Phylogenomic analysis of Stylops reveals the evolutionary history of a Holarctic Strepsiptera radiation parasitizing wild bees.

Holarctic Stylops is the largest genus of the enigmatic insect order Strepsiptera, twisted winged parasites. Members of Stylops are obligate endoparasites of Andrena mining bees and exhibit extreme sexual dimorphism typical of Strepsiptera. So far, molecular studies on Stylops have focused on questions on species delimitation. Here, we utilize the power of whole genome sequencing to infer the phylogeny of this morphologically challenging genus from thousands of loci. We use a species tree method, concatenated maximum likelihood analysis and Bayesian analysis with a relaxed clock model to reconstruct the phylogeny of 46 Stylops species, estimate divergence times, evaluate topological consistency across methods and infer the root position. Furthermore, the biogeographical history and coevolutionary patterns with host species are assessed. All methods recovered a well resolved topology with close to all nodes maximally supported and only a handful of minor topological variations. Based on the result, we find that included species can be divided into 12 species groups, seven of them including only Palaearctic species, three Nearctic and two were geographically mixed. We find a strongly supported root position between a clade formed by the spreta, thwaitesi and gwynanae species groups and the remaining species and that the sister group of Stylops is Eurystylops or Eurystylops + Kinzelbachus. Our results indicate that Stylops originated in the Western Palaearctic or Western Palaearctic and Nearctic in the early Neogene or late Paleogene, with four independent dispersal events to the Nearctic. Cophylogenetic analyses indicate that the diversification of Stylops has been shaped by both significant coevolution with the mining bee hosts and host-shifting. The well resolved and strongly supported phylogeny will provide a valuable phylogenetic basis for further studies into the fascinating world of Strepsipterans.

A sodium-dependent trehalose transporter contributes to anhydrobiosis in insect cell line, Pv11.

Pv11 is the only animal cell line that, when preconditioned with a high concentration of trehalose, can be preserved in the dry state at room temperature for more than one year while retaining the ability to resume proliferation. This extreme desiccation tolerance is referred to as anhydrobiosis. Here, we identified a transporter that contributes to the recovery of Pv11 cells from anhydrobiosis. In general, the solute carrier 5 (SLC5)-type secondary active transporters cotransport Na+ and carbohydrates including glucose. The heterologous expression systems showed that the transporter belonging to the SLC5 family, whose expression increases upon rehydration, exhibits Na+-dependent trehalose transport activity. Therefore, we named it STRT1 (sodium-ion trehalose transporter 1). We report an SLC5 family member that transports a naturally occurring disaccharide, such as trehalose. Knockout of the Strt1 gene significantly reduced the viability of Pv11 cells upon rehydration after desiccation. During rehydration, when intracellular trehalose is no longer needed, Strt1-knockout cells released the disaccharide more slowly than the parental cell line. During rehydration, Pv11 cells became roughly spherical due to osmotic pressure changes, but then returned to their original spindle shape after about 30 min. Strt1-knockout cells, however, required about 50 min to adopt their normal morphology. STRT1 probably regulates intracellular osmolality by releasing unwanted intracellular trehalose with Na+, thereby facilitating the recovery of normal cell morphology during rehydration. STRT1 likely improves the viability of dried Pv11 cells by rapidly alleviating the significant physical stresses that arise during rehydration.

Mechanoecology: biomechanical aspects of insect-plant interactions.

