Neonicotinoid insecticides negatively affect performance measures of non-target terrestrial arthropods: a meta-analysis

Temporal and spatial trends of imidacloprid-related hazards in France

Neonicotinoids are the top-selling insecticides worldwide. Because of their method of use, mainly to coat seeds, neonicotinoids have been found to widely contaminate the environment. Their high toxicity has been shown to be a major concern in terms of impact on biodiversity, and the use of these insecticides has been associated with population declines of species in different countries. Despite the widespread recognition of the risk of neonicotinoids to biodiversity, their temporal and spatial use remains poorly known in many countries. Yet this information is essential to address the potential impacts of these pesticides on biodiversity and to inform measures to establish protected areas or biodiversity restoration. The present study relied a large publicly available dataset to characterise the temporal and spatial use in France of imidacloprid, the most widely used neonicotinoid worldwide, as well as analysed water contamination surveys between 2005 and 2022 to assess the contamination of the environment. The results show that imidacloprid was the main neonicotinoid used in France over the study period. This use was spatially structured, with higher use in northern and western France, particularly related to cereal and beet crops area. The water contamination survey indicated that imidacloprid has widely contaminated the environment and consequently increased the risk to biodiversity, especially in counties crossed by the Loire, Seine and Vilaine rivers. This risk increased between 2005 and 2018 due to the higher use of imidacloprid and decreased sharply after 2018 due to its ban, although it was reauthorized by derogation for sugar beet in 2021. This study is the first assessment of imidacloprid pressure on biodiversity in France and shows the spatial and temporal correlation between agricultural practices and the freshwater contamination level. These results will help to identify priority areas for mitigation and restoration measures.

Thermal adaptation affects the temperature-dependent toxicity of the insecticide imidacloprid to soil invertebrates

Terrestrial ectotherms are vulnerable to climate change since their biological rates depend on the ambient temperature. As temperature may interact with toxicant exposure, climate change may cause unpredictable responses to toxic stress. A population's thermal adaptation will impact its response to temperature change, but also to interactive effects from temperature and toxicants, but these effects are still not fully understood. Here, we assessed the combined effects of exposure to the insecticide imidacloprid across the temperatures 10-25 °C of two populations of the Collembola Hypogastrura viatica (Tullberg, 1872), by determining their responses in multiple life history traits. The con-specific populations differ considerably in thermal adaptations; one (arctic) is a temperature generalist, while the other (temperate) is a warm-adapted specialist. For both populations, the sub-lethal concentrations of imidacloprid became lethal with increasing temperature. Although the thermal maximum is higher for the warm-adapted population, the reduction in survival was stronger. Growth was reduced by imidacloprid in a temperature-dependent manner, but only at the adult life stage. The decrease in adult body size combined with the absence of an effect on the age at first reproduction suggests a selection on the timing of maturation. Egg production was reduced by imidacloprid in both populations, but the negative effect was only dependent on temperature in the warm-adapted population, with no effect at 10 °C, and decreases of 41 % at 15 °C, and 74 % at 20 °C. For several key traits, the population best adapted to utilize high temperatures was also the most sensitive to toxic stress at higher temperatures. It could be that by allocating more energy to faster growth, development, and reproduction at higher temperatures, the population had less energy for maintenance, making it more sensitive to toxic stress. Our findings demonstrate the need to take into account a population's thermal adaptation when assessing the interactive effects between temperature and other stressors.

Flupyradifurone negatively affects survival, physical condition and mobility in the two-spotted lady beetle (Adalia bipunctata)

Lady beetles play a crucial role in natural ecosystems and agricultural settings. Unfortunately, these insects and more specifically the two-spotted lady beetle (Adalia bipunctata) are currently facing a severe decline in populations due to various stressors, with pesticide exposure being a significant threat. Flupyradifurone is a relatively newly introduced insecticide and as existing research is mainly elucidating its effects on bees there remains a limited understanding of its effects on non-hymenopteran insects, including lady beetles. In this study we investigated the impact of acute orally applied flupyradifurone doses on survival and sublethal parameters such as physical condition and mobility on A. bipunctata. Our findings revealed a significant increase in mortality among individuals subjected to flupyradifurone doses of 19 ng/individual (corresponding to >1.5-2.0 ng active substance (a.s.)/mg body weight (bw). The calculated LD50 of flupyradifurone at 48 h was 2.11 ng a.s./mg bw corresponding to an amount of 26.38 ng/individual. Sublethal consequences were observable immediately after pesticide application. Even at doses as low as 2 ng/individual (corresponding to >0.0-0.5 ng a.s./mg bw), flupyradifurone induced trembling and temporary immobility in treated animals. Furthermore, pesticide intoxication led to hypoactivity, with less distance covered and a decline in straightness of locomotion. In conclusion, our study underscores the harmful effects of flupyradifurone on the two-spotted lady beetle at doses notably lower than those affecting bees. These findings stress the importance of additional research to attain a more holistic understanding of pesticide impacts not only on a broader range of non-target arthropods species, but also on various exposure routes as well as lethal and sublethal effects.

Effects of neonicotinoid residues on non-target soil animals: A case study of meta-analysis

Neonicotinoids (NEOs) are currently the fastest-growing and most widely used insecticide class worldwide. Increasing evidence suggests that long-term NEO residues in the environment have toxic effects on non-target soil animals. However, few studies have conducted surveys on the effects of NEOs on soil animals, and only few have focused on global systematic reviews or meta-analysis to quantify the effects of NEOs on soil animals. Here, we present a meta-analysis of 2940 observations from 113 field and laboratory studies that investigated the effects of NEOs (at concentrations of 0.001-78,600.000 mg/kg) on different soil animals across five indicators (i.e., survival, growth, behavior, reproduction, and biochemical biomarkers). Furthermore, we quantify the effects of NEOs on different species of soil animals. Results show that NEOs inhibit the survival, growth rate, behavior, and reproduction of soil animals, and alter biochemical biomarkers. Both the survival rate and longevity of individuals decreased by 100 % with NEO residues. The mean values of juvenile survival, cocoon number, and egg hatchability were reduced by 97 %, 100 %, and 84 %, respectively. Both individual and cocoon weights were reduced by 82 %, while the growth rate decreased by 88 % with NEO residues. Our meta-analysis confirms that NEOs pose significant negative impacts on soil animals.

Role of Lactic Acid Bacteria in Insecticide Residue Degradation

Lactic acid bacteria are gaining global attention, especially due to their role as a probiotic. They are increasingly being used as a flavoring agent and food preservative. Besides their role in food processing, lactic acid bacteria also have a significant role in degrading insecticide residues in the environment. This review paper highlights the importance of lactic acid bacteria in degrading insecticide residues of various types, such as organochlorines, organophosphorus, synthetic pyrethroids, neonicotinoids, and diamides. The paper discusses the mechanisms employed by lactic acid bacteria to degrade these insecticides, as well as their potential applications in bioremediation. The key enzymes produced by lactic acid bacteria, such as phosphatase and esterase, play a vital role in breaking down insecticide molecules. Furthermore, the paper discusses the challenges and future directions in this field. However, more research is needed to optimize the utilization of lactic acid bacteria in insecticide residue degradation and to develop practical strategies for their implementation in real-world scenarios.

