Effects of the pesticide dimethoate on a non-target generalist carabid,Pterostichus melas italicus(Dejean, 1828) (Coleoptera: Carabidae)

Overhauling the ecotoxicological impact of synthetic pesticides using plants' natural products: a focus on Zanthoxylum metabolites

The reduction in agricultural production due to the negative impact of insects and weeds, as well as the health and economic burden associated with vector-borne diseases, has promoted the wide use of chemicals that control these "enemies." However, the use of these synthetic chemicals has been recognized to elicit negative impacts on the environment as well as the health and wellbeing of man. In this study, we presented an overview of recent updates on the environmental and health impacts of synthetic pesticides against agro-pest and disease vectors while exhaustive reviewing the potentials of natural plant products from Zanthoxylum species (Rutaceae) as sustainable alternatives. This study is expected to spur further research on exploiting these plants and their chemicals as safe and effective pesticide entities to minimize the impact of their chemical and synthetic counterparts on health and the environment.

Dietary, locomotory, and metabolic reactions of Abax parallelus (Coleoptera, Carabidae) to acute thiamethoxam intoxication

Carabids (Coleoptera: Carabidae) are abundant predators in ecosystems and serve as pest biocontrol in agroecosystems and forestry. Here we test the impact of thiamethoxam, among the most used neonicotinoids on the consumption rate, locomotion, metabolomics, and oxidative stress level measuring superoxide dismutase (SOD) activity in a predatory carabid, Abax parallelus (Duftschmid, 1812), after acute exposure in the laboratory trials, to get additional data that might link the use of pesticides and predation efficiency. Beetles were exposed to increasing concentrations of thiamethoxam by dipping method, and left to feed overnight prior to the assays. The results showed that individuals treated with higher concentrations of thiamethoxam (20 and 40 mg/L) consumed significantly less food per body weight and had a higher share of intoxicated and moribund individuals. The mass of consumed food per beetle body weight and observed locomotion did not differ significantly between control and groups treated with lower concentrations of thiamethoxam. There are significant differences in concentrations of some metabolites between treated and control individuals, primary in succinate and d-glucose, indicating a disruption in energy production. On the other hand, there is no statistically significant differences in SOD activity among the groups. To conclude, acute exposure to thiamethoxam can result in negative sub-lethal effects in predatory activity and energy budget, while the effects of long-term exposure to lower doses require further research, as well as field assessment on the predation efficiency after pesticide application.

The Gut Bacterial Community of Chlaenius pallipes (Coleoptera: Carabidae) Associates with Their Habitat and Morphology

We investigated whether the gut bacterial community of Chlaenius pallipes could represent the health conditions of individuals or populations based on where these beetles inhabit. Considering the ecological traits of the species, the gut bacterial communities of carabid populations inhabiting stable or unstable habitats were compared. Food resource quality (δ¹⁵N) and morphological shape, especially body and wing size, may be significant factors that directly or indirectly affect the gut bacterial community of carabid beetles. Firmicutes (51.7%) and Proteobacteria (36.3%) were the predominant phyla in the gut bacterial community of C. pallipes. A significant difference in the gut bacterial community structure was observed between organisms inhabiting unstable and stable habitats in this study. Wing size, as estimated by centroid size, was correlated with differences in the gut bacterial community composition of the species. Even if a factor is not strong enough to determine the survival of carabid beetles, the composition of the gut bacterial community can change. We found that although each individual has a large variation in the gut bacterial community composition, the gut bacterial community can be used to evaluate the condition of each habitat through consistent investigation. Habitat assessment based on changes in the number of carabid beetle species and their composition requires relatively long-term research; however, the gut bacterial community of carabid beetles can help identify short-term environmental changes.

