Toxicological and morphological effects of tebufenozide on Anticarsia gemmatalis (Lepidoptera: Noctuidae) larvae

Effects of the insecticide flupyradifurone on Anticarsia gemmatalis caterpillar and its predator Podisus nigrispinus

The caterpillar Anticarsia gemmatalis (Lepidoptera: Noctuidae) is a prevalent pest in soybean plantations, managed using both natural and synthetic chemical products. However, the emergence of resistance in some populations emphasizes the need to explore alternative insecticides. Flupyradifurone, a neurotoxic insecticide, has not been previously used for controlling A. gemmatalis. This study evaluated the potential of flupyradifurone in the management of A. gemmatalis. Initially, the toxicity and anti-feeding effects, as well as histopathological and cytotoxic impacts, of flupyradifurone on A. gemmatalis were evaluated. Subsequently, the indirect effects of flupyradifurone on the midgut and fat body of the predator Podisus nigrispinus (Hemiptera: Pentatomidae) were verified. The results indicate the susceptibility of caterpillars to flupyradifurone, with an LC50 of 5.10 g L-1. Furthermore, the insecticide adversely affects survival, induces an anti-feeding response, and inflicts damage on the midgut of the caterpillars. However, flupyradifurone also leads to side effects in the predator P. nigrispinus through indirect intoxication of the caterpillars, including midgut and fat body damage. While flupyradifurone demonstrates toxicity to A. gemmatalis, suggesting its potential for the chemical control of this pest, the indirect negative effects on the predator indicate the need for its controlled use in integrated pest management programs with the insecticide and the predator.

Synthesis and Antifungal Activity of Novel L-Menthol Hydrazide Derivatives as Potential Laccase Inhibitors

To discover novel laccase inhibitors as potential fungicides, twenty-six novel L-menthol hydrazide derivatives were designed and synthesized. In the in vitro antifungal assay, most of the target compounds displayed pronounced antifungal activity against Sclerotinia sclerotiorum, Fusarium graminearum, and Botryosphaeria dothidea. Especially, the EC50 of compounds 3 b and 3 q against B. dothidea was 0.465 and 0.622 mg/L, which was close to the positive compound fluxapyroxad (EC50 =0.322 mg/L). Scanning electron microscopy (SEM) analysis showed that compound 3 b could significantly damage the mycelial morphology of B. dothidea. In vivo antifungal experiments on apple fruits showed that 3 b exhibited excellent protective and curative effects. Furthermore, in the in vitro laccase inhibition assay, 3 b showed outstanding inhibitory activity with the IC50 value of 2.08 μM, which is much stronger than positive control cysteine and PMDD-5Y. These results indicated that this class of L-menthol derivatives could be promising leads for the discovery of laccase-targeting fungicides.

Sub-lethal effects of spinetoram application interacts with temperature in complex ways to influence respiratory metabolism, life history and macronutrient composition in false codling moth (Thaumatotibia leucotreta)

In many pests, insecticide efficacy is dependent on environmental conditions, including ambient temperature. However, it remains unknown if thermal history alters sub-lethal effects to potentially enhance or reduce pesticide resistance in the false codling moth (FCM), Thaumatotibia leucotreta. Here, using FCM, a pest of economic importance in South Africa infesting several commercial food crops, we report results of sub-lethal exposure to spinetoram, an insecticide that disrupts the nervous system. We investigate whether insecticide efficacy is temperature dependent or perhaps interacts with thermal history by testing the effect of a combination of a sub-lethal dose of spinetoram (4 mg/100 ml) and developmental temperature acclimation (22˚C and 28˚C, i.e., a few degrees above or below optimal development temperatures) on the metabolic rate, life history traits and body composition of FCM in the laboratory. A sub-lethal dose of spinetoram reduced metabolic rate of FCM pupae significantly, led to smaller pupal mass and decreased emergence rates. Additionally, males acclimated at 28 °C had a significantly higher emergence rate compared to males acclimated at 22 °C. Body water, body lipids and body protein reserves of adult FCM tended to be higher in the insecticide treatment compared to the control in the 22 °C acclimation group. In the 28 °C acclimation group, body water, lipids and proteins were lower in the insecticide treatment versus the control. Furthermore, sex influenced both emergence rate and body composition with the direction of change depending on insecticide and temperature treatments. Overall, a sub-lethal dose of spinetoram negatively affects body composition and life history traits but interacts with temperature in complex ways. Therefore, both lethal and sub-lethal effects of spinetoram on FCM, in combination with information on the thermal environment experienced by the pest, should be taken into consideration when pest control decisions are made.