Toxicity evaluation of novel imidacloprid nanoribbons, using somatic mutation and fitness indexes in Drosophila melanogaster

Nanoribbons of imidacloprid, a systemic and chloronicotinyl insecticide, were successfully synthesized by laser-induced fragmentation/exfoliation of imidacloprid powders suspended in water, with widths ranging from 160 to 470 nm, lengths in the micron scale, and thickness of a few atoms layers. The aim of the present study was to examine the effects of acute and chronic exposure to imidacloprid (IMC) bulk and compare its effects with synthesized imidacloprid nanoribbons (IMCNR) on larval and adult viability, developmental time, olfactory capacity, longevity, productivity, and genotoxicity in Drosophila melanogaster. Larvae or adults were exposed at 0.01, 0.02, or 0.03 ppm to IMC or IMCNR. Results demonstrated that IMCNR produced a significant reduction in viability and olfactory ability. IMC did not significantly alter viability and olfactory ability. Similarly, marked differences on longevity were detected between treatment with IMC and IMCNR where the lifespan of males treated with IMC was significantly higher than control while IMCNR produced a reduction. As for productivity, developmental time, and genotoxicity, no marked differences were found between both forms of IMC.

Sublethal acetamiprid affects reproduction, development and disrupts gene expression in Binodoxys communis

At present, understanding of neonicotinoid toxicity in arthropods remains limited. We here evaluated the lethal and sublethal effects of acetamiprid in F0 and F1 generations of Binodoxys communis using a range of sublethal concentrations. The 10% lethal concentration (LC10) and half lethal concentration (LC25) of ACE had negative effects on the B. communis survival rate, adult longevity, parasitism rate, and emergence rate, and significantly prolonged the duration of the developmental cycle. ACE also had intergenerational effects, with some biological indices affected in the F1 generation after pesticide exposure. Transcriptomic analysis demonstrated that differentially expressed genes were enriched in specific pathways including the amino acid metabolism, carbohydrate metabolism, energy metabolism, exogenous metabolism, signal transduction, and glutathione metabolism pathways. These results indicated strong contact toxicity of ACE to B. communis, which may inhibit their biological control capacity. These results improve our understanding of the toxicological mechanisms of parasitic natural enemies in response to insecticide exposure.

The water-exiting behavior and survival of predaceous diving beetles in responses to lambda-cyhalothrin, chlorantraniliprole, and thiamethoxam

Predaceous diving beetles (dytiscids) are important top insect predators in various natural, agricultural, and artificial water bodies. How they respond to human disturbances such as insecticide contamination to their habitats has been understudied. In this study, we investigated the lethal effects of lambda-cyhalothrin, chlorantraniliprole, and thiamethoxam at nominal field concentrations in 3 cm-deep water in a hypothetical paddy field (Ci,3) on adult Dytiscus sinensis Feng (Coleoptera: Dytiscidae). Lambda-cyhalothrin exhibited significant lethal effects on D. sinensis adults with its Ci,3 exceeding the 95 % confidence interval lower limits for 24, 48, 72, and 96 h- LC99. Chlorantraniliprole and thiamethoxam showed no significant lethal effects on D. sinensis adults at their respective Ci,3 at 24, 48, or 72 h. Additionally, we assessed the temporal propensity of D. sinensis adults to exit water contaminated with chlorantraniliprole and thiamethoxam, respectively. There were significantly more individuals that temporally exited the chlorantraniliprole-contaminated water than clean water 30 min after placing a tile island in the test arena. Meanwhile, thiamethoxam-contaminated water did not repel significantly more individuals than clean water when observed at 10, 30, or 60 min. The study highlights the availability and importance of selecting safer insecticides for dytiscid conservation in agricultural and adjacent habitats, considering the potential of these water bodies becoming ecological traps that keep attracting and killing aquatic beneficials. The water-exiting behavior found indicates the capability of some wildlife to effectively avoid further exposure to toxicants.

The interplay between multiple control mechanisms in a host-parasitoid system: a discrete-time stage-structured modelling approach

We propose a discrete-time host-parasitoid model with stage structure in both species. For this model, we establish conditions for the existence and global stability of the extinction and parasitoid-free equilibria as well as conditions for the existence and local stability of an interior equilibrium and system persistence. We study the model numerically to examine how pesticide spraying may interact with natural enemies (parasitoids) to control the pest (host) species. We then extend the model to an impulsive difference system that incorporates both periodic pesticide spraying and augmentation of the natural enemies to suppress the pest population. For this system, we determine when the pest-eradication periodic solution is globally attracting. We also examine how varying the control measures (pesticide concentration, natural enemy augmentation and the frequency of applications) may lead to different pest outbreak or persistence outcomes when eradication does not occur.

Influence of the pesticide flupyradifurone on mobility and physical condition of larval green lacewings

Global pesticide use in agriculture is one reason for the rapid insect decline in recent years. The relatively new pesticide flupyradifurone is neurotoxic to pest insects but considered harmless to bees according to previous risk assessments. With this study, we aim to investigate lethal and sublethal effects of flupyradifurone on larvae of the beneficial arthropod Chrysoperla carnea. We treated the animals orally with field-realistic concentrations of flupyradifurone and examined lethality as well as effects on condition, mobility and locomotion. For the lethal dose 50, we determined a value of > 120-200 ng/mg (corresponding to a mean amount of 219 ng/larva) after 168 h. Abnormal behaviors such as trembling and comatose larvae were observed even at the lowest concentration applied (> 0-20 ng/mg, 59 ng/larva). Mobility analysis showed impaired activity patterns, resulting in acute hypoactivity at all pesticide concentrations and time-delayed hyperactivity in larvae treated with > 40-60 ng/mg (100 ng/larva) and > 80-100 ng/mg (120 ng/larva), respectively. Even locomotion as a fundamental behavioral task was negatively influenced throughout larval development. In conclusion, our results demonstrate that flupyradifurone impacts life and survival of lacewing larvae and may pose-despite its status as bee-friendly-a major threat to insect fauna and environment.

Meta-Analysis of Herbicide Non-Target Effects on Pest Natural Enemies

A critical component of integrated pest management is minimizing disruption of biological control by reducing the use of pesticides with significant non-target effects on natural enemies. Insecticide non-target effects testing for natural enemies has become increasingly common, but research examining the non-target effects of herbicides on natural enemies is scarce, and recommendations regarding herbicide selectivity are non-existent. We used meta-analysis to summarize laboratory bioassays testing non-target effects of herbicides on arthropod natural enemies and identify patterns in taxon susceptibility and active ingredient toxicity. Data were extracted from 78 papers representing 801 total observations. Herbicides increased natural enemy mortality and decreased longevity, reproduction, and predation. Mesostigmatan mites and hemipterans were the most sensitive to herbicides, and spiders, neuropterans, and hymenopterans were the least sensitive. Mortality was higher in juvenile predators versus parasitoids but did not differ between adults; parasitoid juveniles are likely better protected within the host. In terms of acute mortality, metribuzin, glufosinate, and oxyfluorfen were the most harmful herbicides. Only nicosulfuron, rimsulfuron, pendimethalin, phenmedipham, atrazine, and urea did not increase natural enemy mortality. The large effect size of glufosinate is particularly concerning, as it is the most likely replacement herbicide for glyphosate in many crops. Many active ingredients remain under-studied. Our analysis indicates that herbicides have a strong potential to disrupt biological control in cropping systems.

