Application Of Neonicotinoid Insecticides Research Articles

Neonicotinoids Impact All Aspects of Bird Life: A Meta-Analysis.

Worldwide, bird populations are declining dramatically. This is especially the case in intensely used agricultural areas where the application of neonicotinoid insecticides is thought to-unintendedly-cause a cascade of negative impacts throughout food webs. Additionally, there could be direct (sub-) lethal impacts of neonicotinoids on birds, but to date there is no comprehensive quantitative assessment to confirm or rule out this possibility. Therefore, we use a meta-analytical approach synthesising 1612 effect sizes from 49 studies and show that neonicotinoids consistently harm bird health, behaviour, reproduction, and survival. Thus, in addition to reduced food availability, the negative direct effects of exposure to neonicotinoids likely contribute to bird population declines globally. Our outcomes are pivotal to consider in future risk assessments and pesticide policy: despite localised bans, the metabolites and residues of neonicotinoids remain present in the environment and in birds and will thus have long-lasting direct effects on both the individual and the population levels.

Neonicotinoids residues in cow milk and health risks to the Chinese general population

The application of neonicotinoid insecticides (NEOs) has increased dramatically in the world since being introduced in 1990s, yet the extent of human exposure and potential health risk is not fully unraveled. In this study, the residues were analyzed of 16 NEOs and their metabolites in 205 commercial cow milk samples circulating in Chinese market. All the milk samples contained at least one quantified NEO, and over 90% of samples contained a cocktail of NEOs. Acetamiprid, N-desmethyl acetamiprid, thiamethoxam, clothianidin and imidaclothiz were the most commonly detected analytes with detection frequencies of 50–88% and medians of 0.011–0.038 ng/mL in milk. Geographical origin was an important factor to influence abundances and levels of NEOs contamination in milk. Chinese local milk bore a significant higher risk from NEOs contamination than the imported milk. In China, the northwest presented the greatest concentrations of the insecticides relative to the north or south. Organic farming, ultra heat treatment and skimming could significantly reduce levels of NEOs contamination in milk. A relative potency factor method was used to evaluate estimated daily intake of NEO insecticides, and found the children had 3.5–5 times higher exposed risk via milk ingestion than the adults. The high frequency of NEOs detection in milk offers us a snapshot of the ubiquity of NEOs in milk, with possible health implications especially for children.

Imidacloprid-mediated alterations on the salivary glands of the Neotropical brown stink bug, Euschistus heros.

The management of the Neotropical brown stinkbug Euschistus heros (Hemiptera: Pentatomidae) in soybean fields has been heavily dependent on the application of neonicotinoid insecticides. Neonicotinoids act primarily by impairing the function of the nicotinic acetylcholine receptors of the nervous system. These compounds also target specific organs (e.g., salivary glands), which may potentiate their insecticidal efficacy. Here, we evaluated whether the exposure to the neonicotinoid imidacloprid would cause cytomorphological changes in the salivary glands of E. heros. First, we determined the lethal concentrations (LCs) of imidacloprid through contact and ingestion. Subsequently, the cytomorphology of the salivary glands were evaluated in insect groups that survived exposure to the LC5 (3.75 mg a.i./L), LC50 (112.5 mg a.i./L), or LC75 (375.0 mg a.i./L, equivalent to the recommended field rate) doses. Imidacloprid induced apoptosis and necrosis in the salivary gland cells according to the insecticide concentration and salivary gland region. All concentrations increased apoptosis and injured cells (e.g., vacuolization, chromatin condensation, swelling of organelles, and plasma membrane rupture) in the principal and accessory salivary glands. Individuals that survived exposure to the highest concentrations (i.e., LC5 and LC50) were more affected, and exhibited several necrotic cells on their main principal salivary glands. Collectively, our results indicate that imidacloprid exerts toxic effects on the non-target organs, such as the salivary glands, which increases the efficacy of this compound in the management of stink bug infestations.