Rare species of Carabidae and Cicindelidae in Dnipropetrovsk Region, Ukraine

Dnipropetrovsk Region is situated in the steppe zone of Ukraine, in conditions of insufficient moisture. Forest vegetation covers only 5.1% of the region. Over 80% of the region’s area is used for agricultural purposes. A total of 281 species of ground beetles is known for the region, of which this article gives the data on biology and distribution of 82 species that need protection: Cephalota atrata, C. besseri, C. elegans, Cicindela maritima, C. soluta, Cylindera arenaria, Leistus terminatus, Notiophilus rufipes, Calosoma sycophanta, C. denticolle, C. investigator, Carabus stscheglowi, C. clathratus, C. excellens, C. hungaricus, C. besseri, C. estreicheri, C. sibiricus, Blethisa multipunctata, Elaphrus uliginosus, Scarites terricola, Dyschirius chalceus, Dyschirius obscurus, Blemus discus, Epaphius secalis, Bembidion ephippium, B. aspericolle, Pogonus cumanus, Pogonistes convexicollis, Patrobus atrorufus, Stomis pumicatus, Pedius inquinatus, Pterostichus chamaeleon, P. elongatus, P. macer, P. melas, Taphoxenus gigas, Laemostenus terricola, Agonum impressum, A. marginatum, A. monachum, A. sexpunctatum, A. viridicupreum, Olisthopus sturmii, Synuchus vivalis, Amara chaudoiri, A. crenata, A. equestris, A. fulva, A. sabulosa, Curtonotus convexiusсulus, Anisodastylus poeciloides, Diachromus germanus, Acupalpus interstitialis, A. suturalis, Stenolophus discophorus, Daptus vittatus, Harpalus cephalotes, H. dispar, H. hirtipes, Н. laeviceps, H. luteicornis, H. melancholicus, H. steveni, H. subcylindricus, Microderes brachypus, Ophonus diffinis, Dixus eremita, Panagaeus bipustulatus, Callistus lunatus, Dinodes decipiens, Chlaenius alutaceus, Ch. festivus, Licinus cassideus, Badister dorsiger, Masoreus wetterhalli, Lebia humeralis, Demetrias imperialis, Cymindis axillaris, Polystichus connexus, Brachinus ejaculans, B. hamatus, Mastax thermarum. To formalize the data on each species, the article provides characteristics of its ecological niche: thermal preferendum, hygro-preferendum, biotopical characteristic, biogeohorizon, trophic preferences, practical significance and protection measures. The main factors of decline in diversity of the fauna of ground beetles in Dnipropetrovsk Region are arable farming, chemical treatment of agricultural land, unregulated cattle grazing, recreational loading, large scale construction in floodplain areas.

Exploring Compound Eyes in Adults of Four Coleopteran Species Using Synchrotron X-ray Phase-Contrast Microtomography (SR-PhC Micro-CT)

Compound eyes in insects are primary visual receptors of surrounding environments. They show considerable design variations, from the apposition vision of most day-active species to the superposition vision of nocturnal insects, that sacrifice resolution to increase sensitivity and are able to overcome the challenges of vision during lightless hours or in dim habitats. In this study, Synchrotron radiation X-ray phase-contrast microtomography was used to describe the eye structure of four coleopteran species, showing species-specific habitat demands and different feeding habits, namely the saproxylic Clinidium canaliculatum (Costa, 1839) (Rhysodidae), the omnivorous Tenebrio molitor (Linnaeus, 1758) and Tribolium castaneum (Herbest, 1797) (Tenebrionidae), and the generalist predator Pterostichus melas italicus (Dejean, 1828) (Carabidae). Virtual sections and 3D volume renderings of the heads were performed to evaluate the application and limitations of this technique for studying the internal dioptrical and sensorial parts of eyes, and to avoid time-consuming methods such as ultrastructural analyses and classic histology. Morphological parameters such as the area of the corneal facet lens and cornea, interocular distance, facet density and corneal lens thickness were measured, and differences among the studied species were discussed concerning the differences in lifestyle and habitat preferences making different demands on the visual system. Our imaging results provide, for the first time, morphological descriptions of the compound eyes in these species, supplementing their ecological and behavioural traits.