Low concentrations of acetamiprid, deltamethrin, and sulfoxaflor, three commonly used insecticides, adversely affect ant queen survival and egg laying

Ants are key ecosystem service providers and can serve as important biological control agents in pest management. However, the effects of insecticides on common farmland ant species are poorly understood. We tested the effects of three commonly used insecticides on ants (Hymenoptera, Formicidae). The tested insecticides were acetamiprid (neonicotinoid; formulated as Mospilan 20 SP), deltamethrin (pyrethroid; formulated as Sanium Ultra), and sulfoxaflor (sulfilimine; formulated as Gondola). We tested two ant (Hymenoptera: Formicidae) species with different colony founding strategies, Lasius niger (Linnaeus, 1758) and Myrmica rubra (Linnaeus, 1758). We sprayed their queens with insecticides at concentrations recommended for use in foliar applications in agriculture, i.e., at 1.25 g L-1 (acetamiprid), 0.6 g L-1 (sulfoxaflor), and 0.875 g L-1 (deltamethrin). Further, we diluted the compounds in distilled water and tested them at 10%, 1%, and 0.1% of the field-recommended concentrations, and used distilled water as a control. We monitored the survival of the queens and the number of eggs laid. All three tested insecticides caused severe lethal and sublethal concentration-dependent effects. Even at concentrations three orders of magnitudes lower than recommended for field applications, significantly lower numbers of eggs were found in the queens' nests. The extent of the sublethal effects of acetamiprid and sulfoxaflor was concentration-dependent and differed between the two ant species. Besides bees and bumblebees, ants represent an important group of hymenopterans that are severely affected even by low concentrations of the tested compounds and therefore should be included in risk assessment schemes.

Addressing chemical pollution in biodiversity research

Climate change, biodiversity loss, and chemical pollution are planetary-scale emergencies requiring urgent mitigation actions. As these "triple crises" are deeply interlinked, they need to be tackled in an integrative manner. However, while climate change and biodiversity are often studied together, chemical pollution as a global change factor contributing to worldwide biodiversity loss has received much less attention in biodiversity research so far. Here, we review evidence showing that the multifaceted effects of anthropogenic chemicals in the environment are posing a growing threat to biodiversity and ecosystems. Therefore, failure to account for pollution effects may significantly undermine the success of biodiversity protection efforts. We argue that progress in understanding and counteracting the negative impact of chemical pollution on biodiversity requires collective efforts of scientists from different disciplines, including but not limited to ecology, ecotoxicology, and environmental chemistry. Importantly, recent developments in these fields have now enabled comprehensive studies that could efficiently address the manifold interactions between chemicals and ecosystems. Based on their experience with intricate studies of biodiversity, ecologists are well equipped to embrace the additional challenge of chemical complexity through interdisciplinary collaborations. This offers a unique opportunity to jointly advance a seminal frontier in pollution ecology and facilitate the development of innovative solutions for environmental protection.

Emerging Frontiers in Nanotechnology for Precision Agriculture: Advancements, Hurdles and Prospects

This review article provides an extensive overview of the emerging frontiers of nanotechnology in precision agriculture, highlighting recent advancements, hurdles, and prospects. The benefits of nanotechnology in this field include the development of advanced nanomaterials for enhanced seed germination and micronutrient supply, along with the alleviation of biotic and abiotic stress. Further, nanotechnology-based fertilizers and pesticides can be delivered in lower dosages, which reduces environmental impacts and human health hazards. Another significant advantage lies in introducing cutting-edge nanodiagnostic systems and nanobiosensors that monitor soil quality parameters, plant diseases, and stress, all of which are critical for precision agriculture. Additionally, this technology has demonstrated potential in reducing agro-waste, synthesizing high-value products, and using methods and devices for tagging, monitoring, and tracking agroproducts. Alongside these developments, cloud computing and smartphone-based biosensors have emerged as crucial data collection and analysis tools. Finally, this review delves into the economic, legal, social, and risk implications of nanotechnology in agriculture, which must be thoroughly examined for the technology’s widespread adoption.

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.

From lab to field: biological control of the Japanese beetle with entomopathogenic fungi

The Japanese beetle, Popillia japonica, is an invasive scarab and listed as quarantine organism in many countries worldwide. Native to Japan, it has invaded North America, the Azores, and recently mainland Europe. Adults are gregarious and cause agricultural and horticultural losses by feeding on leaves, fruits, and flowers of a wide range of crops and ornamental plants. Larvae feed belowground and damage grassland. To date, no efficient and environmentally friendly control measure is available. Larval populations of other scarab species such as Phyllopertha horticola and Melolontha melolontha are controlled by applying spores of the entomopathogenic fungi Metarhizium brunneum and Beauveria brongniartii to larval habitats. Here, we tested this control strategy against Japanese beetle larvae in grasslands, as well as spore spray applications against adults in crops. Using both, large-scale field experiments and inoculation experiments in the laboratory, we assess the efficacy of registered fungal strains against Japanese beetle larvae and adults. Metarhizium brunneum BIPESCO 5 established and persisted in the soil of larval habitats and on the leaves of adult's host plants after application. However, neither larval nor adult population sizes were reduced at the study sites. Laboratory experiments showed that larvae are not susceptible to M. brunneum ART 212, M. brunneum BIPESCO 5, and B. brongniartii BIPESCO 2. In contrast, adults were highly susceptible to all three strains. When blastospores were directly injected into the hemolymph, both adults and larvae showed elevated mortality rates, which suggests that the cuticle plays an important role in determining the difference in susceptibility of the two life stages. In conclusion, we do not see potential in adapting the state-of-the-art control strategy against native scarabs to Japanese beetle larvae. However, adults are susceptible to the tested entomopathogenic fungi in laboratory settings and BIPESCO 5 conidiospores survived for more than three weeks in the field despite UV-radiation and elevated temperatures. Hence, control of adults using fungi of the genera Beauveria or Metarhizium is more promising than larval control. Further research on efficient application methods and more virulent and locally adapted fungal strains will help to increase efficacy of fungal treatments for the control of P. japonica.

Sensitivity to imidacloprid insecticide varies among some social and solitary bee species of agricultural value

Pollinator health risks from long-lasting neonicotinoid insecticides like imidacloprid has primarily focused on commercially managed, cavity-nesting bees in the genera Apis, Bombus, and Osmia. We expand these assessments to include 12 species of native and non-native crop pollinators of differing levels of body size, sociality, and floral specialization. Bees were collected throughout 2016 and 2017 from flowering blueberry, squash, pumpkin, sunflower and okra in south Mississippi, USA. Within 30-60 minutes of capture, bees were installed in bioassay cages made from transparent plastic cups and dark amber jars. Bees were fed via dental wicks saturated with 27% (1.25 M) sugar syrup containing a realistic range of sublethal concentrations of imidacloprid (0, 5, 20, or 100 ppb) that are often found in nectar. Bees displayed no visible tremors or convulsions except for a small sweat bee, Halictus ligatus, and only at 100ppb syrup. Imidacloprid shortened the captive longevities of the solitary bees. Tolerant bee species lived ~10 to 12 days in the bioassays and included two social and one solitary species: Halictus ligatus, Apis mellifera and Ptilothrix bombiformis (rose mallow bees), respectively. No other bee species tolerated imidacloprid as well as honey bees did, which exhibited no appreciable mortality and only modest paralysis across concentration. In contrast, native bees either lived shorter lives, experienced longer paralysis, or endured both. Overall, longevity decreased with concentration linearly for social bees and non-linearly for solitary species. The percentage of a bee's captive lifespan spent paralyzed increased logarithmically with concentration for all species, although bumble bees suffered longest. Of greatest concern was comparable debilitation of agriculturally valuable solitary bees at both low and high sublethal rates of imidacloprid.