Profiles of urinary neonicotinoids and dialkylphosphates in populations in nine countries

The application of neonicotinoid insecticides (neonics) has increased dramatically as a replacement for organophosphate pesticides (OPs) in recent years. Nevertheless, little is known about human exposure to these pesticides in various countries. In this study, concentrations of 14 neonics and six dialkylphosphate metabolites (DAPs) were determined simultaneously in 566 urine samples collected from nine countries during 2010–2014. The highest sum concentration of 14 neonics was found in urine from Vietnam (median: 12.2 ng/mL) whereas that of six DAPs was from China (18.4 ng/mL). The median concentrations of ∑6 DAPs were twice higher than those of ∑14 neonics across the nine countries, which suggested a greater exposure to OPs than neonics. The overall pattern of urinary pesticide concentrations was similar among the nine countries with dimethylphosphate (DMP) and dimethylthiophosphate (DMTP) accounting for 51–89% of the total pesticide concentrations. Differences in urinary pesticide concentrations between genders (female and male), age groups (≤20, 21–49, and ≥50 years), and regions (cities of Shanghai, Guangzhou and Qiqihar) were examined. Total daily exposure doses to OPs were highest in China (515 μg/day) with 15% of the samples exceeding the U.S. Environmental Protection Agency’s reference dose for chlorpyrifos (18 μg/day). This is the first study to establish baseline levels of OP and neonics exposure in general populations across nine countries.

A Brief Overview on the Application, Potential Exposure Routes, and the Effects of Neonicotinoid Insecticides on the Honey Bee Pest Varroa Mite

The aim of this study was to assess the potential harmful effects of neonicotinoids inside honey bee colonies and especially on the honey bee pest, Varroa destructor. This paper shortly summarized previous studies which investigated the toxicity of neonicotinoids to honey bees. The possible exposure routes of these insecticides to Varroa mites inside and outside bee colonies were studied. And finally, the link between the adverse effects of neonicotinoids and Varroa mite life cycle in the brood cells and the influence of these chemicals on the mites inside bee colonies were investigated. It was concluded that the application of neonicotinoid insecticides on a variety of agricultural crops may result in the exposure of honey bees to these chemicals and as a consequence, Varroa mites (parasites living inside bee colonies) also got exposed to these insecticides indirectly. The present study re-emphasized on ecotoxicological attempts assessing the risk of these insecticides to honey bees as well as on ecological and behavioral aspects of their application inside bee colonies.

The impact of four widely used neonicotinoid insecticides on Tetragonisca angustula (Latreille) (Hymenoptera: Apidae)

Application of neonicotinoid insecticides on crops can reduce the pollination services and population levels of the stingless bee Tetragonisca angustula (Latreille) (Hymenoptera: Apidae) in Neotropical agroecosystems. However, the impact of these insecticides on this bee has not been fully investigated. This study assessed the susceptibility levels of T. angustula to four neonicotinoid insecticides (acetamiprid, imidacloprid, thiacloprid and thiamethoxam), widely used to manage pests on different crops, and their effects on locomotion of the bee. Neonicotinoids with the cyano radical caused lower bee mortality (assessed by mean lethal concentration, LC50), while those compounds with the nitro radical were highly harmful to T. angustula. Locomotion activity was strongly impaired in bees treated with thiacloprid and imidacloprid, while acetamiprid did not affect the locomotion activity, which was similar to the control. Application of thiamethoxam caused hyperactivity, as observed by increases of ∼4.5 and 5.0-fold in mean speed and distance traveled, respectively. These results suggest that applications of neonicotinoid insecticides can negatively affect the pollination activity of T. angustula. These results can also help to develop strategies to conserve these pollinators in agroecosystems.

Evaluation of foliar vis-a-vis soil application of certain insecticides against Phyllocnistis citrella Stainton

The present study is on the evaluation of the efficacy of selected insecticides viz., imidacloprid, acetamiprid, thiamethoxam, along with Bacillus thuringiensis and mineral oil against the citrus leaf miner Phyllocnistis citrella Stainton on rough lemon rootstock. Soil drenching 15 days prior to flush emergence and foliar application coinciding with flush emergence had been compared. The results indicated that soil application of neonicotinoid insecticides remained more effective against leaf miner larvae for longer duration as compared to foliar application. Soil application significantly induced more biomass.

Reproductive parameters of Tetranychus urticae (Acari: Tetranychidae) affected by neonicotinoid insecticides.