Side-effects of pesticides on non-target insects in agriculture: a mini-review

Climate change mediated by anthropogenic activity induces significant alterations on pest abundance and behavior and a potential increase in the use of agrochemicals for crop protection. Pesticides have been a tool in the control of pests, diseases, and weeds of agricultural systems. However, little attention has been given to their toxic effects on beneficial insect communities that contribute to the maintenance and sustainability of agroecosystems. In addition to pesticide-induced direct mortality, their sublethal effects on arthropod physiology and behavior must be considered for a complete analysis of their impact. This review describes the sublethal effects of pesticides on agriculturally beneficial insects and provides new information about the impacts on the behavior and physiology of these insects. The different types of sublethal effects of pesticides used in agriculture on pollinators, predators, parasitoids, and coprophagous insects were detailed.

Exposure to insecticides causes effects on survival, prey consumption, and histological changes in the midgut of the predatory bug, Podisus nigrispinus (Hemiptera: Pentatomidae)

The control of defoliating caterpillars in forestry includes the use of insecticides and releases of the predatory bug Podisus nigrispinus, but some compounds may affect non-target natural enemies, which need evaluation of risk assessment. This research investigates the survival, preference, and prey consumption of P. nigrispinus adults fed with prey treated with the lethal concentration (LC₅₀) of Bacillus thuringiensis (Bt), permethrin, tebufenozide, and thiamethoxam. Moreover, midgut histopathology of P. nigrispinus fed with preys treated with LC₅₀ of each insecticide was investigated. The insecticides Bt, permethrin, and thiamethoxam reduce the survival and the prey consumption in P. nigrispinus fed with preys contaminate with these chemicals. However, the four tested insecticides, including tebufenozide, cause histological changes such as irregular epithelial architecture, cytoplasm vacuolization, and release of cell fragments in the midgut lumen of P. nigrispinus. The sublethal effects of Bt, permethrin, tebufenozide, and thiamethoxam to the natural enemy suggest that they should be better evaluated to be used together with P. nigrispinus for integrated pest management in forestry.

Susceptibility of the Non-Targeted Crustacean Eurytemora affinis to the Endocrine Disruptor Tebufenozide: A Transcriptomic Approach

Copepods are zooplanktonic crustaceans ubiquitously widespread in aquatic systems. Although they are not the target, copepods are exposed to a wide variety of pollutants such as insect growth regulators (IGRs). The aim of this study was to investigate the molecular response of a non-targeted organism, the copepod Eurytemora affinis, to an IGR. Adult males and females were exposed to two sub-lethal concentrations of tebufenozide (TEB). Our results indicate a sex-specific response with a higher sensitivity in males, potentially due to a differential activation of stress response pathways. In both sexes, exposure to TEB triggered similar pathways to those found in targeted species by modulating the transcription of early and late ecdysone responsive genes. Among them were genes involved in cuticle metabolism, muscle contraction, neurotransmission, and gametogenesis, whose mis-regulation could lead to moult, locomotor, and reproductive impairments. Furthermore, genes involved in epigenetic processes were found in both sexes, which highlights the potential impact of exposure to TEB on future generations. This work allows identification of (i) potential biomarkers of ecdysone agonists and (ii) further assessment of putative physiological responses to characterize the effects of TEB at higher biological levels. The present study reinforces the suitability of using E. affinis as an ecotoxicological model.