Plants and herbivorous insects as well as their natural enemies, such as predatory and parasitoid insects, are united by intricate relationships. During the long period of co-evolution with insects, plants developed a wide diversity of features to defence against herbivores and to attract pollinators and herbivores' natural enemies. The chemical basis of insect-plant interactions is established and many examples are studied, where feeding and oviposition site selection of phytophagous insects are dependent on the plant's secondary chemistry. However, often overlooked mechanical interactions between insects and plants can be rather crucial. In the context of mechanoecology, the evolution of plant surfaces and insect adhesive pads is an interesting example of competition between insect attachment systems and plant anti-attachment surfaces. The present review is focused on mechanical insect-plant interactions of some important pest species, such as the polyphagous Southern Green Stinkbug Nezara viridula and two frugivorous pest species, the polyphagous Mediterranean fruit fly Ceratitis capitata and the monophagous olive fruit fly Bactrocera oleae. Their ability to attach to plant surfaces characterised by different features such as waxes and trichomes is discussed. Some attention is paid also to Coccinellidae, whose interaction with plant leaf surfaces is substantial across all developmental stages in both phytophagous and predatory species that feed on herbivorous insects. Finally, the role of different kinds of anti-adhesive nanomaterials is discussed. They can reduce the attachment ability of insect pests to natural and artificial surfaces, potentially representing environmental friendly alternative methods to reduce insect pest impact in agriculture.

Complexity of responses to ionizing radiation in plants, and the impact on interacting biotic factors.

In nature, plants are simultaneously exposed to different abiotic (e.g., heat, drought, and salinity) and biotic (e.g., bacteria, fungi, and insects) stresses. Climate change and anthropogenic pressure are expected to intensify the frequency of stress factors. Although plants are well equipped with unique and common defense systems protecting against stressors, they may compromise their growth and development for survival in such challenging environments. Ionizing radiation is a peculiar stress factor capable of causing clustered damage. Radionuclides are both naturally present on the planet and produced by human activities. Natural and artificial radioactivity affects plants on molecular, biochemical, cellular, physiological, populational, and transgenerational levels. Moreover, the fitness of pests, pathogens, and symbionts is concomitantly challenged in radiologically contaminated areas. Plant responses to artificial acute ionizing radiation exposure and laboratory-simulated or field chronic exposure are often discordant. Acute or chronic ionizing radiation exposure may occasionally prime the defense system of plants to better tolerate the biotic stress or could often exhaust their metabolic reserves, making plants more susceptible to pests and pathogens. Currently, these alternatives are only marginally explored. Our review summarizes the available literature on the responses of host plants, biotic factors, and their interaction to ionizing radiation exposure. Such systematic analysis contributes to improved risk assessment in radiologically contaminated areas.

The first A-to-I RNA editome of hemipteran species Coridius chinensis reveals overrepresented recoding and prevalent intron editing in early-diverging insects.

BACKGROUND: Metazoan adenosine-to-inosine (A-to-I) RNA editing resembles A-to-G mutation and increases proteomic diversity in a temporal-spatial manner, allowing organisms adapting to changeable environment. The RNA editomes in many major animal clades remain unexplored, hampering the understanding on the evolution and adaptation of this essential post-transcriptional modification. METHODS: We assembled the chromosome-level genome of Coridius chinensis belonging to Hemiptera, the fifth largest insect order where RNA editing has not been studied yet. We generated ten head RNA-Seq libraries with DNA-Seq from the matched individuals. RESULTS: We identified thousands of high-confidence RNA editing sites in C. chinensis. Overrepresentation of nonsynonymous editing was observed, but conserved recoding across different orders was very rare. Under cold stress, the global editing efficiency was down-regulated and the general transcriptional processes were shut down. Nevertheless, we found an interesting site with "conserved editing but non-conserved recoding" in potassium channel Shab which was significantly up-regulated in cold, serving as a candidate functional site in response to temperature stress. CONCLUSIONS: RNA editing in C. chinensis largely recodes the proteome. The first RNA editome in Hemiptera indicates independent origin of beneficial recoding during insect evolution, which advances our understanding on the evolution, conservation, and adaptation of RNA editing.

The pharyngeal taste organ of a blood-feeding insect functions in food recognition.