Neonicotinoid seed treatment on sugar beet in England: a qualitative analysis of the controversy, existing policy and viability of alternatives

In 2021, the United Kingdom Government granted the possibility of an emergency derogation for the use of the neonicotinoid seed treatment, thiamethoxam, on sugar beet in England. This was met with heavy criticism and controversy due to the body of evidence demonstrating toxicity of the insecticide to non-target species, particularly pollinators. However, many viewed this decision to be reasonable in this system, as sugar beet is a non-flowering crop, and derogations were only implemented if a set of conditions, including viral risk, were met. This research aims to understand the policy and the perspective of stakeholders in this debate, and identify key problems associated with thiamethoxam use on sugar beet. Semi-structured interviews combined with a modified policy analysis were used, incorporating framework analysis and comparative analysis. Political polarisation, whereby respondents felt that the debate had become anti-pesticide or pro-pesticide and lacked nuance, and the monopsony of British Sugar (a UK company that buys and processes sugar beet), were found to be the most prevalent issues currently impeding political progress and the enhancement of sustainable agriculture in this system. Virus forecasting was considered a successful strategy at the time of writing, although limitations to the model are also discussed. Non-chemical alternatives were found to be limited in this system due to the specificity of the pest system and the low threshold of virus yellows, while forecasting was considered to have the lowest net-environmental impact. Additional policy strategies to work alongside forecasting, such as public education and intergroup contact are also discussed. This study reflects a more general tug-of-war that often sets up a false dichotomy between food security and environmental sustainability. It highlights the importance of addressing the complexity of sustainable food production by opening up the discussion and taking a more nuanced and adaptive approach to policy.

Assessing availability of European plant protection product data: an example evaluating basic area treated

Besides the benefits of plant protection products (PPPs) for agricultural production, there is an increasing acknowledgement of the associated potential environmental risks. Here, we examine the feasibility of summarizing the extent of PPP usage at the country level, using Ireland as a case study, as well as at the European level. We used the area over which PPPs are applied (basic area) as an example variable that is relevant to initially assess the geographic extent of environmental risk. In Irish agricultural systems, which are primarily grass-based, herbicides fluroxypyr and glyphosate are the most widely applied active substances (ASs) in terms of basic area, followed by the fungicides chlorothalonil and prothioconazole that are closely associated with arable crops. Although all EU countries are subject to Regulation (EC) No 1185/2009, which sets the obligation of PPP usage data reporting at the national level, we only found usable data that met our criteria for Estonia, Germany, Finland, and Spain (4 of 30 countries reviewed). Overall, the most widely applied fungicide and herbicide in terms of basic area were prothioconazole (20%, 7% and 5% of national cultivated areas of Germany, Estonia and Ireland) and glyphosate (11%, 8% and 5% of national cultivated areas of Spain, Estonia and Ireland) respectively, although evaluations using application frequency may result in the observation of different trends. Several recommendations are proposed to tackle current data gaps and deficiencies in accessibility and usability of pesticide usage data across the EU in order to better inform environmental risk assessment and promote evidence-based policymaking.

Seed treatments containing neonicotinoids and fungicides reduce aquatic insect richness and abundance in midwestern USA-managed floodplain wetlands

Agrochemicals including neonicotinoid insecticides and fungicides are frequently applied as seed treatments on corn, soybeans, and other common row crops. Crops grown from pesticide-treated seed are often directly planted in managed floodplain wetlands and used as a soil disturbance or food resource for wildlife. We quantified invertebrate communities within mid-latitude floodplain wetlands and assessed their response to use of pesticide-treated seeds within the floodplain. We collected and tested aqueous and sediment samples for pesticides in addition to sampling aquatic invertebrates from 22 paired wetlands. Samples were collected twice in 2016 (spring [pre-water level drawdown] and autumn [post-water level flood-up]) followed by a third sampling period (spring 2017). Meanwhile, during the summer of 2016, a portion of study wetlands were planted with either pesticide-treated or untreated corn seed. Neonicotinoid toxic equivalencies (NI-EQs) for sediment (X̅ = 0.58 μg/kg), water (X̅ = 0.02 μg/L), and sediment fungicide concentrations (X̅ = 0.10 μg/kg) were used to assess potential effects on wetland invertebrates. An overall decrease in aquatic insect richness and abundance was associated with greater NI-EQs in wetland water and sediments, as well as with sediment fungicide concentration. Post-treatment, treated wetlands displayed a decrease in insect taxa-richness and abundance before recovering by the spring of 2017. Information on timing and magnitude of aquatic insect declines will be useful when considering the use of seed treatments for wildlife management. More broadly, this study brings attention to how agriculture is used in wetland management and conservation planning.

A Combined LD50 for Agrochemicals and Pathogens in Bumblebees (Bombus terrestris [Hymenoptera: Apidae])

Neonicotinoid insecticides are the most commonly used insecticide in the world and can have significant sub-lethal impacts on beneficial insects, including bumblebees, which are important pollinators of agricultural crops and wild-flowers. This has led to bans on neonicotinoid use in the EU and has resulted in repeated calls for the agrochemical regulatory process to be modified. For example, there is increasing concern about 1) the underrepresentation of wild bees, such as bumblebees, in the regulatory process, and 2) the failure to determine how agrochemicals, such as neonicotinoids, interact with other commonly occurring environmental stressors, such as parasites. Here, we modify an OECD approved lethal dose (LD50) experimental design and coexpose bumblebees (Bombus terrestris) to the neonicotinoid thiamethoxam and the highly prevalent trypanosome parasite Crithidia bombi, in a fully crossed design. We found no difference in the LD50 of thiamethoxam on bumblebees that had or had not been inoculated with the parasite (Crithidia bombi). Furthermore, thiamethoxam dosage did not appear to influence the parasite intensity of surviving bumblebees, and there was no effect of either parasite or insecticide on sucrose consumption. The methodology used demonstrates how existing ring-tested experimental designs can be effectively modified to include other environmental stressors such as parasites. Moving forward, the regulatory process should implement methodologies that assess the interactions between agrochemicals and parasites on non-Apis bees and, in cases when this is not practical, should implement post-regulatory monitoring to better understand the real-world consequences of agrochemical use.