Behavioral and ultrastructural effects of novaluron on Aedes aegypti larvae

Chitin synthesis inhibitors (CSI) are supposed to inhibit formation of chitin microfibrils in newly synthesized cuticle during molting process. Conversely, there has been comparatively few data on morphological effects of CSI on non-target insect organs. In this work, the effects of the CSI novaluron on behavior and midgut of A. aegypti were evaluated. Toxicity bioassays revealed that novaluron is toxic to A. aegypti larva with LC₅₀ = 18.57 mg L^-1 when exposed in aqueous solution for 24 h. Novaluron treated larvae were less active and spent more time resting compared to the control group. Histopathology showed that midguts of novaluron-treated larvae had cytoplasm vacuolization and damaged brush border. Cytotoxic effects in midguts of treated larvae induced necrosis, autophagy and damage to mitochondria. Despite being chitin synthesis inhibitor, novaluron did not induce alterations in the integument of A. aegypti larvae. Fluorescence microscopy revealed that the number of digestive cells were higher in novaluron-treated larvae than in control, in response to digestive cell apoptosis. The present study highlights the importance of novaluron against A. aegypti larvae by causing injuries to non-target organs, altering behaviors, inducing cell death and inhibiting cell proliferation.

Deltamethrin-Mediated Effects on Locomotion, Respiration, Feeding, and Histological Changes in the Midgut of Spodoptera frugiperda Caterpillars

Simple Summary

Spodoptera frugiperda is controlled mainly with chemical insecticides. Toxicity, survival, respiration, mobility, anti-feeding effect, and histology of the midgut of S. frugiperda caterpillars exposed to deltamethrin were evaluated. Deltamethrin was toxic to third-instar caterpillars, decreasing survival. The insecticide reduces the respiratory rate and food consumption, and causes repellency. Exposure to deltamethrin causes histological alterations in the midgut, damaging the digestive cells and peritrophic matrix. Deltamethrin is toxic to S. frugiperda caterpillars, causing mortality, alteration of locomotor behavior, reduced respiration and feeding, and irreversible damage to the midgut epithelium.

Abstract

Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is the main pest of maize crops, and effective methods for pest management are needed. The insecticidal efficacy of deltamethrin was evaluated against S. frugiperda for toxicity, survival, locomotion, anti-feeding, and histological changes in the midgut. Concentration–mortality bioassays confirmed that deltamethrin (LC₅₀ = 3.58 mg mL⁻¹) is toxic to S. frugiperda caterpillars. The survival rate was 99.7% in caterpillars not exposed to deltamethrin, decreasing to 50.3% in caterpillars exposed to LC₅₀, and 0.1% in caterpillars treated with LC₉₀. Spodoptera frugiperda demonstrated reduced mobility on deltamethrin-treated surfaces. Deltamethrin promoted a low respiration rate of S. frugiperda for up to 3 h after insecticide exposure, displaying immobilization and inhibiting food consumption. Deltamethrin induces histological alterations (e.g., disorganization of the striated border, cytoplasm vacuolization, and cell fragmentation) in the midgut, damaging the digestive cells and peritrophic matrix, affecting digestion and nutrient absorption.

Spiromesifen induces histopathological and cytotoxic changes in the midgut of the honeybee Apis mellifera (Hymenoptera: Apidae)

The honeybee Apis mellifera is an important pollinator that, similarly to other bees, undergoes colony losses due to several problems, including the use of pesticides in the agriculture. In addition to direct mortality, pesticides cause side-effects in some non-target organs, such as the midgut, which is the main organ for digestion and absorption. Spiromesifen is a pesticide used to control mites and whiteflies, which can be ingested by bees feeding on contaminated floral resources. This study evaluated the histopathological and cytological effects of the ingestion of spiromesifen on the midgut of A. mellifera workers. The bees were exposed per os to the field recommended dose of spiromesifen, and the midgut was analyzed after 24h and 48h of exposure to the pesticide. The midgut has a single layer of digestive cells, with spherical nucleus, nests of regenerative cells and layers of peritrophic matrix in the lumen. Bees treated with spiromesifen presented histological and cytological changes in the midgut, including disorganization of the epithelial architecture, release of cell fragments to the lumen, accumulation of mitochondria in the apical cytoplasm, alteration of the basal labyrinth, changes in the rough endoplasmic reticulum and cell degeneration. The occurrence of damage in the digestive cells of the A. mellifera midgut indicates that spiromesifen does not cause mortality in honeybees, but its side-effects can damage the midgut, which may affect the longevity and behavior of this pollinator.