BACKGROUND: Obligate blood-feeding insects obtain the nutrients and water necessary to ensure survival from the vertebrate blood. The internal taste sensilla, situated in the pharynx, evaluate the suitability of the ingested food. Here, through multiple approaches, we characterized the pharyngeal organ (PO) of the hematophagous kissing bug Rhodnius prolixus to determine its role in food assessment. The PO, located antero-dorsally in the pharynx, comprises eight taste sensilla that become bathed with the incoming blood. RESULTS: We showed that these taste sensilla house gustatory receptor neurons projecting their axons through the labral nerves to reach the subesophageal zone in the brain. We found that these neurons are electrically activated by relevant appetitive and aversive gustatory stimuli such as NaCl, ATP, and caffeine. Using RNA-Seq, we examined the expression of sensory-related gene families in the PO. We identified gustatory receptors, ionotropic receptors, transient receptor potential channels, pickpocket channels, opsins, takeouts, neuropeptide precursors, neuropeptide receptors, and biogenic amine receptors. RNA interference assays demonstrated that the salt-related pickpocket channel Rproppk014276 is required during feeding of an appetitive solution of NaCl and ATP. CONCLUSIONS: We provide evidence of the role of the pharyngeal organ in food evaluation. This work shows a comprehensive characterization of a pharyngeal taste organ in a hematophagous insect.

Edible insects as a source of biopeptides and their role in immunonutrition.

Many edible insect species are attracting the attention of the food industry and consumers in Western societies due to their high content and quality of protein, and consequently, the potential to be used as a more environmentally friendly dietary source could be beneficial for humans. On the other hand, prevention of inflammatory diseases using nutritional interventions is currently being proposed as a sustainable and cost-effective strategy to improve people's health. In this regard, finding bioactive compounds such as peptides with anti-inflammatory properties from sustainable sources (e.g., edible insects) is one area of particular interest, which might have a relevant role in immunonutrition. This review aims to summarize the recent literature on the discovery of immunomodulatory peptides through in vitro studies from edible insects, as well as to describe cell-based assays aiming to prove their bioactivity. On top of that, in vivo studies (i.e., animal and human), although scarce, have been mentioned in relation to the topic. In addition, the challenges and future perspectives related to edible-insect peptides and their role in immunonutrition are discussed. The amount of literature aiming to demonstrate the potential immunomodulatory activity of edible-insect peptides is scarce but promising. Different approaches have been employed, especially cell assays and animal studies employing insect meal as supplementation in the diet. Insects such as Tenebrio molitor or Gryllodes sigillatus are some of the most studied and have demonstrated to contain bioactive peptides. Further investigations, mostly with humans, are needed in order to clearly state that peptides from edible insects may contribute to the modulation of the immune system.

A comprehensive sampling of mitogenomes shows the utility to infer phylogeny of termites (Blattodea: Termitoidae).

The mitogenome sequence data have been widely used in inferring the phylogeny of insects. In this study, we determined the complete mitogenome for Macrotermes sp. (Termitidae, Macrotermitinae) using next-generation sequencing. Macrotermes sp. possesses a typical insect mitogenome, displaying an identical gene order and gene content to other existing termite mitogenomes. We present the first prediction of the secondary structure of ribosomal RNA genes in termites. The rRNA secondary structures of Macrotermes sp. exhibit similarities to closely related insects and also feature distinctive characteristics in their helical structures. Together with 321 published mitogenomes of termites as ingroups and 8 cockroach mitogenomes as outgroups, we compiled the most comprehensive mitogenome sequence matrix for Termitoidae to date. Phylogenetic analyses were conducted using datasets employing different data coding strategies and various inference methods. Robust relationships were recovered at the family or subfamily level, demonstrating the utility of comprehensive mitogenome sampling in resolving termite phylogenies. The results supported the monophyly of Termitoidae, and consistent relationships within this group were observed across different analyses. Mastotermitidae was consistently recovered as the sister group to all other termite families. The families Hodotermitidae, Stolotermitidae, and Archotermopsidae formed the second diverging clade, followed by the Kalotermitidae. The Neoisoptera was consistently supported with strong node support, with Stylotermitidae being sister to the remaining families. Rhinotermitidae was found to be non-monophyletic, and Serritermitidae nested within the basal clades of Rhinotermitidae and was sister to Psammotermitinae. Overall, our phylogenetic results are largely consistent with earlier mitogenome studies.

