFAP), neurofilament light chain (NfL) and angiostatin in the amphibian brain to identify valid biomarkers of low dose imidacloprid exposure. For the experiment, 30 individuals of the marsh frog Pelophylax ridibundus were selected. The amphibians were divided into five groups. The duration of the experiment was 7 and 21 days. The exposure concentrations were 10 and 100 µg/L. The results of the study revealed a decrease in the expression of GFAP after 7 days in the exposure groups of 10 and 100 μg/L. An increase in the level of NfL was observed in the group exposed to 10 μg/L after 21 days of the experiment. The angiostatin level was increased after 7 days at 10 µg/L and after 21 days at 100 µg/L. The data obtained indicate that low concentrations of imidacloprid can cause neurotoxic effects in the brain of P. ridibundus. Such effects can have a significant impact on amphibian populations. According to the results of the study of the expression level of GFAP, NfL and angiostatin, it can be stated that imidacloprid has a neurotoxic effect on adult marsh frogs. The studied indicators can be promising biomarkers of environmental pollution by neonicotinoids.

Field evolved insecticide resistance in the cotton mealybug Phenacoccus solenopsis and its direct and indirect impacts on the endoparasitoid Aenasius arizonensis

Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) an invasive mealybug on cotton is primarily controlled by conventional insecticides. An endoparasitoid Aenasius arizonenesis (Girault) (Hymenoptera: Encyrtidae) is a potential biocontrol agent of this pest. We assessed the susceptibility in field populations of P. solenopsis and A. arizonensis to commonly used insecticides: profenofos, imidacloprid and thiodicarb. Reproductive traits of the parasitoid and Environmental Risk Assessment (ERA) parameters viz., Reduction coefficient, Descriptive analysis, Risk Index (RI), Selectivity ratio and Hazard quotient were measured to assess the direct and indirect effects of these insecticides on the parasitoid. Probit analysis revealed heterogeneity in the insecticide resistance development for both the cotton mealybug and its parasitoid. The field populations of P. solenopsis exhibited resistance to profenofos (18.87–59.86 folds) and thiodicarb (20.07 folds) and susceptibility to imidacloprid. Development of resistance to profenofos was observed in field populations of A. arizonensis. Exposure to lethal doses of imidacloprid and profenofos caused a reduction in parasitization (19–23%) and adult emergence (62–69%) of the parasitoid. Profenofos, thiodicarb and imidacloprid were found to be hazardous, non-selective and harmful to the endoparasitoid, A. arizonensis. There is an urgent need for optimizing insecticide applications for sustainable management of this invasive mealybug in cotton.

An insecticide phenotypic resistance diagnostic kit for cotton aphid Aphis gossypii Glover (Hemiptera Aphididae).

Aphis gossypii is a notorious pest worldwide, and evidence of resistance of A. gossypii to various insecticides has been documented. Diagnostic tools for the rapid and accurate assessment of insecticide resistance are urgently needed to implement effective pest control and insecticide resistance management strategies. Using this diagnostic kit based on the glass vial bioassay, detection results can be obtained in 3h and the values of 897.86, 133.57, 12 037.45, 2849.26, 19 457.33 and 215.60 ng/cm2 were finally identified as the actual diagnostic doses of imidacloprid, acetamiprid, thiamethoxam, nitenpyram, dinotefuran and sulfoxaflor, respectively. The regression equation between mortalities under diagnostic doses and actual resistance ratios tested by the leaf-dipping method were conducted in different strains of A. gossypii, and the diagnostic mortality of A. gossypii was negatively correlated with the resistance ratio to imidacloprid (r=-0.986, P=0.002), acetamiprid (r=-0.964, P=0.008), thiamethoxam (r=-0.930, P=0.022), nitenpyram (r=-0.950, P=0.013), dinotefuran (r=-0.976, P=0.004) and sulfoxaflor (r=-0.937, P=0.019). Moreover, four A. gossypii field populations were selected to apply the diagnostic kit in the field. A diagnostic kit based on the glass vial bioassay for the rapid detection of resistance to imidacloprid, acetamiprid, thiamethoxam, nitenpyram, dinotefuran and sulfoxaflor in A. gossypii was developed. The insecticide diagnostic kit for A. gossypii can be a useful screening tool to determine effective insecticides quickly and accurately. © 2022 Society of Chemical Industry.