Exposure to chlorantraniliprole reduces locomotion, respiration, and causes histological changes in the midgut of velvetbean caterpillar Anticarsia gemmatalis (Lepidoptera: Noctuidae)

The anthranilic diamide, chlorantraniliprole is a systemic insecticide affecting ryanodine receptors. This insecticide is used to control caterpillars in soybean crops because it has low toxicity to non-target organisms. The objective was to identify side-effects of chlorantraniliprole on midgut histopathology, respiration and behavior of the velvetbean caterpillar Anticarsia gemmatalis in laboratoty. Chlorantraniliprole has LC50 = 0.61 (0.58-0.64) mg mL-1 for A. gemmatalis fourth instar caterpillars after 96 h. The insecticide causes severe histopathological effects in the midgut with epithelial disorganization, microvilli degeneration, cytoplasm vacuolization, cell fragmentation, and peritrophic matrix disorganization. The respiratory rate and the walking speed decrease, whereas the resting period increase for caterpillars exposed to this insecticide. Chlorantraniliprole is toxic to A. gemmatalis at median lethal concentrations causing severe histological and ultrastructural changes with degeneration of the midgut epithelium, reduction of respiratory rates and inducing an arresting behavioral response of this insect.

Respiration, predatory behavior and prey consumption by Podisus nigrispinus (Heteroptera: Pentatomidae) nymphs exposed to some insecticides

Podisus nigrispinus Dallas (Heteroptera: Pentatomidae) preys on insect pests in eucalyptus plantations where it can be exposed to insecticides used in pest control. The effect of insecticides on non-target natural enemies requires further study. The objective of the present study was to evaluate the side-effects of Bacillus thuringiensis (Bt), permethrin, tebufenozide and thiamethoxam on third instar nymphs of the predator P. nigrispinus in the laboratory. The toxicity of insecticides for this insect was determined by estimating their lethal concentrations. Podisus nigrispinus behavior after exposure to insecticides was analyzed using a video tracking system and the respiratory rate with a respirometer. Prey/nymph consumption was assessed after 24 h of starvation. The preference of P. nigrispinus nymphs, for prey treated or not with the insecticides, was evaluated in free choice tests. The insecticides Bt [LC₅₀ = 1.10(0.83-1.46) mg mL^-1], permethrin [LC₅₀ = 0.25(0.17-0.34) mg mL^-1], tebufenozide [LC₅₀ = 5.71(4.17-7.57) mg mL^-1] and thiamethoxam [LC₅₀ = 0.04(0.02-0.06) mg mL^-1] are toxic to P. nigrispinus nymphs. Bt and the insecticides tebufenozide, permethrin and thiamethoxam reduced the respiratory rate of P. nigrispinus. The insecticides permethrin, tebufenozide and thiamethoxam affect the locomotion of this insect's nymphs. Prey treated with Bt, permethrin and thiamethoxam are less preferred by P. nigrispinus. The survival of the nymphs of this predator was 93.3%, 66.7%, 56.6%, 0% and 0% in the control, tebufenozide, Bt, permethrin and thiamethoxam treatments, respectively. In addition, the reduction of prey consumption, treated with neurotoxic insecticides, reduces the predatory potential of this natural enemy. Bt and tefubenozide present low toxicity for P. nigrispinus, but the neurotoxic products have low compatibility with this natural enemy and, therefore, are not recommended, with this predator in the management of forest insect pests.

Acute Toxicity and Sublethal Effects of Lemongrass Essential Oil and Their Components against the Granary Weevil, Sitophilus granarius

In the present work, we evaluate the toxic and repellent properties of lemongrass (Cymbopogon citratus (DC. ex Nees) Stapf.) essential oil and its components against Sitophilus granarius Linnaeus as an alternative to insecticide use. The lethal dose (LD50 and LD90), survivorship, respiration rate, and repellency on adults of S. granarius exposed to different doses of lemongrass oil and some of its components were evaluated. The chemical composition of the essential oil was found to have the major components of neral (24.6%), citral (18.7%), geranyl acetate (12.4%), geranial (12.3%), and limonene (7.55%). Lemongrass essential oil (LD50 = 4.03 µg·insect-1), citral (LD50 = 6.92 µg·insect-1), and geranyl acetate (LD50 = 3.93 µg·insect-1) were toxic to S. granarius adults. Survivorship was 99.9% in insects not exposed to lemongrass essential oil, decreasing to 57.6%, 43.1%, and 25.9% in insects exposed to LD50 of essential oil, citral, and geranyl acetate, respectively. The insects had low respiratory rates and locomotion after exposure to the essential oil, geranyl acetate, and citral. Our data show that lemongrass essential oils and their components have insecticidal and repellent activity against S. granarius and, therefore, have the potential for application in stored grain pest management schemes.