Insect galls from the Botanical Garden of the Museu Nacional (Rio de Janeiro, RJ, Brazil).

The Botanical Garden of the Museu Nacional/Universidade Federal do Rio de Janeiro (Rio de Janeiro, RJ, Brazil) was investigated monthly from October, 2017 to December, 2019 in a total of 27 collections, each lasting four hours, following the methodology of random walking. Vegetative and reproductive organs of herbs, bushes and trees (up to 2 m high) were examined by two people. Voucher material was deposited in the Entomological Collection of the Museu Nacional (MNRJ)/Universidade Federal do Rio de Janeiro. We found 13 insect gall morphotypes in nine host plant species of four families. All host plants are native of Brazil, except Ficus microcarpa L.f. (Moraceae), which is naturalized. Myrtaceae and Moraceae were the plant families with the greatest richness of gall morphotypes. Eugenia L. (Myrtaceae) and Ficus L. (Moraceae) were the plant genera with the highest number of gall morphotypes. In several inventories in the Atlantic forest, Myrtaceae and Eugenia stand out for harboring a great variety of galls, while Moraceae and Ficus were never stood out for this reason. Most plant species mentioned in the present study were already known as hosts of gall-inducing insects in Brazil. However, for the first time, insect galls are reported on Ficus crocata (Miq.) Miq. (Moraceae). We found two new morphotypes on Eugenia florida DC. (Myrtaceae). Leaves, stems and buds were the galled organs. Cecidomyiidae were the most frequent inducers. Galls of Thysanoptera were also found. Inquilines were observed in leaf galls on Eugenia florida. They promoted differences in gall morphology and killed the gall-inducing larva.

Pri peptides temporally coordinate transcriptional programs during epidermal differentiation.

To achieve a highly differentiated state, cells undergo multiple transcriptional processes whose coordination and timing are not well understood. In Drosophila embryonic epidermal cells, polished-rice (Pri) smORF peptides act as temporal mediators of ecdysone to activate a transcriptional program leading to cell shape remodeling. Here, we show that the ecdysone/Pri axis concomitantly represses the transcription of a large subset of cuticle genes to ensure proper differentiation of the insect exoskeleton. The repression relies on the transcription factor Ken and persists for several days throughout early larval stages, during which a soft cuticle allows larval crawling. The onset of these cuticle genes normally awaits the end of larval stages when the rigid pupal case assembles, and their premature expression triggers abnormal sclerotization of the larval cuticle. These results uncovered a temporal switch to set up distinct structures of cuticles adapted to the animal lifestyle and which might be involved in the evolutionary history of insects.

Odours of caterpillar-infested trees increase testosterone concentrations in male great tits.

Trees release Herbivore-Induced Plant Volatiles (HIPVs) into the air in response to damage inflicted by insects. It is known that songbirds use those compounds to locate their prey, but more recently the idea emerged that songbirds could also use those odours as cues in their reproductive decisions, as early spring HIPVs may contain information about the seasonal timing and abundance of insects. We exposed pre-breeding great tits (Parus major) to the odours of caterpillar-infested trees under controlled conditions, and monitored reproduction (timing of egg laying, number of eggs, egg size) and two of its main hormonal drivers (testosterone and 17ß-estradiol in males and females, respectively). We found that females exposed to HIPVs did not advance their laying dates, nor laid larger clutches, or larger eggs compared to control females. 17ß-estradiol concentrations in females were also similar between experimental and control birds. However, males exposed to HIPVs had higher testosterone concentrations during the egg-laying period. Our study supports the hypothesis that insectivorous songbirds are able to detect minute amounts of plant odours. The sole manipulation of plant scents was not sufficient to lure females into a higher reproductive investment, but males increased their reproductive effort in response to a novel source of information for seasonal breeding birds.

Impact of a glyphosate-based herbicide on the longevity, fertility, and transgenerational effects on Chrysopa pallens (Rambur) (Neuroptera: Chrysopidae).

