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Neonicotinoid seed coating is associated with reduced density of wild bees, as well as reduced nesting of solitary bees and reduced colony growth and reproduction of bumblebees, but appears not to affect honeybees. Bees' responses to neonicotinoids examined Reports that neonicotinoid insecticides have adverse effects on bee populations remain controversial. Some studies have been criticized as using unrealistically high insecticide dosages or conditions far removed from those in the field, and it has been suggested that bees might be able to detect the insecticides and avoid treated crops. Two papers in this issue of Nature present results that fill some of the gaps in our knowledge. In laboratory experiments Sébastien Kessler et al . use field-level doses of three commonly used neonicotinoids — clothianidin, imidacloprid and thiamethoxam — to show that both honeybees and bumblebees are able to detect their presence. However, the bees do not avoid neonicotinoid-treated food and may even prefer it. Maj Rundlöf et al . sowed oilseed rape with and without a clothianidin seed coating in matched and replicated agricultural landscapes. They found the seed coating to be associated with reduced density of wild bees, as well as reduced nesting of solitary bees and reduced colony growth of bumblebees, but they did not detect an effect on honeybees. Understanding the effects of neonicotinoid insecticides on bees is vital because of reported declines in bee diversity and distribution 1 , 2 , 3 and the crucial role bees have as pollinators in ecosystems and agriculture 4 . Neonicotinoids are suspected to pose an unacceptable risk to bees, partly because of their systemic uptake in plants 5 , and the European Union has therefore introduced a moratorium on three neonicotinoids as seed coatings in flowering crops that attract bees 6 . The moratorium has been criticized for being based on weak evidence 7 , particularly because effects have mostly been measured on bees that have been artificially fed neonicotinoids 8 , 9 , 10 , 11 . Thus, the key question is how neonicotinoids influence bees, and wild bees in particular, in real-world agricultural landscapes 11 , 12 , 13 . Here we show that a commonly used insecticide seed coating in a flowering crop can have serious consequences for wild bees. In a study with replicated and matched landscapes, we found that seed coating with Elado, an insecticide containing a combination of the neonicotinoid clothianidin and the non-systemic pyrethroid β-cyfluthrin, applied to oilseed rape seeds, reduced wild bee density, solitary bee nesting, and bumblebee colony growth and reproduction under field conditions. Hence, such insecticidal use can pose a substantial risk to wild bees in agricultural landscapes, and the contribution of pesticides to the global decline of wild bees 1 , 2 , 3 may have been underestimated. The lack of a significant response in honeybee colonies suggests that reported pesticide effects on honeybees cannot always be extrapolated to wild bees.

Pyrethroid insecticides are widely used as one of the most effective control measures in the global fight against agricultural arthropod pests and mosquito-borne diseases, including malaria and dengue. They exert toxic effects by altering the function of voltage-gated sodium channels, which are essential for proper electrical signaling in the nervous system. A major threat to the sustained use of pyrethroids for vector control is the emergence of mosquito resistance to pyrethroids worldwide. Here, we report the successful expression of a sodium channel, AaNa ᵥ1–1, from Aedes aegypti in Xenopus oocytes, and the functional examination of nine sodium channel mutations that are associated with pyrethroid resistance in various Ae. aegypti and Anopheles gambiae populations around the world. Our analysis shows that five of the nine mutations reduce AaNa ᵥ1–1 sensitivity to pyrethroids. Computer modeling and further mutational analysis revealed a surprising finding: Although two of the five confirmed mutations map to a previously proposed pyrethroid-receptor site in the house fly sodium channel, the other three mutations are mapped to a second receptor site. Discovery of this second putative receptor site provides a dual-receptor paradigm that could explain much of the molecular mechanisms of pyrethroid action and resistance as well as the high selectivity of pyrethroids on insect vs. mammalian sodium channels. Results from this study could impact future prediction and monitoring of pyrethroid resistance in mosquitoes and other arthropod pests and disease vectors.

Mitigating the threat of insecticide resistance in African malaria vector populations requires comprehensive information about where resistance occurs, to what degree, and how this has changed over time. Estimating these trends is complicated by the sparse, heterogeneous distribution of observations of resistance phenotypes in field populations. We use 6,423 observations of the prevalence of resistance to the most important vector control insecticides to inform a Bayesian geostatistical ensemble modelling approach, generating fine-scale predictive maps of resistance phenotypes in mosquitoes from the Anopheles gambiae complex across Africa. Our models are informed by a suite of 111 predictor variables describing potential drivers of selection for resistance. Our maps show alarming increases in the prevalence of resistance to pyrethroids and DDT across sub-Saharan Africa from 2005 to 2017, with mean mortality following insecticide exposure declining from almost 100% to less than 30% in some areas, as well as substantial spatial variation in resistance trends.