Side effects of Bacillus thuringiensis on the parasitoid Palmistichus elaeisis (Hymenoptera: Eulophidae)

The endoparasitoid wasp Palmistichus elaeisis Delvare & LaSalle (Hymenoptera: Eulophidae) is used to control defoliating lepidopteran pests. Chemical insecticides are not compatible with natural enemies, but bioinsecticides, such as Bacillus thuringiensis Berliner (Bt), have great potential for use in integrated pest management. However, interactions between Bt and P. elaeisis still need to be investigated. This study aimed to evaluate the effects of Bt on parental and first-generation P. elaeisis parasitizing Bt-susceptible and -resistant Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). An additional aim was to determine the toxicity of Bt to susceptible third-instar S. frugiperda larvae. Larvae were exposed to lethal concentrations (LC₅₀ and LC₉₀) of Bt and then allowed to be parasitized by P. elaeisis. Parasitoid longevity, immature production, reproductive performance, and behavioral responses were evaluated. Bt repelled P. elaeisis and reduced immature production. Parental and first filial generation parasitoids of both sexes emerged from Bt-treated larvae showed lower survivorship than controls. Parasitoids had poorer reproductive performance in Bt-susceptible and -resistant pupae than in untreated pupae. Palmistichus elaeisis emerged from Bt-susceptible and -resistant S. frugiperda showed altered host-searching behavior and reproductive parameters, which indicates low compatibility between the bioinsecticide agent and the parasitoid wasp.

The fungicide iprodione affects midgut cells of non-target honey bee Apis mellifera workers

The honey bee Apis mellifera is an important pollinator of agricultural crops and natural forests. Honey bee populations have declined over the years, as a result of diseases, pesticides, and management problems. Fungicides are the main pesticides found in pollen grains, which are the major source of protein for bees. The objective of this study was to evaluate the cytotoxic effects of the fungicide iprodione on midgut cells of adult A. mellifera workers. Bees were fed on iprodione (LD₅₀, determined by the manufacturer) for 12 or 24 h, and the midgut was examined using light and transmission electron microscopies. The expression level of the autophagy gene atg1 was assessed in midgut digestive cells. Cells of treated bees had signs of apoptosis: cytoplasmic vacuolization, apical cell protrusions, nuclear fragmentation, and chromatin condensation. Ultrastructural analysis revealed some cells undergoing autophagy and necrosis. Expression of atg1 was similar between treated and control bees, which can be explained by the facts that digestive cells had autolysosomes, whereas ATG-1 is found in the initial phases of autophagy. Iprodione acts by inhibiting the synthesis of glutathione, leading to the generation of reactive oxygen species, which in turn can induce different types of cell death. The results indicate that iprodione must be used with caution because it has side effects on non-target organisms, such as pollinator bees.

The comparative metabolic response of Bactrocera dorsalis larvae to azadirachtin, pyriproxyfen and tebufenozide