Glyphosate-based herbicides (GBHs) are common herbicide formulations used in the field and are increasingly used worldwide with the widespread cultivation of herbicide-tolerant genetically modified crops. As a result, the risk of arthropod exposure to GBH is increasing rapidly. Chrysopa pallens (Rambur) (Neuroptera: Chrysopidae) is a common predatory natural enemy in agroecosystems, which is exposed to GBH (Roundup®) while preying on pests. To identify and characterize the potential effects of GBH on C. pallens, the life tables of C. pallens larvae and adults fed with GBH were constructed. Moreover, the effects of GBH treatment on the expression of genes involved in insulin signalling in adults were analyzed using qRT-PCR. The results showed that GBH treatment altered the pupal period and preadult stage of C. pallens larvae. However, it did no effect on longevity, fecundity, and population parameters and two insulin receptor genes (InR1, InR2), a serine/threonine kinase (Akt), an extracellular-signal-regulated kinase (erk), and vitellogenin (Vg1) expression of C. pallens. Adults feeding on GBH significantly altered development, longevity, and differences in the mean generation time of the F0 generation. However, GBH feeding only minimally influenced the growth and population parameters of the F1 generation. In addition, InR1, InR2, erk, and Vg1 expression in the F0 generation were downregulated on the fifth day of feeding on GBH. Furthermore, the expression levels of InR1, InR2, Akt, erk, and Vg1 in C. pallens decreased with the increase of GBH concentration, although the expression levels returned to control levels on the tenth day. Overall, the consumption of the GBH by larvae and adults of C. pallens had minimal effect on the growth and population parameters of C. pallens. The findings of this study can provide a reference for elucidating the environmental risks of GBH, guiding the optimal use of glyphosate in agricultural practices in the future.

A biodynamic model predicting copper and cadmium bioaccumulation in caddisflies: Linkages between field studies and laboratory exposures.

Hydropsyche and Arctopsyche are filter-feeding caddisflies (Order: Trichoptera; Family: Hydropsychidae) that are commonly used to monitor metal exposures in rivers. While tissue residue concentrations provide important bioaccumulation data regarding metal bioavailability, they do not provide information regarding the mechanisms of uptake and loss, or exposure history. This study examined the physiological processes that control Cu and Cd uptake and loss using a biokinetic bioaccumulation model. Larvae of each taxon were experimentally exposed to either water or food enriched with stable isotopes (65Cu and 106Cd). Dissolved Cu uptake (ku) was similar between species (2.6-3.4 L-1g 1d-1), but Cd uptake was 3-fold higher in Hydropsyche than Arctopsyche (1.85 L-1g 1d-1 and 0.60 L-1g 1d-1, respectively). Cu and Cd efflux rates (ke) were relatively fast (0.14 d-1-0.24 d-1) in both species, and may explain, in part, their metal tolerance to mine-impacted rivers. Food ingestion rates (IR), assimilation efficiency (AE) of 65Cu and 106Cd from laboratory diets were also derived and used in a biodynamic model to quantify the relative contribution of dissolved and dietary exposure routes. Results from the biodynamic model were compared to tissue concentrations observed in a long-term field study and indicated that because dissolved Cu and Cd exposures accounted for less than 20% of body concentrations of either taxon, dietary exposure was the predominant metal pathway. An estimation of exposure history was determined using the model to predict steady state concentrations. Under constant exposure conditions (dissolved plus diet), steady state concentrations were reached in less than 30 days, an outcome largely influenced by rapid efflux (ke).

[Production of adeno-associated virus in insect cells using multiple gene deleted baculovirus].