Two-spotted spider mite is a major pest of many agricultural and ornamental crops worldwide. Some reports have indicated that application of neonicotinoid insecticides may lead to increased fecundity of this pest. If this is found to be true, the use of these pesticides may cause an outbreak of spider mite populations. Sublethal effects of three neonicotinoids, namely thiacloprid, acetamiprid and thiamethoxam were studied on T. urticae adults at field recommended doses. The experiments were carried out using bean leaf pieces in plastic Petri dishes. The adult mites were treated using two methods: (1) drench application and (2) spraying of leaves with Potter Spray Tower. Our results indicated that all neonicotinoids tested increased T. urticae population. In both treatment methods, acetamiprid treated mites had the highest intrinsic rate of population increase (rm) and finite rate of population increase (λ); and the lowest mean generation time (T) and doubling time among the treatments. If similar results are obtained from greenhouse and field trials, the use of these insecticides requires necessary precautions such as avoiding repeated use of neonicotinoid insecticide for controlling insect pests.

Neonicotinoid Insecticides Alter Induced Defenses and Increase Susceptibility to Spider Mites in Distantly Related Crop Plants

BackgroundChemical suppression of arthropod herbivores is the most common approach to plant protection. Insecticides, however, can cause unintended, adverse consequences for non-target organisms. Previous studies focused on the effects of pesticides on target and non-target pests, predatory arthropods, and concomitant ecological disruptions. Little research, however, has focused on the direct effects of insecticides on plants. Here we demonstrate that applications of neonicotinoid insecticides, one of the most important insecticide classes worldwide, suppress expression of important plant defense genes, alter levels of phytohormones involved in plant defense, and decrease plant resistance to unsusceptible herbivores, spider mites Tetranychus urticae (Acari: Tetranychidae), in multiple, distantly related crop plants.Methodology/Principal FindingsUsing cotton (Gossypium hirsutum), corn (Zea mays) and tomato (Solanum lycopersicum) plants, we show that transcription of phenylalanine amonia lyase, coenzyme A ligase, trypsin protease inhibitor and chitinase are suppressed and concentrations of the phytohormone OPDA and salicylic acid were altered by neonicotinoid insecticides. Consequently, the population growth of spider mites increased from 30% to over 100% on neonicotinoid-treated plants in the greenhouse and by nearly 200% in the field experiment.Conclusions/SignificanceOur findings are important because applications of neonicotinoid insecticides have been associated with outbreaks of spider mites in several unrelated plant species. More importantly, this is the first study to document insecticide-mediated disruption of plant defenses and link it to increased population growth of a non-target herbivore. This study adds to growing evidence that bioactive agrochemicals can have unanticipated ecological effects and suggests that the direct effects of insecticides on plant defenses should be considered when the ecological costs of insecticides are evaluated.

Impact of neonicotinoid insecticides on natural enemies in greenhouse and interiorscape environments

The neonicotinoid insecticides imidacloprid, acetamiprid, dinotefuran, thiamethoxam and clothianidin are commonly used in greenhouses and/or interiorscapes (plant interiorscapes and conservatories) to manage a wide range of plant-feeding insects such as aphids, mealybugs and whiteflies. However, these systemic insecticides may also be harmful to natural enemies, including predators and parasitoids. Predatory insects and mites may be adversely affected by neonicotinoid systemic insecticides when they: (1) feed on pollen, nectar or plant tissue contaminated with the active ingredient; (2) consume the active ingredient of neonicotinoid insecticides while ingesting plant fluids; (3) feed on hosts (prey) that have consumed leaves contaminated with the active ingredient. Parasitoids may be affected negatively by neonicotinoid insecticides because foliar, drench or granular applications may decrease host population levels so that there are not enough hosts to attack and thus sustain parasitoid populations. Furthermore, host quality may be unacceptable for egg laying by parasitoid females. In addition, female parasitoids that host feed may inadvertently ingest a lethal concentration of the active ingredient or a sublethal dose that inhibits foraging or egg laying. There are, however, issues that require further consideration, such as: the types of plant and flower that accumulate active ingredients, and the concentrations in which they are accumulated; the influence of flower age on the level of exposure of natural enemies to the active ingredient; the effect of neonicotinoid metabolites produced within the plant. As such, the application of neonicotinoid insecticides in conjunction with natural enemies in protected culture and interiorscape environments needs further investigation.