Azadirachtin, as the most promising and effective botanical insecticide, exhibits significant growth inhibition activity against agricultural and forestry pests. However, its biochemical effects at the metabolic level compared with those of other insect growth regulators have not been studied. Therefore, in this study, a GC-MS based untargeted metabolomics approach was applied to compare azadirachtin with pyriproxyfen (a juvenile hormone analog) and tebufenozide (a molting hormone analog) in terms of their metabolic effects on Bactrocera dorsalis larvae. The bioactivity of azadirachtin against B. dorsalis larvae was significantly different than those of pyriproxyfen and tebufenozide. A total of 693 mass features were recognized, and 112 metabolites were identified in this study. The results showed that a total of 16, 13 and 10 differentially regulated metabolites corresponding to 12, 5 and 8 pathways occur in Aza versus CK, Pyr versus CK and Teb versus CK group, respectively. Further analysis showed that 6 differentially regulated metabolites corresponding to 5 key pathways could be the primary differential metabolic response of B. dorsalis larvae to the three insect growth regulators. The pathways were myo-inositol corresponding to ascorbate and aldarate metabolism as the specific response of B. dorsalis larvae to azadirachtin; xylitol, xylulose and 3-aminopropionitrile corresponding to pentose and glucuronate interconversions, and cyanoamino acid metabolism as the common responses to azadirachtin and pyriproxyfen; and 3-hydroxypropionic acid and beta-alanine corresponding to propanoate metabolism and beta-alanine metabolism as the specific responses to tebufenozide. The results showed that the metabolic response of B. dorsalis larvae to azadirachitin is closer to that of pyriproxyfen than tebufenozide. The differentially regulated metabolites and pathways responsible for this difference are discussed.

Histopathological and cytotoxic changes induced by spinosad on midgut cells of the non-target predator Podisus nigrispinus Dallas (Heteroptera: Pentatomidae)

Broad-spectrum insecticides used in pest control are a risk for non-target insects. Their compatibility to the insecticide spinosad, used in agriculture and forestry as a biological control tool, needs to be evaluated. Podisus nigrispinus Dallas (Heteroptera: Pentatomidae) is a predatory bug used in the pest management of agricultural and forest systems where spinosad is also frequently applied. The aim of this study was to evaluate the toxicity, histopathology and cytotoxicity in midgut cells of P. nigrispinus exposed to spinosad. The toxicity test was performed to determine the lethal concentrations of spinosad after exposure by ingestion. The histopathology and cytotoxicity caused by spinosad were analyzed in the three midgut regions (anterior, middle and posterior) of P. nigrispinus during different exposure periods. Spinosad, at low concentrations, was toxic to P. nigrispinus [LC₅₀ = 3.15 (3.02-3.26) μg.L^-1]. Cell degeneration features such as cytoplasm vacuolization, chromatin condensation and release of cell fragments to the midgut lumen were observed in this organ. Cell death via apoptosis was found in the three midgut regions of this predator after exposure to the insecticide. Spinosad is toxic to P. nigrispinus, and causes histological and cytological damage followed by cell death in the midgut, suggesting a dangerous effect on a beneficial non-target insect.

Pyriproxyfen, a juvenile hormone analog, damages midgut cells and interferes with behaviors of Aedes aegypti larvae

Juvenile hormone analogs (JHA) are known to interfere with growth and biosynthesis of insects with potential for insecticide action. However, there has been comparatively few data on morphological effects of JHA on insect organs. To determine pyriproxyfen effects on Aedes aegypti larvae, we conducted toxicity, behavioral bioassays and assessed ultrastructural effects of pyriproxyfen on midgut cells. A. aegypti larvae were exposed in aqueous solution of pyriproxyfen LC₅₀ concentrations and evaluated for 24 h. This study fulfilled the toxic prevalence of pyriproxyfen to A. aegypti larvae (LC₅₀ = 8.2 mg L^-1). Behavioral observations confirmed that pyriproxyfen treatment significantly changes swimming behavior of larvae, limiting its displacement and speed. The pyriproxyfen causes remarkable histopathological and cytotoxic alterations in the midgut of larvae. Histopathological study reveals presence of cytoplasmic vacuolization and damage to brush border of the digestive cells. The main salient lesions of cytotoxic effects are occurrence of cell debris released into the midgut lumen, cytoplasm rich in lipid droplets, autophagosomes, disorganized microvilli and deformed mitochondria. Data suggest that pyriproxyfen can be used to help to control and eradicate this insect vector.