Urinary neonicotinoid insecticides in children from South China: Concentrations, profiles and influencing factors

Neonicotinoid insecticides can selectively interact with the unique nicotinic acetylcholine receptor subtypes in insects and are considered to be low toxic to mammals. However, there is still insufficient knowledge on human exposure to neonicotinoid insecticides, especially for children. This study aimed to investigate urinary concentrations and profiles of neonicotinoid insecticides in South China children and to analyze potential influencing factors. Six neonicotinoid insecticides, including imidacloprid (IMI), thiamethoxam (THM), acetamiprid (ACE), clothianidin (CLO), thiacloprid (THD) and dinotefuran (DIN), exhibited high detection frequencies (>90%) in urine samples collected from 305 children, suggesting broad exposure in South China children. The median concentrations were determined to be 0.13, 0.21, 0.01, 0.19, 0.002 and 1.64 μg/L, respectively. Among the target neonicotinoids, urinary concentrations of CLO and THM exhibited a significant and positive correlation between each other (p < 0.05), suggesting similar sources of these two chemicals.

Host Plant Species Mediates Impact of Neonicotinoid Exposure to Monarch Butterflies

Simple Summary

Neonicotinoids are the most widely used insecticides in North America and many studies document the negative effects of neonicotinoids on bees. Monarch butterflies are famous for their long-distance migrations, and for their ability to sequester toxins from their milkweed host plants. The neonicotinoids imidacloprid and clothianidin were suggested to correlate with declines in North American monarchs. We examined how monarch development, survival, and flight were affected by exposure to neonicotinoids, and how these effects depend on milkweed host plant species that differ in their cardenolide toxins. Monarch survival and flight were unaffected by low and intermediate neonicotinoid doses. At the highest dose, neonicotinoids negatively affected monarch pupation and survival, for caterpillars that fed on the least toxic milkweed. Monarchs fed milkweed of intermediate toxicity experienced moderate negative effects of high insecticide doses. Monarchs fed the most toxic milkweed species had no negative consequences associated with neonicotinoid treatment. Our work shows that monarchs tolerate low neonicotinoid doses, but experience detrimental effects at higher doses, depending on milkweed species. To our knowledge, this is the first study to show that host plant species potentially reduce the residue of neonicotinoid insecticides on the leaf surface, and this phenomenon warrants further investigation.

Abstract

Neonicotinoids are the most widely used insecticides in North America. Numerous studies document the negative effects of neonicotinoids on bees, and it remains crucial to demonstrate if neonicotinoids affect other non-target insects, such as butterflies. Here we examine how two neonicotinoids (imidacloprid and clothianidin) affect the development, survival, and flight of monarch butterflies, and how these chemicals interact with the monarch’s milkweed host plant. We first fed caterpillars field-relevant low doses (0.075 and 0.225 ng/g) of neonicotinoids applied to milkweed leaves (Asclepias incarnata), and found no significant reductions in larval development rate, pre-adult survival, or adult flight performance. We next fed larvae higher neonicotinoid doses (4–70 ng/g) and reared them on milkweed species known to produce low, moderate, or high levels of secondary toxins (cardenolides). Monarchs exposed to the highest dose of clothianidin (51–70 ng/g) experienced pupal deformity, low survival to eclosion, smaller body size, and weaker adult grip strength. This effect was most evident for monarchs reared on the lowest cardenolide milkweed (A. incarnata), whereas monarchs reared on the high-cardenolide A. curassavica showed no significant reductions in any variable measured. Our results indicate that monarchs are tolerant to low doses of neonicotinoid, and that negative impacts of neonicotinoids depend on host plant type. Plant toxins may confer protective effects or leaf physical properties may affect chemical retention. Although neonicotinoid residues are ubiquitous on milkweeds in agricultural and ornamental settings, commonly encountered doses below 50 ng/g are unlikely to cause substantial declines in monarch survival or migratory performance.

Exposure of wild boars (Sus scrofa L) to neonicotinoid insecticides

The aim was to determine, for the first time, concentrations of 7 neonicotinoids (NEOs) and 5 metabolites in Sus scrofa from hunting areas in north-eastern Poland and assess the risk to consumers eating boar meat. 42 wild boar muscle samples were collected over a one-year period. The concentrations of 12 NEOs were determined by a fully validated LC-ESI-MS/MS protocol based on ultrasonic, freezing and cleanup EMR-lipid sample preparation. NEOs were present in over 83% of samples, 17% had no residue, and one pesticide was present in 36% of samples. Most often found were: clothianidin (35%), acetamiprid and imidacloprid (33%), thiacloprid (31%), thiamethoxam (9%), and the average concentrations were (ng g^-1): thiacloprid 6.2 > imidacloprid 5.7 > acetamiprid 4.6 > clothianidin 2.2 > thiacloprid 1.6 > thiamethoxam 1.0. Multi-residue samples were found, one with 7 and one with 5 NEOs. Two NEOs were present in 24%; 3 in 39% and 4 in 10% of samples. In the metabolic degradation of acetamiprid, imidacloprid and thiacloprid, it was observed that metabolites account for no more than 8.5% of the measured parent substance. Acetamiprid-n-desmethyl was noted most often (21%). Due to the detection of NEOs in a large proportion of samples, chronic and acute risk assessment were performed. The estimated chronic and acute risk for consumers from NEOs neonicotinoids through the consumption of wild boar was very low and amounted to respectively 0.02% of ADI and 0.86% of ARfD.

Evaluating the role of insecticidal seed treatment and refuge for managing soybean aphid virulence

BACKGROUND

Managing insect virulence can extend the durability of host-plant resistant crops. Genetically modified resistant crops continue to be successful because of insect-resistant management strategies that delay resistance such as multiple toxins and a susceptible refuge. These strategies may also be useful for host-plant resistant crops, but more research is needed on their applicability. We investigated the interaction between a susceptible refuge and an insecticidal seed treatment to manage virulence in the soybean aphid. We tested four scenarios of an insecticidal seed treatment (plus an untreated control) in a microcosm containing 25% aphid-susceptible (refuge) and 75% aphid-resistant soybeans. Independent cohorts of plants were infested every week with avirulent and virulent aphids at equal frequencies. We used a molecular marker to estimate the change in virulence frequency across different plant maturities (from 7 to 42 days after planting).

RESULTS

The presence of an insecticidal seed treatment on either the susceptible or resistant soybean decreased the overall population size of the soybean aphid. However, the insecticidal seed treatment impacted both virulent and avirulent aphids similarly, and only altered frequencies in favor of virulence when the sole susceptible plant (i.e., refuge) was treated.

CONCLUSION

Under our experimental conditions, the frequency of avirulent aphids persisted with the use of a refuge. Although an insecticidal seed treatment decreased the overall aphid population size, it did not appear to benefit virulence management. © 2021 Society of Chemical Industry.