Synchrotron X-ray phase contrast micro tomography to explore the morphology of abdominal organs in Pterostichus melas italicus Dejean, 1828 (Coleoptera, Carabidae)

Micro-computer tomography imaging is a fast and non-destructive data acquisition technique which can replace or complement the traditional investigation methodologies used in entomology to study morphology. In this paper, Synchrotron Radiation X-ray Phase-Contrast micro tomography (SR-PhC micro-CT) was combined with histology and scanning electron microscopy (SEM) observations to describe the abdominal organs of Pterostichus melas italicus Dejean, 1828 (Coleoptera, Carabidae). This species was used as a representative model because of its ecological role as a generalist predator in agroecosystems. SR-PhC micro-CT allowed us to identify in situ abdominal structures including dorsal vessel, digestive tract with Malpighian tubules, male reproductive system, ganglia, fat bodies, pygidial glands, muscles and tracheae. The histology was performed to define the tissue organization of the digestive and reproductive systems. SR-PhC micro-CT and 3D rendering provided more accurate information on shape and size of organs than histological and SEM analyses, respectively. The finding of this study was to describe the anatomy and histology of organs involved in crucial life history traits, such as reproduction, nutrition and excretion. High quality images and the supplementary video represent a significant advance in knowledge of the carabid anatomy and are a baseline for future research.

Fluctuating Asymmetry as a Method of Assessing Environmental Stress in Two Predatory Carabid Species within Mediterranean Agroecosystems

Fluctuating asymmetry (FA) is used in assessing the effect of environmental stress on the development stability of individuals by measuring small random deviations from perfect bilateral symmetry. Here, we checked for FA on two predatory carabid beetles, Pterostichus melas and Poecilus koyi, in order to evaluate species response to agricultural practices within Mediterranean agroecosystems, as well as FA as a method. The samples were collected in vineyards and olive groves, both under integrated pest management (IPM) and ecological pest management (EPM), and in pristine habitats in the Mediterranean region of Croatia. Geometric morphometrics (GMMs) were used to analyze the pronotum and abdomen shape variations and left–right asymmetries of each population. In respect to the FA measurements, analyzed species responded differently, with P. koyi displaying a lower intensity of FA than P. melas. On the other hand, P. melas beetles from vineyards showed a higher intensity of FA compared with populations from pristine habitats and olive groves. Accordingly, FA pointed out olive groves as potentially less adverse habitats to predatory carabids, keeping in mind the different levels of asymmetry between the two species. Our study singled out P.melas as a more suitable species for further research, in the effect that different agricultural practices can have their impact on non-target invertebrates analyzed by measuring the FA.

Connected Carabids: Network Interactions and Their Impact on Biocontrol by Carabid Beetles

Carabid beetles can greatly contribute to biocontrol in agroecosystems, reducing both insect pests and weed seeds. However, insect foraging and feeding behavior can be highly dependent on the interaction network and spatial structure of the environment, which can make their biocontrol contributions variable. In the present article, we explore how the interaction network of carabids can affect their behavior and how spatial vegetation structure and specific agronomy practices can, in turn, affect the strength of interactions in their network. We suggest that research on carabid biocontrol should move toward an approach in which the network of interactions among pests, carabids, and other organisms within its spatial structure is evaluated, with equal focus on direct and indirect interactions, and provide examples of tools to do so. Overall, we believe this approach will improve our knowledge of carabid networks, help to elucidate the underlying mechanisms of biocontrol, and lay the foundation for future biocontrol strategies.

An exploratory study of energy reserves and biometry as potential tools for assessing the effects of pest management strategies on the earwig, Forficula auricularia L

Apple orchards are heavily treated crops and some sprayed insecticides are recognized to have toxic effects on non-target arthropods. Earwigs are important natural enemies in pip-fruit orchards and contribute to the biological control of aphids. In addition, due to their ease of capture and identification, they are an interesting potential bioindicator of the possible detrimental effects of different orchard management strategies. In this study, we measured the energy reserves and some morphological traits of Forficula auricularia L. sampled in apple orchards under management strategies (organic versus integrated pest management (IPM)). We observed a significant decrease in mass (22 to 27%), inter-eye width (3%), and prothorax width (2 to 5%) in earwigs from IPM compared to organic orchards. Energy body reserves also confirmed these results with a significant decrease of 48% in glycogen and 25 to 42% in lipid content in earwigs from IPM compared to organic orchards. However, the protein content was approximately 70% higher in earwigs from IPM than in organic orchards. Earwigs sampled in IPM orchards may adapt to minimize the adverse toxic effects of pesticide treatments using a large number of strategies, which are reflected in changes to their energy reserves. These strategies could, in turn, influence the population dynamics of natural enemies and impair their role in the biological control of pests in apple orchards.