Adeno-associated virus (AAV) is one of the most frequently used viral vectors in the field of gene therapy. However, the industrial production of AAV is facing key bottlenecks such as low yield and high-cost. The aim of this study was to establish a technology system for production of AAV in the double virus infected insects by using multiple-gene deleted baculovirus. First, a multiple gene deleted baculovirus for AAV production was constructed, and the baculovirus titer and its effect on infected cells was examined. Subsequently, the insect cells were co-infected with the double baculovirus and the infection conditions were optimized. At the final stage, we performed AAV production based on optimized conditions, and evaluated relevant parameters including production titer and quality. The results showed that the titer of AAV produced in the multiple gene deleted baculovirus was not different from that of the wild type, but the rate of cell death was significantly slower upon infection. Using the double virus route for optimized production of AAV, the genome titers were 1.63×1011 VG/mL for Bac4.0-1 and 1.02×1011 VG/mL for Bac5.0-2, which were elevated 240% and 110%, respectively, compared with that of the wild-type. Electron microscopy observations revealed that all three groups exhibited normal AAV viral morphology and they showed similar transduction activity. Taken together, we developed an AAV production system based on the infection of insect cells using multiple-gene deleted baculovirus, which significantly improved the virus yield and showed application potential.

Single Deletion Unmasks Hidden Anti-Gram-Negative Bacterial Activity of an Insect Defensin-Derived Peptide.

Insect defensins are a large family of antimicrobial peptides primarily active against Gram-positive bacteria. Here, we explore their hidden anti-Gram-negative bacterial potential via a nature-guided strategy inspired by natural deletion variants of Drosophila defensins. Referring to these variants, we deleted the equivalent region of an insect defensin with the first cysteine-containing N-terminus, and the last three cysteine-containing C-terminal regions remained. This 15-mer peptide exhibits low solubility and specifically targets Gram-positive bacteria. Further deletion of alanine-9 remarkably improves its solubility, unmasks its hidden anti-Gram-negative bacterial activity, and alters its states in different environments. Intriguingly, compared with the oxidized form, the 14-mer reduced peptide shows increased activity on Gram-positive and Gram-negative bacteria through a membrane-disruptive mechanism. The broad-spectrum activity and tolerance to high-salt environments and human serum, together with no toxicity to mammalian or human cells, make it a promising candidate for the design of new peptide antibiotics against Gram-negative bacterial infections.

Insect neurobiology: Oviposition crowd control.

A new study examines how Helicoverpa armigera females detect chemicals released by conspecific eggs in order to avoid laying more eggs on the same substrate. This work opens new avenues for basic research inquiries and offers a potential strategy for controlling insect pests.

The angiosperm radiation played a dual role in the diversification of insects and insect pollinators.

Interactions with angiosperms have been hypothesised to play a crucial role in driving diversification among insects, with a particular emphasis on pollinator insects. However, support for coevolutionary diversification in insect-plant interactions is weak. Macroevolutionary studies of insect and plant diversities support the hypothesis that angiosperms diversified after a peak in insect diversity in the Early Cretaceous. Here, we used the family-level fossil record of insects as a whole, and insect pollinator families in particular, to estimate diversification rates and the role of angiosperms on insect macroevolutionary history using a Bayesian process-based approach. We found that angiosperms played a dual role that changed through time, mitigating insect extinction in the Cretaceous and promoting insect origination in the Cenozoic, which is also recovered for insect pollinator families only. Although insects pollinated gymnosperms before the angiosperm radiation, a radiation of new pollinator lineages began as angiosperm lineages increased, particularly significant after 50 Ma. We also found that global temperature, increases in insect diversity, and spore plants were strongly correlated with origination and extinction rates, suggesting that multiple drivers influenced insect diversification and arguing for the investigation of different explanatory variables in further studies.

Single domain von Willebrand factor type C "cytokines" and the regulation of the stress/immune response in insects.