Clothianidin decomposition in Missouri wetland soils

Neonicotinoid pesticides can persist in soils for extended time periods; however, they also have a high potential to contaminate ground and surface waters. Studies have reported negative effects associated with neonicotinoids and nontarget taxa, including aquatic invertebrates, pollinating insect species, and insectivorous birds. This study evaluated factors associated with clothianidin (CTN) degradation and sorption in Missouri wetland soils to assess the potential for wetland soils to mitigate potential environmental risks associated with neonicotinoids. Solid-to-solution partition coefficients (K_d ) for CTN sorption to eight wetland soils were determined via single-point sorption experiments, and sorption isotherm experiments were conducted using the two most contrasting soils. Clothianidin degradation was determined under oxic and anoxic conditions over 60 d. Degradation data were fit to zero- and first-order kinetic decay models to determine CTN half-life (t_0.5 ). Sorption results indicated CTN sorption to wetland soil was relatively weak (average K_d , 3.58 L kg^-1 ); thus, CTN has the potential to be mobile and bioavailable within wetland soils. However, incubation results showed anoxic conditions significantly increased CTN degradation rates in wetland soils (anoxic average t_0.5 , 27.2 d; oxic average t_0.5 , 149.1 d). A significant negative correlation was observed between anoxic half-life values and soil organic C content (r²  = .782; p = .046). Greater CTN degradation rates in wetland soils under anoxic conditions suggest that managing wetlands to facilitate anoxic conditions could mitigate CTN presence in the environment and reduce exposure to nontarget organisms.

Beyond the Headlines: The Influence of Insurance Pest Management on an Unseen, Silent Entomological Majority

For most of the last two decades, insect pest management in key grain and oilseed crops has relied heavily on an insurance-based approach. This approach mandates a suite of management tactics prior to planting and in the absence of pest data. Because there is little flexibility for using these tactics individually, most producers have adopted this full suite of practices despite mounting evidence that some components do not provide consistent benefits. In North America in particular, this preventive approach to insect pest management has led to steep increases in use of neonicotinoid insecticides and subsequent increases in neonicotinoids in soil and water within crop fields and beyond. These increases have been accompanied by a host of non-target effects that have been most clearly studied in pollinators and insect natural enemies. Less attention has been given to the effects of this practice upon the many thousands of aquatic insect species that are often cryptic and offer negligible, or undefined, clear benefits to humans and their commerce. A survey of the literature reveals that the non-target effects of neonicotinoids upon these aquatic species are often as serious as for terrestrial species, and more difficult to address. By focusing upon charismatic insect species that provide clearly defined services, we are likely dramatically under-estimating the effects of neonicotinoids upon the wider environment. Given the mounting evidence base demonstrating that the pest management and crop yield benefits of this approach are negligible, we advocate for a return to largely-abandoned IPM principles as a readily accessible alternative path.

Population viability in a host-parasitoid system is mediated by interactions between population stage structure and life stage differential susceptibility to toxicants

The effects of toxicants, such as pesticides, may be more severe for some life stages of an organism than others. However, in most toxicity studies, data is developed for only one life stage, which may lead to misleading interpretations. Furthermore, population stage-structure may interact with differential susceptibility, especially when populations consist of higher proportions of individuals in more susceptible stages at the time of toxicant exposure. We explore the interaction of differential stage susceptibility and stage distribution using a stage-structured Lefkovitch matrix model. We incorporate lab-derived toxicity data for a common parasitoid, the braconid Diaeretiella rapae (M’Intosh), a common natural enemy of the cabbage aphid (Brevicoryne brassicae L.), exposed to the pesticide imidacloprid. We compare population outcomes of simulations in which we vary both the population stage structure along with the susceptibility of each stage to toxicants. Our results illustrate an interaction between differential susceptibility and initial stage distribution, highlighting the fact that both of these demographic features should be considered in interpreting toxicity data and the development of ecological risk assessments.

Beyond neonicotinoids - Wild pollinators are exposed to a range of pesticides while foraging in agroecosystems

Pesticide exposure is a growing global concern for pollinator conservation. While most current pesticide studies have specifically focused on the impacts of neonicotinoid insecticides toward honeybees and some native bee species, wild pollinators may be exposed to a broader range of agrochemicals. In 2016 and 2017 we collected a total of 637 wild bees and butterflies from the margins of cultivated agricultural fields situated on five Conservation Areas in mid-northern Missouri. Pollinators were composited by individual genera (90 samples) and whole tissues were then analyzed for the presence of 168 pesticides and degradation products. At least one pesticide was detected (% frequency) in the following wild bee genera: Bombus (96%), Eucera (75%), Melissodes (73%), Ptilothrix (50%), Xylocopa (50%), and Megachile (17%). Similarly, at least one pesticide was detected in the following lepidopteran genera: Hemaris (100%), Hylephila (75%), Danaus (60%), and Colias (50%). Active ingredients detected in >2% of overall pollinator samples were as follows: metolachlor (24%), tebuconazole (22%), atrazine (18%), imidacloprid desnitro (13%), bifenthrin (9%), flumetralin (9%), p, p'-DDD (6%), tebupirimfos (4%), fludioxonil (4%), flutriafol (3%), cyproconazole (2%), and oxadiazon (2%). Concentrations of individual pesticides ranged from 2 to 174 ng/g. Results of this pilot field study indicate that wild pollinators are exposed to and are potentially bioaccumulating a wide variety of pesticides in addition to neonicotinoids. Here, we provide evidence that wild bee and butterfly genera may face exposure to a wide range of insecticides, fungicides, and herbicides despite being collected from areas managed for conservation. Therefore, even with the presence of extensive habitat, minimal agricultural activity on Conservation Areas may expose pollinators to a range of pesticides.

Known Target and Nontarget Effects of the Novel Neonicotinoid Cycloxaprid to Arthropods: A Systematic Review

Neonicotinoids are the most widely used insecticide class worldwide, and unfortunately, the widely used neonicotinoid imidacloprid is problematic for pollinators and other nontarget organisms. These nontarget impacts and the development of resistance prompt the ongoing development and testing of new neonicotinoids. The novel neonicotinoid cycloxaprid was described in 2011 and registered in China in 2015. Studies investigating its use and effect on target and nontarget species are recent and ongoing, and empirical evidence has not yet been collectively considered. Therefore, a systematic review was performed to identify and summarize data associated with target and nontarget, lethal and sublethal impacts of cycloxaprid for its use as a new insecticide. We performed keyword literature searches in Web of Science, PubMed, Academic Search Complete, and Google Scholar and explored citations used in identified articles. The search strategy yielded 66 citations; 25 citations fulfilled eligibility criteria and were included in the review. Under experimental conditions, cycloxaprid reduced populations of plant-feeding insect pests, suppressed populations of sucking and biting insect pests, and affected reproduction, development time, longevity, growth, gene regulation and expression, and phloem-feeding behavior of various life stages of certain insects. Studies focus on pest control efficacy and comparison with imidacloprid. Five nontarget organisms have been evaluated: Apis mellifera, Chrysoperla sinica, Harmonia axyridis, Daphnia magna, and Eisenia fetida. Variation in study design, to date, precludes a metaanalysis. However, these results provide valuable insight into possible effects to target and nontarget arthropods. Because cycloxaprid is a new insecticide, additional research is needed to clarify the mechanism of action of cycloxaprid and its metabolites, and to determine if it harms natural enemies or other nontarget organisms, if resistance develops, and if it exhibits cross-resistance with other insecticides. Although research on target arthropods will inform some effects on nontarget organisms, studies focusing explicitly on impacts to nontarget organisms are needed. Integr Environ Assess Manag 2020;16:831-840. © 2020 SETAC.