Gestational exposure to several common agricultural pesticides can induce developmental neurotoxicity in humans, and has been associated with developmental delay and autism. We evaluated whether residential proximity to agricultural pesticides during pregnancy is associated with autism spectrum disorders (ASD) or developmental delay (DD) in the Childhood Autism Risks from Genetics and Environment (CHARGE) study. The CHARGE study is a population-based case-control study of ASD, DD, and typical development. For 970 participants, commercial pesticide application data from the California Pesticide Use Report (1997-2008) were linked to the addresses during pregnancy. Pounds of active ingredient applied for organophophates, organochlorines, pyrethroids, and carbamates were aggregated within 1.25-km, 1.5-km, and 1.75-km buffer distances from the home. Multinomial logistic regression was used to estimate the odds ratio (OR) of exposure comparing confirmed cases of ASD (n = 486) or DD (n = 168) with typically developing referents (n = 316). Approximately one-third of CHARGE study mothers lived, during pregnancy, within 1.5 km (just under 1 mile) of an agricultural pesticide application. Proximity to organophosphates at some point during gestation was associated with a 60% increased risk for ASD, higher for third-trimester exposures (OR = 2.0; 95% CI: 1.1, 3.6), and second-trimester chlorpyrifos applications (OR = 3.3; 95% CI: 1.5, 7.4). Children of mothers residing near pyrethroid insecticide applications just before conception or during third trimester were at greater risk for both ASD and DD, with ORs ranging from 1.7 to 2.3. Risk for DD was increased in those near carbamate applications, but no specific vulnerable period was identified. This study of ASD strengthens the evidence linking neurodevelopmental disorders with gestational pesticide exposures, particularly organophosphates, and provides novel results of ASD and DD associations with, respectively, pyrethroids and carbamates.

Synthetic pyrethroid insecticides were introduced into widespread use for the control of insect pests and disease vectors more than three decades ago. In addition to their value in controlling agricultural pests, pyrethroids are at the forefront of efforts to combat malaria and other mosquito-borne diseases and are also common ingredients of household insecticide and companion animal ectoparasite control products. The abundance and variety of pyrethroid uses contribute to the risk of exposure and adverse effects in the general population. The insecticidal actions of pyrethroids depend on their ability to bind to and disrupt voltage-gated sodium channels of insect nerves. Sodium channels are also important targets for the neurotoxic effects of pyrethroids in mammals but other targets, particularly voltage-gated calcium and chloride channels, have been implicated as alternative or secondary sites of action for a subset of pyrethroids. This review summarizes information published during the past decade on the action of pyrethroids on voltage-gated sodium channels as well as on voltage-gated calcium and chloride channels and provides a critical re-evaluation of the role of these three targets in pyrethroid neurotoxicity based on this information.

Recent efforts to evaluate the contribution of neonicotinoid insecticides to worldwide pollinator declines have focused on honey bees and the chronic levels of exposure experienced when foraging on crops grown from neonicotinoid-treated seeds. However, few studies address non-crop plants as a potential route of pollinator exposure to neonicotinoid and other insecticides. Here we show that pollen collected by honey bee foragers in maize- and soybean-dominated landscapes is contaminated throughout the growing season with multiple agricultural pesticides, including the neonicotinoids used as seed treatments. Notably, however, the highest levels of contamination in pollen are pyrethroid insecticides targeting mosquitoes and other nuisance pests. Furthermore, pollen from crop plants represents only a tiny fraction of the total diversity of pollen resources used by honey bees in these landscapes, with the principle sources of pollen originating from non-cultivated plants. These findings provide fundamental information about the foraging habits of honey bees in these landscapes. The extent to which non-crop plants may be contaminated by insecticides is not known. Here, the authors show that pollen collected by honey bees living in areas of intensive maize production is contaminated by a wide range of pesticides throughout the growing season, with the principle pollen source being non-crop plants.

Environmental contamination from toxic metals and pesticides is an issue of great concern due to their harmful effects to human health and the ecosystems. In this framework, we assessed the adverse effects when aquatic organisms are exposed to toxicants such as deltamethrin (DM) and lead (Pb), alone or in combination, using zebrafish as a model. Moreover, we likewise evaluated the possible protective effect of vitamin C (VC) supplementation against the combined acute toxic effects of the two toxicants. Juvenile zebrafish were exposed to DM (2 μg L−1) and Pb (60 μg L−1) alone and in combination with VC (100 μg L−1) and responses were assessed by quantifying acetylcholinesterase (AChE) activity, lipid peroxidation (MDA), some antioxidant enzyme activities (SOD and GPx), three-dimension locomotion responses and changes of elements concentrations in the zebrafish body. Our results show that VC has mitigative effects against behavioral and biochemical alterations induced by a mixture of contaminants, demonstrating that it can be used as an effective antioxidant. Moreover, the observations in the study demonstrate zebrafish as a promising in vivo model for assessing the neuroprotective actions of bioactive compounds.