Use of Neonicotinoid Insecticides Applied to Soil and Seed for Green Peach Aphid Management on Spinach

The green peach aphid, Myzus persicae Sulzer, a common pest of spinach produced in the Arkansas River Valley of western Arkansas and eastern Oklahoma, is currently managed with foliar applications of neonicotinoid insecticides. Data reported herein indicate that the neonicotinoid insecticdes, imidacloprid and thiamethoxam, can also be applied to spinach seed and into the soil for effective aphid management. In greenhouse studies both imidacloprid (Gaucho) and thiamethoxam (Cruiser) seed treatments were effective against adults and prevented the establishment of juvenile aphids for a period of 12 weeks after planting. Similar results were obtained in field studies. Regardless of rate, each of the neonicotinoid seed treatments significantly reduced the number of aphids when compared to aphid population levels on non-treated spinach. In addition to the seed treatments, in-furrow applications also resulted in significantly lower aphid numbers than on plants in plots not receiving the applications. Tests also demonstrated that imidacloprid (Admire) effectively managed aphid populations after being injected into the soil. Of the seed and soil applications evaluated, the only application method currently available is use of imidacloprid applied into the soil. This method currently offers the spinach producer an alternative management tool for green peach aphid control on spinach. As the labels of imidacloprid and other neonicotinoid insecticides are expanded to include additional use patterns such as seed treatments, effective alternatives to foliar sprays should prove effective for aphid management on spinach. Accepted for publication 10 November 2007. Published 8 February 2008.

Resistance and cross‐resistance to imidacloprid and thiamethoxam in the Colorado potato beetle Leptinotarsa decemlineata

One of the major challenges in managing the Colorado potato beetle, Leptinotarsa decemlineata (Say) is its remarkable ability to develop resistance to virtually every insecticide that has ever been used against it. Resistance is particularly common throughout northeastern USA as far north as Maine. The first instances of resistance to imidacloprid have already been reported from several locations in New York, Delaware and southern Maine. Rotating insecticides with different modes of action may delay insecticide resistance, but successful implementation of this technique depends on a good understanding of resistance and cross-resistance patterns in populations of target pests. LC(50) values were measured for imidacloprid and thiamethoxam in Colorado potato beetle populations from a variety of locations in the USA and Canada using diet incorporation bioassays. The field performance of imidacloprid, thiamethoxam and clothianidin against imidacloprid-resistant beetles on a commercial potato farm in southern Maine was also evaluated. Correlation between LC(50) values for imidacloprid and thiamethoxam was highly significant, even when populations previously exposed to thiamethoxam were excluded from the analysis. There was no statistically detectable difference in the LC(50) values between populations exposed to both insecticides and to imidacloprid alone. Applications of neonicotinoid insecticides at planting delayed build-up of imidacloprid-resistant beetle populations on field plots by 1-2 weeks but failed to provide adequate crop protection. Consistently with bioassay results, there was also substantial cross-resistance among the three tested neonicotinoid insecticides. Results of the present study support the recommendation to avoid rotating imidacloprid with thiamethoxam as a part of a resistance management plan.

Effect of imidacloprid on the reproduction of acaricide‐resistant and susceptible strains of Tetranychus urticae Koch (Acari: Tetranychidae)

Occasional reports linking neonicotinoid insecticide applications to field population outbreaks of the two-spotted spider mite, Tetranychus urticae Koch, have been a topic of concern for integrated pest management (IPM) programmes, particularly in apples. In order to shed light on the factors which may contribute to the occasional field population increase of T. urticae following the application of neonicotinoid insecticides, greenhouse experiments have been set up. Four different T. urticae strains, namely GSS (acaricide-susceptible), WI (organophosphate-selected), USA (a largely uncharacterised strain) and Akita (METI (mitochondrial electron transport inhibitor) acaricide-resistant and cross-resistant to dicofol), were compared for their fecundity without insecticide treatment and for their ovipositional response to foliar and drench applications of the field-relevant dose of imidacloprid (100 mg litre(-1)). Without insecticide treatment, strain GSS laid significantly more eggs (162.50 (+/- 5.43)) than the multiple resistant strain Akita (139.90 (+/- 5.54)) during a 16 day oviposition period. With imidacloprid treatment the highest effect was observed with GSS, with a significantly reduced number of eggs in drench (143.40 (+/- 4.22)) and foliar (144.60 (+/- 5.85)) applications. For strains Akita and USA, no significant differences were observed in oviposition between imidacloprid treatments and controls. The proportion of F1 female offspring decreased significantly with drench application for GSS and WI, while no differences were observed among strains in the survival of F1 immature stages, except for strain USA. The viability of eggs was relatively high (from 82.9 (+/- 4.5)% for USA to 95.2 (+/- 1.2)% for GSS) and not affected by imidacloprid treatments.