Genetic Variation Influences Tolerance to a Neonicotinoid Insecticide in 3 Butterfly Species

Neonicotinoid pesticides harm nontarget insects, but their sublethal effects on butterflies are understudied. We exposed larvae of 3 butterfly species (Pieris rapae, Colias philodice, and Danaus plexippus) to low levels of the neonicotinoid imidacloprid in their host plants and followed individuals to adulthood. Imidacloprid altered adult body size, especially in female monarchs, but its effects varied across maternal families, highlighting the importance of considering genetic variation in ecotoxicological testing. Environ Toxicol Chem 2020;39:2228-2236. © 2020 SETAC.

Exposure Level of Neonicotinoid Insecticides in the Food Chain and the Evaluation of Their Human Health Impact and Environmental Risk: An Overview

Neonicotinoid insecticides (neonics) were the most rapidly growing class of insecticides over the past few decades, and are used mainly for vegetables, fruits, and grains. Although neonics exhibit lower toxicity in mammals and humans compared to traditional insecticides, increasing numbers of studies are demonstrating that neonics may accumulate in the food chain and environmental media. Long-term exposure to neonics may raise potential risks to animals and even to humans. The present report reviews the development, application, and prohibition of neonics in the farmland ecosystem, and summarizes the exposure level and harmful effects of these insecticides in the food chain. In addition, the present review analyzes and summarizes the evaluation of the human health impact and environmental risk of the neonics, and overviews the unresolved problems and future research directions in this field. The aim of the present report was to review the exposure level, potential toxicity, human health impact, and environmental risk assessment of neonics in various media in order to provide reliable technical support for strengthening the environmental and food safety supervision and green pesticide designing.

Larval pesticide exposure impacts monarch butterfly performance

The long-term decline of monarch butterflies has been attributed to loss of their milkweed (Asclepias sp.) host-plants after the introduction of herbicide-tolerant crops. However, recent studies report pesticide residues on milkweed leaves that could act as a contributing factor when ingested as part of their larval diet. In this study, we exposed monarch larvae to six pesticides (insecticide: clothianidin; herbicides: atrazine, S-metolachlor; fungicides: azoxystrobin, pyraclostrobin, trifloxystrobin) on their primary host-plant, A. syriaca. Each was tested at mean and maximum levels reported from published analyses of milkweeds bordering cropland and thus represent field-relevant concentrations. Monarch lethal and sub-lethal responses were tracked over their complete development, from early instar larvae to adult death. Overall, we found no impact of any pesticide on immature development time and relatively weak effects on larval herbivory or survival to adulthood. Comparatively stronger effects were detected for adult performance; namely, a 12.5% reduction in wing length in response to the fungicides azoxystrobin and trifloxystrobin. These data collectively suggest that monarch responses to host-plant pesticides are largely sublethal and more pronounced in the adult stage, despite exposure only as larvae. This outcome has important implications for risk assessment and the migratory success of monarchs in North America.

Influence of a Neonicotinoid Seed Treatment on a Nontarget Herbivore of Soybean (Twospotted Spider Mite) and Diet Switching by a Co-occurring Omnivore (Western Flower Thrips)

Insecticidal neonicotinoid seed treatments are a common agricultural insect pest management strategy; however, effects on nontarget pests and omnivorous arthropods are understudied. We used a series of experiments to evaluate impacts of the neonicotinoid seed treatment thiamethoxam on densities of herbivorous twospotted spider mites (Tetranychus urticae Koch [Acari: Tetranychidae]) and feeding behavior of western flower thrips (Frankliniella occidentalis Pergande [Thysanoptera: Thripidae]), an omnivore that feeds on spider mite eggs but is also a significant plant pest. Spider mite densities were higher on neonicotinoid-treated soybeans, but only when mites were not spatially confined. We then examined how availability of thiamethoxam-treated food items (i.e., eggs from spider mites reared on treated soybeans, soybean leaf discs, or a combination of the two), and previous exposure to thiamethoxam-treated soybean impacted thrips feeding. Regardless of the presence of leaf tissue, thrips consumed fewer spider mite eggs laid by females reared on treated soybeans, suggesting spider mite eggs can serve as poisoned prey. Overall, thrips consumed less treated soybean leaf tissue, and thrips on treated leaf discs had a lower percentage of herbivorous feeding events and consumed more nontreated spider mite eggs, indicating a dietary shift from herbivory to predation. The neonicotinoid status of spider mite eggs and prior exposure of thrips also caused shifts in the number and size of leaf scars, likely as a result of altered foraging behavior and/or movement. Shifts between herbivory and predation have implications for thrips damage, virus transmission, and pest management, especially in systems with mixtures of nontreated and neonicotinoid-treated plants.

Toxicity evaluation of the active ingredient acetamiprid and a commercial formulation (Assail® 70) on the non-target gastropod Biomphalaria straminea (Mollusca: Planorbidae)

Neonicotinoids emerged as an environmentally safe alternative to previous generations of insecticides becoming one of the most widely applied in modern agriculture. Nevertheless, they have been reported to affect several non-target organisms. Most toxicity studies focus on the effects on pollinators or terrestrial invertebrates and evaluate either the active ingredient or the commercial formulation. In the present study, we aimed to assess the long-term effects of the active ingredient acetamiprid and a broadly used commercial formulation (Assail® 70) on the non-target freshwater gastropod Biomphalaria straminea using a battery of biomarkers. A 14 day-exposure of adult organisms to both active ingredient and commercial formulation increased carboxylesterase activity and glutathione content, inhibited superoxide dismutase activity and decreased reactive oxygen species levels. The commercial formulation additionally increased glutathione S-transferase activity and inhibited catalase activity. The results indicate a greater toxicity of the commercial formulation than that of the active ingredient alone. Cholinesterase activity, development and offspring survival of B. straminea were not impaired. We conclude that the toxicity of acetamiprid on this gastropod species is mainly related to effects on detoxification and oxidative metabolism responses. This study provides novel information about the adverse effects of the active ingredient and a commercial formulation of a widely used neonicotinoid on a non-target aquatic species.

Impact of Imidacloprid Soil Drenching on Survival, Longevity, and Reproduction of the Zoophytophagous Predator Podisus maculiventris (Hemiptera: Pentatomidae: Asopinae)

Systemic insecticides when applied as seed treatments or soil drenches are often more toxicologically selective for natural enemies than target pests. This may not be the case, however, for omnivorous predators, which are at risk of extended exposure to systemically applied pesticides through ingestion while feeding on treated plants for nutrients or water. Such exposure may kill or have sublethal consequences for these natural enemies, compromising their role as biocontrol agents of agricultural pest species. The spined soldier bug, Podisus maculiventris (Say) (Hemiptera: Pentatomidae: Asopinae), is an important zoophytophagous biocontrol agent (i.e., able to substitute zoophagy by phytophagy for survival) that may be exposed to systemic insecticides in many agricultural systems. We, therefore, examined effects on P. maculiventris following exposure to cabbage plants subject to soil-drench treatments with imidacloprid, a systemic neonicotinoid insecticide. Predator survival, development, body weight, and reproduction were recorded. Imidacloprid significantly affected nymph survival and adult emergence, but not duration of the nymphal period or adult body weight. At one-twentieth the recommended field rate for whitefly and aphid management, imidacloprid treatments reduced longevity, fecundity, and fertility of female predators. These findings demonstrate that soil treatments with systemic insecticide can negatively impact zoophytophagous natural enemies.