The yellow-legged hornet, Vespa velutina subs. nigrithorax Buysson, 1905, originally from Southeast Asia, has become an invasive species in Europe since its introduction in France around 2004. Its rapid proliferation and voracious predatory behavior pose a significant threat to native insects, particularly honeybees and other pollinators, impacting agricultural production, biodiversity, and human safety. Eradication in Europe seems now impossible, and the control efforts are hindered by the lack of standardized application protocols, including for insecticide use, leading to potential indiscriminate pesticide application and, consequently, environmental damages. Our study evaluated the acute contact toxicity on V. v. nigrithorax workers of four commercially available formulations containing acetamiprid, cypermethrin, a mix of natural pyrethrins, and Spinosad as active ingredients. These tests were performed in laboratory conditions, offering novel data for the chemical control of this invasive species. Our results suggest acetamiprid and spinosad as promising candidates for the yellow-legged hornet control. Further research is needed to validate their efficacy under field conditions and assess ecological impacts of these pesticides on non-target organisms. Integrated pest management strategies should prioritize insecticides with low non-target toxicity and minimal environmental persistence to mitigate resistance development and ensure effective pest control. Comprehensive assessments considering multiple factors beyond mortality are essential for informing sustainable pest control strategies.

As an important pest on winter wheat, Rhopalosiphum padi (L.) causes damage to the wheat yield by sucking plant nutrients, transmitting plant viruses and producing mildew. R. padi has been reported to develop resistance to pyrethroids and neonicotinoids. To explore potential alternative approaches for R. padi control, the activity of 10 botanical insecticides was evaluated. Results suggested that the toxicity of rotenone and pyrethrins to R. padi were the highest and near to the commonly used chemical insecticides. When exposed to the low-lethal concentrations (LC 10 , LC 30 ) of rotenone or pyrethrins for 24 h, the lifespan and fecundity of adults in F0 generation decreased significantly compared to control. The negative effect could also be observed in the F1 generation, including the decreased average offspring, longevity of adult, and prolonged nymph period. The population parameters in F1 generation of R. padi were also inhibited by exposing to the low-lethal concentrations of rotenone or pyrethrins, including the decreased net reproductive rate, intrinsic rate of natural increase, finite rate of population increase, and gross reproduction rate. Co-toxocity factor results showed that mixtures of rotenone and thiamethoxam, pyrethrins and thiamethoxam showed synergistic effect. Our work suggested that rotenone and pyrethrins showed negative effect on the population growth under low-lethal concentrations. They are suitable for R. padi control as foliar spraying without causing population resurgence.

Chlorfenapyr is a novel broad-spectrum insecticide derived from natural pyrrole derivatives produced by Streptomyces spp. It acts as a pro-insecticide and is metabolically converted to the active metabolite, tralopyril. Chlorfenapyr poisoning is known for its delayed neurological symptoms and high mortality. Unfortunately, information on the toxicokinetics, metabolism and tissue distribution of chlorfenapyr and tralopyril is still lacking. In this study, the metabolic profile, toxicokinetics and tissue distribution of chlorfenapyr and tralopyril after oral administration at a toxic dose in mice were investigated. Twenty metabolites were identified in plasma, urine and feces, which were mainly formed by dealkylation, oxidative dechlorination and reductive dechlorination. Toxicokinetic results showed that chlorfenapyr was rapidly converted to tralopyril after administration, and the in vivo half-life (t1/2), area under the curve (AUC) and peak concentration (Cmax) values of tralopyril were significantly higher than those of chlorfenapyr (P < 0.05). Tissue distribution experiments confirmed that the metabolite tralopyril had a longer half-life, a lower clearance and a wide distribution in different organs and tissues compared to chlorfenapyr. It was also able to cross the blood–brain barrier, suggesting a potential association with brain lesions. In addition, a sensitive and rapid LC–MS/MS analytical method was established for the detection of chlorfenapyr and tralopyril. In conclusion, this study provided valuable metabolic, toxicokinetic and tissue distribution information, contributing to future risk assessment and forensic identification in cases of chlorfenapyr poisoning. We recommend considering the assessment of tralopyril levels, which may be of greater therapeutic importance in the management of chlorfenapyr poisoning.