Evaluation of Imidacloprid 6%+ Lambda cyhalothrin 4% SL Against Sucking Pests of Cotton

Two field experiments were conducted to evaluate the efficacy of imidacloprid 6%+ lambda cyhalothrin 4% SL against sucking insects viz., aphid Aphis gossypii Glover, leafhopper Amrasca biguttula biguttula (Ishida), thrips Thrips tabaci L. and whitefly Bemisia tabaci (Gennadius) on cotton during kharif, 2018-19 and 2019-20 at the Agricultural Research Station, Dharwad farm, UAS, Dharwad, Karnataka. Results showed that the higher dose of imidacloprid 6%+ lambda cyhalothrin 4%SL @ 500 ml ha-1 resulted in 89.02, 88.52, 91.91 and 90.17% reduction of aphids, thrips, leafhoppers and whitefly, respectively in first season and 93.03, 87.15, 97.01 and 89.65% in second season compared to the untreated check. It was on par with its lower dose @ 450 ml ha-1. There was no significant difference in the counts of grubs and adults of coccinellids and number of chrysopids. Thus, imidacloprid 6%+ lambda cyhalothrin 4% SL could be used for the management of sucking pests without any effect on non-target insects.

The effects of sublethal doses of imidacloprid and deltamethrin on honeybee foraging time and the brain transcriptome

AbstractColony collapse disorder (CCD) has occurred in the United States since 2006 and has been reported in many countries with varying levels of severity. Although the cause of CCD is multifactorial, pesticide is a major factor that leads to colony collapse. At sublethal doses, pesticide is known to negatively affect honeybee physiological development and behaviour. Previously, we found the insecticides imidacloprid and deltamethrin significantly reduced honeybee dancing and foraging efficiency. In our experiments, the duration of honeybee imbibing food at the feeder declined and the returning period from the feeder to the hive increased in both insecticide groups compared with the control group. As a follow‐up, we performed a deep RNA‐seq analysis to reveal the gene regulatory mechanisms underlying this altered foraging performance. Genes involved in detoxification were upregulated in both the imidacloprid and the deltamethrin‐treatment groups. Gene members in immune pathways, odorant receptors and major royal jelly protein families were significantly downregulated in the treatment groups compared with the controls. This fluctuating gene expression profile shows that multifaceted aspects of honeybee physiology were affected by the two insecticides, which may lead to inaccurate communication and impaired learning and memory. Our findings reveal candidate molecular mechanisms leading to impaired dance performance in honeybees exposed to insecticides.

Physiological Responses of the Firefly Pyrocoelia analis (Coleoptera: Lampyridae) to an Environmental Residue From Chemical Pesticide Imidacloprid.

Imidacloprid, a neonicotinoid insecticide, is widely applied to control insect pests across a broad spectrum. Though the impact of residues from this chemical pesticide on non-target organisms in the field has been reported, it was not well characterized across a wide range of ecosystems, especially for some species considered as environmental indicators that live in forests. The effects of sublethal dose of imidacloprid on firefly, Pyrocoelia analis, were analyzed physiologically and biochemically in this study to better understand the impact of chemical pesticide application on environmental indicators such as fireflies. After imidacloprid treatment, the midgut tissues of the larva presented an abnormal morphology featured as atrophy of fat body cells, shrinking cells, and the destruction of a midgut structure. The activities of antioxidant enzymes, superoxide dismutase, catalase, and peroxidase were noticeably increased during early exposure to sublethal imidacloprid and then decreased at later stages. The malondialdehyde content significantly increased after 12 h of exposure to imidacloprid compared with the control. Similarly, the enzyme activities of polyphenol oxidase and acetylcholinesterase were increased after the imidacloprid treatment and then decreased at the later stage. In summary, a sublethal dose of imidacloprid caused destructive change in the tissue structure, and this damage was followed by an excessive reactive oxygen species that could not be eliminated by antioxidant enzymes. Our results indicated that the residues of imidacloprid might cause severe toxicity to non-target insects in the environment even far away from the agro-ecosystem where the chemicals were applied.

Imidacloprid Induced Reproductive Toxicity in Female Albino Rats

Imidacloprid a systemic neonicotinoid, mainly used for controlling insects and pests in agriculturalsector. Two doses of imidacloprid (10 and 20 mg/ kg/ day) were selected based on LD50 and given through oral intubation to female rats for 60 days. Disturbed cyclicity with significant (P&lt;0.05) decrease in the number of estrous cycle days and increased diestrous index was observed at high dose. Serial sections of ovary were studied for atretic follicles in imidacloprid treated rats. Number of healthy follicles was significantly (P&lt;0.05) decreased with increased number of atretic follicles at high dose of imidacloprid. The histopathology of ovary also revealed more atretic follicles at high dose of imidacloprid. Decreased body weight and ovary weight in imidacloprid treated rats was dose dependent. Based on the observed effects, it can be concluded that imidacloprid produced more significant effects on female reproduction at high dose (20 mg/ kgbw/ day) as compared to low dose (10 mg/kgbw/day).