Behavioural effects of the neonicotinoid insecticide thiamethoxam on the predatory insect Platynus assimilis

Little information is available regarding sublethal effects of neonicotinoids on insect predators, many of which perform important roles in ecosystem functioning and biocontrol. In this study, dose-dependent sublethal effects of a dietary administered neonicotinoid insecticide thiamethoxam on two basic behaviours, locomotion and feeding, were quantified in the carabid Platynus assimilis (Coleoptera, Carabidae) using automated video-tracking and weighing of consumed food, respectively. Acute toxicity tests showed that, when orally administered, the LD₅₀ of thiamethoxam for P. assimilis beetles was 114.5 ng/g. Thiamethoxam at 108.1 ng/g caused a short-term locomotor hyperactivity within several hours of treatment. Next day after exposure to the insecticide, all the beetles were in a state of locomotor hypoactivity independent of the administered dose ranging from 1.1 to 108.1 ng/g. Reduction in clean food consumption rate (CFCR) is another altered behavioural endpoint of poisoned insect predators as first demonstrated in this study. On the first day of thiamethoxam administration, a remarkable reduction in feeding only occurred in beetles treated at 108.1 ng/g but on the next day, this negative effect appeared even at doses ten to a hundred-fold lower. Recovery from locomotion abnormalities and reduced feeding took several days. Both locomotor activity and CFCR are sensitive and valuable ecotoxicological biomarkers of carabids which should be taken into account in Integrated Pest Management programs where optimal combination of reduced insecticide use and biological control by predatory insects is crucial to achieve best results.

Impact of agrochemicals on non-target species: Calathus fuscipes Goeze 1777 (Coleoptera: Carabidae) as model

Carabid beetles are important in the biological control of arable crop pests. Agricultural practices can produce over time a delayed toxic effect at the organismal and population levels and can compromise the survival on these species. In this research, we quantified the cumulative sublethal effect on body size, Malpighian tubules and immune responses in Calathus fuscipes adults living in the potato field and exposed to lambda-cyhalothrin and cymoxanil-based commercial formulates. Reductions of morphological parameters such as body, pronotum and elytron in both males and females from the potato field indicated that the pre-imaginal stages (larvae and pupae) suffer the sublethal effects of exposure to the larvicide control action of lambda-cyhalothrin. Ultrastructural alterations recorded in Malpighian tubules at the level of plasma membrane, mitochondria and nucleus indicated the reduction of the detoxification capability. The basal phenoloxidase and lysozyme-like enzyme activities have measured as markers of immune competence. Spectrophometric analyses showed that the chronic exposure in field causes an increase of basal phenoloxidase enzyme activity, while the lytic activity of haemolymph was not affected. As a result, the use of larvicides and fungicides have a harmful effect on beneficial species such C. fuscipes living in the soil of potato fields. These morphological and physiological results recorded at the organismal level can provide useful information of effects at the population and community levels to preserve the biodiversity of agroecosystem.

Low doses of the common alpha-cypermethrin insecticide affect behavioural thermoregulation of the non-targeted beneficial carabid beetle Platynus assimilis (Coleoptera: Carabidae)