The single domain von Willebrand factor type C (SVWC) appears in small secreted peptides that are arthropod-specific and are produced following environmental stress or pathogen exposure. Most research has focused on proteins with SVWC domain that are induced after virus infection and are hypothesized to function as "cytokines" to regulate the innate immune response. The expansion of SVWC genes in insect species indicates that many other functions remain to be discovered. Research in shrimp has elucidated the adaptability of Vago-like peptides in the innate immune response against bacteria, fungi and viruses after activation by Jak-STAT and/or Toll/Imd pathways in which they can act as pathogen-recognition receptors or cytokine-like signaling molecules. SVWC factors also appear in scorpion venoms and tick saliva, underlining their versatility to acquire new functions. This review discusses the discovery and function of SVWC peptides from insects to crustaceans and chelicerates and reveals the enormous gaps in knowledge that remain to be filled to understand this enigmatic group of secreted peptides.

Ecological Implications on Aquatic Food Webs Due to Effects of Pesticides on Invertebrate Predators in a Neotropical Region.

Predation presents specific behavioral characteristics for each species, and the interaction between prey and predator influences the structuring of the food web. Concerning insects, predation can be affected in different ways, such as exposure to chemical stressors, e.g., pesticides. Therefore, analyses were carried out of the effects of exposure to insecticide fipronil and the herbicide 2,4-D on predation, parameters of food selectivity, and the swimming behavior of two neotropical predatory aquatic insects of the families Belostomatidae (giant water bugs) and larvae of Libellulidae (dragonfly). These predatory insects were exposed for 24 h to a commercial formulation of the chlorophenoxy herbicide, 2,4-D at nominal concentrations of 200, 300, 700, and 1400 µg L-1, and to a commercial formulation of the phenylpyrazole insecticide, fipronil at nominal concentrations of 10, 70, 140, and 250 µg L-1. In a control treatment, the insects were placed in clean, unspiked water. At the end of the exposure, the maximum swimming speed of the predators was evaluated. Afterward, the predators were placed in clean water in a shared environment for 24 h with several prey species, including the cladoceran Ceriodaphnia silvestrii, larvae of the insect Chironomus sancticaroli, the amphipod Hyalella meinerti, the ostracod Strandesia trispinosa, and the oligochaete Allonais inaequalis for 24 h. After this period, the consumed prey was counted. The results reveal that predators from both families changed prey consumption compared with organisms from the control treatment, marked by a decrease after exposure to fipronil and an increase in consumption caused by 2,4-D. In addition, there were changes in the food preferences of both predators, especially when exposed to the insecticide. Exposure to fipronil decreased the swimming speed of Belostomatidae individuals, possibly due to its neurotoxic effect. Exposure to the insecticide and the herbicide altered prey intake by predators, which could negatively influence the complex prey-predator relationship and the functioning of aquatic ecosystems in contaminated areas.

Assessment of the impacts of GABA and AChE targeting pesticides on freshwater invertebrate family richness in English Rivers.

Globally, riverine system biodiversity is threatened by a range of stressors, spanning pollution, sedimentation, alterations to water flow, and climate change. Pesticides have been associated with population level impacts on freshwater invertebrates for acute high-level exposures, but far less is known about the chronic impact of episodic exposure to specific classes of pesticides or their mixtures. Here we employed the use of the UK Environment Agency's monitoring datasets over 40 years (covering years 1980 to 2019) to assess the impacts of AChE (acetylcholinesterase) and GABA (gamma-aminobutyric acid) receptor targeting pesticides on invertebrate family richness at English river sites. Concentrations of AChE and GABA pesticides toxic to freshwater invertebrates occurred (measured) across 18 of the 66 river sites assessed. For one of the three river sites (all found in the Midlands region of England) where data recorded over the past 40 years were sufficient for robust modelling studies, both AChE and GABA pesticides associated with invertebrate family richness. Here, where AChE total pesticide concentrations were classified as high, 46 of 64 invertebrate families were absent, and where GABA total pesticide concentration were classified as high, 16 of 64 invertebrate families were absent. Using a combination of field evidence and laboratory toxicity thresholds for population relevant endpoints we identify families of invertebrates most at risk in the selected English rivers to AChE and GABA pesticides. We, furthermore, provide strong evidence that the absence of the invertebrate family Polycentropodidae (caddisfly) from one field site is due to exposure effects to AChE pesticides.