Using controlled vocabularies in anatomical terminology: A case study with Strumigenys (Hymenoptera: Formicidae)

Morphological studies of insects can help us to understand the concomitant or sequential functionality of complex structures and may be used to hypothetize distinct levels of phylogenetic relationship among groups. Traditional morphological works, generally, have encompassed a set of elements, including descriptions of structures and their respective conditions, literature references and images, all combined in a single document. Fast forward to the digital era, it is now possible to release this information simultaneously but also independently as data sets linked to the original publication in an external environment. In order to link data from various fields of knowledge, disseminating morphological information in an open environment, it is important to use tools that enhance interoperability. For example, semantic annotations facilitate the dissemination and retrieval of phenotypic data in digital environments. The integration of semantic (i.e. web-based) components with anatomic treatments can be used to generate a traditional description in natural language along with a set of semantic annotations. The ant genus Strumigenys currently comprises about 840 described species distributed worldwide. In the Neotropical region, almost 200 species are currently known, but it is possible that much of the species' diversity there remains unexplored and undescribed. The morphological diversity in the genus is high, reflecting an extreme generic reclassification that occurred in the late 20th and early 21st centuries. Here we define the anatomical concepts in this highly diverse group of ants using semantic annotations to enrich the anatomical ontologies available online, focussing on the definition of terms through subjacent conceptualization.

Exposure to cyantraniliprole causes mortality and disturbs behavioral and respiratory responses in the coffee berry borer (Hypothenemus hampei)

BACKGROUND

Hypothenemus hampei Ferrari (Coleoptera: Curculionidae) is the main pest of coffee due to the damage caused to coffee berries. Effective management methods and prevention of insecticide resistance are urgently needed against this insect. Bioassays were conducted to assess the effects of the diamide insecticide cyantraniliprole on H. hampei. Cyantraniliprole is the most recent compound registered against this species after the phasing out of endosulfan, the main insecticide historically used against the coffee borer for the past 30 years. Toxicity, survival, progeny production, respiration rate, and behavioral responses to cyantraniliprole were evaluated.

RESULTS

Cyantraniliprole was toxic to adult H. hampei (LC₅₀  = 0.67 mg mL^-1 and LC₉₀  = 1.71 mg mL^-1 ). Adult survival was 95% without exposure to cyantraniliprole, decreasing to 52% in insects exposed to LC₅₀ cyantraniliprole and 27% in insects treated with LC₉₀ cyantraniliprole. Furthermore, H. hampei showed reduced mobility on insecticide-treated surfaces. The insecticide also led to a decrease in the respiration rate of H. hampei for up to 3 h after exposure, altering behavioral responses and locomotor activity.

CONCLUSION

Cyantraniliprole exhibits lethal and sublethal effects on H. hampei and can be used in rotation in integrated pest management programs for control of this species in coffee cultivation systems. © 2019 Society of Chemical Industry.

Chlorantraniliprole degenerates microvilli goblet cells of the Anticarsia gemmatalis (Lepidoptera: Noctuidae) midgut

Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae) is mainly controlled with synthetic insecticides such as chlorantraniliprole. However, these compounds may affect non-target organs of insect metabolism. The objective of this study was to evaluate the toxic effect in the midgut goblet cells of A. gemmatalis caterpillars exposed to chlorantraniliprole. The midgut of these caterpillars, which ingested the insecticide in medium-lethal dose (LD₅₀), was dissected and evaluated by transmission electron microscopy. The goblet cells microvilli, after exposure to the insecticide, were disorganized and degenerated. This can compromise ionic homeostasis and nutrient absorption, impair physiological mechanisms of detoxification, and reduce the movement of food boluses throughout the insect midgut.

Bioactivity of the Cymbopogon citratus (Poaceae) essential oil and its terpenoid constituents on the predatory bug, Podisus nigrispinus (Heteroptera: Pentatomidae)

Podisus nigrispinus Dallas (Heteroptera: Pentatomidae), released in biological control programs, is a predator of Lepidopteran and Coleopteran species. Lemongrass essential oil and its constituents can be toxic to this natural enemy. The major constituents of lemongrass essential oil are neral (31.5%), citral (26.1%), and geranyl acetate (2.27%). Six concentrations of lemongrass essential oil and of its citral and geranyl acetate constituents were applied to the thorax of P. nigrispinus nymphs and adults. The walking and respiratory behavior of the P. nigrispinus third-instar nymphs, treated with citral and geranyl acetate at the LD50 and LD90 doses, were analyzed with video and respirometer. The lemongrass essential oil toxicity increased from first- to fifth-instar P. nigrispinus nymphs. The P. nigrispinus respiration rates (μL de CO2 h-1/insect) with citral and geranyl acetate in the LD50 and LD90 differed. Nymphs exposed to the lemongrass essential oil and its constituents on treated surfaces presented irritability or were repelled. Podisus nigrispinus adults were tolerant to the lemongrass essential oil and its constituents, geranyl acetate and citral. The altered respiratory activity with geranyl acetate and the fact that they were irritated and repelled by citral suggest caution with regard to the use of the lemongrass essential oil and its constituents in integrated pest management incorporating this predator, in order to avoid diminishing its efficiency against the pests.