Sub-lethal effects of pesticides on behavioural endpoints are poorly investigated in non-targeted beneficial carabids. Conspicuous changes in locomotor activity of carabids exposed to sub-lethal doses of neurotoxic insecticides suggest that many other behaviours of these insects might be severely injured as well. We hypothesize that behavioural thermoregulation of carabids may be affected by low doses of neurotoxic pyrethroid insecticide alpha-cypermethrin which may have direct deleterious consequences for the fitness and populations of the beetles in the field. Automated video tracking of the carabid beetle Platynus assimilis Paykull (Coleoptera: Carabidae) on an experimental thermal mosaic arena using EthoVision XT Version 9 software (Noldus Information Technology, Wageningen, The Netherlands) showed that brief exposure to alpha-cypermethrin at sub-lethal concentrations (0.1-10mgL(-1)) drastically reduces the ability of the beetles for behavioural thermoregulation. At noxious high temperature, a considerable number of the beetles died due to thermo-shock. Other intoxicated beetles that survived exposure to high temperature displayed behavioural abnormalities. During heating of the arena from 25 to 45°C, insecticide treated beetles showed a significant fall in tendency to hide in a cool shelter (20°C) and prolonged exposure to noxious high temperatures, accompanied by changes in locomotor activity. Next day after insecticide treatment the beetles recovered from behavioural abnormalities to a large extent but they still were considerably longer exposed to noxious high temperatures compared to the negative control beetles. Our results demonstrated that behavioural thermoregulation is a sensitive and important etho-toxicological biomarker in ground-dwelling carabids. Prolonged exposure to unfavourably high temperatures has an array of negative effects decreasing fitness and survival of these insects at elevated thermal conditions with deep temperature gradients, typical of agricultural habitats. These results may have importance in IPM programs promoting reduced insecticide use.

Immune challenges trigger cellular and humoral responses in adults of Pterostichus melas italicus (Coleoptera, Carabidae)

The present study focuses on the ability of Pterostichus melas italicus Dejean to mount cellular and humoral immune responses against invading pathogens. Ultrastructural analyses revealed the presence of five morphologically distinct types of hemocytes: prohemocytes, plasmatocytes, granulocytes, oenocytoids and macrophage-like cells. Differential hemocyte counts showed that plasmatocytes and granulocytes were the most abundant circulating cell types and plasmatocytes exhibited phagocytic activity following the latex bead immune challenge. Macrophage-like cells were recruited after the immune challenge to remove exhausted phagocytizing cells, apoptotic cells and melanotic capsules formed to immobilize the latex beads. Total hemocyte counts showed a significant reduction of hemocytes after latex bead treatment. Phenoloxidase (PO) assays revealed an increase of total PO in hemolymph after immune system activation with lipopolysaccharide (LPS). Moreover, the LPS-stimulated hemocytes showed increased protein expression of inducible nitric oxide synthase, indicating that the cytotoxic action of nitric oxide was engaged in this antimicrobial collaborative response. These results provide a knowledge base for further studies on the sensitivity of the P. melas italicus immune system to the environmental perturbation in order to evaluate the effect of chemicals on non-target species in agroecosystems.

Sub-lethal effects of the neurotoxic pyrethroid insecticide Fastac 50EC on the general motor and locomotor activities of the non-targeted beneficial carabid beetle Platynus assimilis (Coleoptera: Carabidae)

BACKGROUND

Sub-lethal effects of pesticides on behavioural endpoints are poorly studied in carabids (Coleoptera: Carabidae) though changes in behaviour caused by chemical stress may affect populations of these non-targeted beneficial insects. General motor activity and locomotion are inherent in many behavioural patterns, and changes in these activities that result from xenobiotic influence mirror an integrated response of the insect to pesticides. Influence of pyrethroid insecticides over a wide range of sub-lethal doses on the motor activities of carabids still remains unclear.

RESULTS

Video tracking of Platynus assimilis showed that brief exposure to alpha-cypermethrin at sub-lethal concentrations ranged from 0.01 to 100 mg L(-1) caused initial short-term (< 2 h) locomotor hyperactivity followed by a long-term (>24 h) locomotor hypo-activity. In addition, significant short- and long-term concentration and time-dependent changes occurred in general motor activity patterns and rates.

CONCLUSION

Conspicuous changes in motor activity of Platynus assimilis beetles treated at alpha-cypermethrin concentrations up to 75,000-fold lower than maximum field recommended concentration (MFRC) suggest that many, basic fitness-related behaviours might be severely injured as well. These changes may negatively affect carabid populations in agro-ecosystems. Long-term hypo-activity could directly contribute to decreased trap captures of carabids frequently observed after insecticide application in the field.