The Impact of Pesticides on Flower-Visiting Insects: A Review with Regard to European Risk Assessment

Flower-visiting insects (FVIs) are an ecologically diverse group of mobile, flying species that should be protected from pesticide effects according to European policy. However, there is an ongoing decline of FVI species, partly caused by agricultural pesticide applications. Therefore, the risk assessment framework needs to be improved. We synthesized the peer-reviewed literature on FVI groups and their ecology, habitat, exposure to pesticides, and subsequent effects. The results show that FVIs are far more diverse than previously thought. Their habitat, the entire agricultural landscape, is potentially contaminated with pesticides through multiple pathways. Pesticide exposure of FVIs at environmentally realistic levels can cause population-relevant adverse effects. This knowledge was used to critically evaluate the European regulatory framework of exposure and effect assessment. The current risk assessment should be amended to incorporate specific ecological properties of FVIs, that is, traits. We present data-driven tools to improve future risk assessments by making use of trait information. There are major knowledge gaps concerning the general investigation of groups other than bees, the collection of comprehensive data on FVI groups and their ecology, linking habitat to FVI exposure, and study of previously neglected complex population effects. This is necessary to improve our understanding of FVIs and facilitate the development of a more protective FVI risk assessment. Environ Toxicol Chem 2019;38:2355-2370. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

A Neonicotinoid Insecticide at a Rate Found in Nectar Reduces Longevity but Not Oogenesis in Monarch Butterflies, Danaus plexippus (L.). (Lepidoptera: Nymphalidae)

The monarch butterfly in North America has suffered a serious population decline since the mid-1990s. The introduction and widespread use of neonicotinoid insecticides during the same time period has been suggested as a potential driver of this decline but no studies have looked at the impact of these insecticides on adult monarchs. A brief laboratory study assessed the impact of Imidacloprid, the most commonly used neonicotinoid, on western monarch butterfly longevity and oogenesis. Imidacloprid at 23.5 ppb, a field-realistic rate reported from wild nectar and pollen, was fed ad libitum to newly-eclosed monarchs in a sugar-based diet for 22 days. Treated monarchs showed reduced longevity, suffering 78.8% mortality by day 22, compared to 20% in untreated monarchs. Prior to death, butterflies exhibited signs of poisoning including uncoordinated flapping of wings and uncontrolled vibrating of wings and body. Imidacloprid did not reduce egg production. Shortened adult longevity has serious consequences for monarch population development, migration and overwintering. The potential widespread impact of imidacloprid-contaminated crop and wild flower nectar, may be a significant driver of monarch population decline. More research on the impact of neonicotinoid insecticides on the monarch and other butterflies should be viewed as a serious priority.

No evidence for negative impacts of acute sulfoxaflor exposure on bee olfactory conditioning or working memory

Systemic insecticides such as neonicotinoids and sulfoximines can be present in the nectar and pollen of treated crops, through which foraging bees can become acutely exposed. Research has shown that acute, field realistic dosages of neonicotinoids can negatively influence bee learning and memory, with potential consequences for bee behaviour. As legislative reassessment of neonicotinoid use occurs globally, there is an urgent need to understand the potential risk of other systemic insecticides. Sulfoxaflor, the first branded sulfoximine-based insecticide, has the same mode of action as neonicotinoids, and may potentially replace them over large geographical ranges. Here we assessed the impact of acute sulfoxaflor exposure on performance in two paradigms that have previously been used to illustrate negative impacts of neonicotinoid pesticides on bee learning and memory. We assayed whether acute sulfoxaflor exposure influences (a) olfactory conditioning performance in both bumblebees (Bombus terrestris) and honeybees (Apis mellifera), using a proboscis extension reflex assay, and (b) working memory performance of bumblebees, using a radial-arm maze. We found no evidence to suggest that sulfoxaflor influenced performance in either paradigm. Our results suggest that despite a shared mode of action between sulfoxaflor and neonicotinoid-based insecticides, widely-documented effects of neonicotinoids on bee cognition may not be observed with sulfoxaflor, at least at acute exposure regimes.

Quantifying the impact of pesticides on learning and memory in bees

Most insecticides are insect neurotoxins. Evidence is emerging that sublethal doses of these neurotoxins are affecting the learning and memory of both wild and managed bee colonies, exacerbating the negative effects of pesticide exposure and reducing individual foraging efficiency.

Variation in methodologies and interpretation of results across studies has precluded the quantitative evaluation of these impacts that is needed to make recommendations for policy change. It is not clear whether robust effects occur under acute exposure regimes (often argued to be more field‐realistic than the chronic regimes upon which many studies are based), for field‐realistic dosages, and for pesticides other than neonicotinoids.

Here we use meta‐analysis to examine the impact of pesticides on bee performance in proboscis extension‐based learning assays, the paradigm most commonly used to assess learning and memory in bees. We draw together 104 (learning) and 167 (memory) estimated effect sizes across a diverse range of studies.

We detected significant negative effects of pesticides on learning and memory (i) at field realistic dosages, (ii) under both chronic and acute application, and (iii) for both neonicotinoid and non‐neonicotinoid pesticides groups.

We also expose key gaps in the literature that include a critical lack of studies on non‐Apis bees, on larval exposure (potentially one of the major exposure routes), and on performance in alternative learning paradigms.

Policy implications. Procedures for the registration of new pesticides within EU member states now typically require assessment of risks to pollinators if potential target crops are attractive to bees. However, our results provide robust quantitative evidence for subtle, sublethal effects, the consequences of which are unlikely to be detected within small‐scale prelicensing laboratory or field trials, but can be critical when pesticides are used at a landscape scale. Our findings highlight the need for long‐term postlicensing environmental safety monitoring as a requirement within licensing policy for plant protection products.

A synoptic survey of select wastewater-tracer compounds and the pesticide imidacloprid in Florida's ambient freshwaters

Current wastewater treatment technologies do not remove many unregulated hydrophilic compounds, and there is growing interest that low levels of these compounds, referred to as emerging contaminants, may impact human health and the environment. A probabilistic-designed monitoring network was employed to infer the extent of Florida's ambient freshwaters containing the wastewater (Includes reuse water, septic systems leachate, and wastewater treatment effluent.) indicators sucralose, acetaminophen, carbamazepine, and primidone and those containing the widely used pesticide imidacloprid. Extent estimates with 95% confidence bounds are provided for canals, rivers, streams, small and large lakes, and unconfined aquifers containing ultra-trace concentrations of these compounds as based on analyses of 2015 sample surveys utilizing 528 sites. Sucralose is estimated to occur in greater than 50% of the canal, river, stream, and large lake resource extents. The pharmaceuticals acetaminophen, carbamazepine, and primidone are most prevalent in rivers, with approximately 30% of river kilometers estimated to contain at least one of these compounds. Imidacloprid is estimated to occur in 50% or greater of the canal and river resource extents, and it is the only compound found to exceed published toxicity or environmental effects standards. Geospatial analyses show sucralose detection frequencies within Florida's drainage basins to be significantly related to the percentage of urban land use (R² = 0.36, p < 0.001), and imidacloprid detection frequencies to be significantly related to the percentage of urban and agricultural land use (R² = 0.47, p < 0.001). The extent of the presence of these compounds highlights the need for additional emerging contaminant studies especially those examining effects on aquatic biota.