Exposure to spinosad induces histopathological and cytotoxic effects on the salivary complex of the non-target predator Podisus nigrispinus

In integrated pest management systems, biological and chemical controls must be compatible. The insecticide spinosad affects some non-target insects and might compromise their fitness. The objective of this study was to evaluate the histopathological and cytotoxic effects of spinosad on the salivary complex of the predatory bug Podisus nigrispinus (Heteroptera: Pentatomidae). Spinosad toxicity and insect survival were determined using six concentrations of insecticide. Ultrastructural changes and cell death of salivary glands were analyzed after P. nigrispinus exposure to spinosad LC₅₀ (3.15 μg L^-1). The insecticide caused toxicity to P. nigrispinus; survival was 32% after 48 h of exposure to LC₅₀. The main histological changes in the salivary complex were disorganization of the epithelium, cytoplasmic vacuolization, and apocrine secretion into the gland lumen. Cytotoxic effects, such as release of granules and vacuoles into the lumen, presence of autophagosomes, enlargement of basal plasma membrane infoldings, and apoptosis, were observed. Spinosad causes toxicity, decreases survival, and changes the histology and cytology of the P. nigrispinus salivary complex. The results suggest that the cellular stress induced by the insecticide affects extra-oral digestion, compromising the potential of P. nigrispinus as a biological pest control agent.

Chlorantraniliprole-mediated effects on survival, walking abilities, and respiration in the coffee berry borer, Hypothenemus hampei

Hypothenemus hampei Ferrari (Coleoptera: Curculionidae) is the main pest of coffee crops, and effective methods for pest management are needed urgently. Bioassays were conducted to assess the effects of the insecticide chlorantraniliprole on H. hampei adults. Toxicity, survivorship, larval production, respiration rate, and behavioral responses to six concentrations of chlorantraniliprole were evaluated. Chlorantraniliprole was toxic to H. hampei (LD₅₀ = 0.49 mg mL^-1 and LD₉₀ = 1.21 mg mL^-1). Survivorship was 98% in adults not exposed to chlorantraniliprole, decreasing to 52% in insects exposed to LD₅₀ and 2% in insects treated with LD₉₀. H. hampei showed reduced mobility on insecticide-treated surfaces. The insecticide promoted a decrease in the respiration rate of H. hampei for up to 3 h after exposure, altering behavioral responses and locomotor activity. Chlorantraniliprole was shown to have lethal and sublethal effects on H. hampei and, thus, can be used rotationally in integrated pest management programs to control of this pest in coffee crops and retard of insect resistance.

Toxicity and cytotoxicity of the insecticide imidacloprid in the midgut of the predatory bug, Podisus nigrispinus

The selectivity of insecticides on natural enemies in pest control are an important strategy for Integrated Pest Management. However, insecticides can have side effects on non-target organisms such as natural enemies. This study evaluated the histological and cytological changes mediated by the sublethal concentration of the imidacloprid insecticide on the midgut of non-target predator Podisus nigrispinus (Heteroptera: Pentatomidae), used in the biological control of pests. Imidacloprid was toxic for P. nigrispinus with LC₅₀ = 3.75 mg L^-1 and survival of 51.8%. This sublethal concentration of imidacloprid causes histological alterations in the midgut epithelium and cytotoxic features were irregular border epithelium, cytoplasmic vacuolation, and apocrine secretions in the first 6 h after exposure with the insecticide. Apoptosis in the digestive cells occurs after 12 h of exposure in the midgut. These results suggest that imidacloprid may affect the digestive physiology of P. nigrispinus and compromise the effective predation of this insect a biological control agent. The associated use of this insecticide with the predator in pest control should be carefully evaluated.