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The honey bee Apis mellifera plays a significant role as a pollinator of native and cultivated plants, by increasing the productivity of several cultures, preserving the flora, and producing forest seeds. However, bee populations are declining worldwide, including A. mellifera, due to Colony Collapse Disorder, mainly resulting from the constant use of pesticides in the crops. Teflubenzuron is a physiological insecticide that belongs to the benzoylurea group, which inhibits chitin synthesis, the main component of the insect integument classified as safe for non-target insects, including bees. However, its effect on non-target organs of insects remains unknown. The midgut is the main organ of the digestive tract, which works in digestion and absorption and may be exposed to pesticides that contaminate food resources. The present work aimed to verify if the insecticide teflubenzuron is toxic and has histopathological effects on the midgut of A. mellifera adult workers. Workers exposed orally and chronically to the field-realistic concentration of teflubenzuron present 81.54% mortality. The epithelium of the midgut of these bees presents high vacuolization, spherocrystals, cell fragments released to the organ lumen, apocrine secretion, nuclear pyknosis, loss of cell-cell contact, and damage to regenerative cell nests and to the peritrophic matrix. These results indicate that the chitin synthesis-inhibiting insecticide teflubenzuron is toxic to A. mellifera after chronic oral exposure, at realistic field concentration, although it is classified as non-toxic to adult and non-target insects.

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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.

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Bees are important for maintaining ecosystems, pollinating crops and producing marketable products. In recent years, a decline in bee populations has been reported, with multifactorial causes, including the intensification of pesticide use in agriculture. Among pesticides, cyflumetofen is an insecticide and acaricide used in apple, coffee and citrus crops, whose main pollinator is the honey bee Apis mellifera. Therefore, this bee is a potential target of cyflumetofen during foraging. This study evaluated the histopathological and cytological damage in the midgut, hypopharyngeal glands and fat body of A. mellifera workers exposed to LC50 of cyflumetofen. The midgut epithelium of exposed bees presented cytoplasmic vacuolization, release of vesicles and cell fragments, which indicate autophagy, increased production of digestive enzymes and cell death, respectively. The cytological analysis of the midgut revealed the dilation of the basal labyrinth and the presence of spherocrystals in the digestive cells. The hypopharyngeal glands produced greater amounts of secretion in treated bees, whereas no changes were observed in the fat body. The results indicate that acute exposure to cyflumetofen negatively affect A. mellifera, causing damage to the midgut and changes in the hypopharyngeal glands, which may compromise the survival and foraging of this pollinator.

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The stingless bee Partamona helleri plays a role in pollinating both native and cultivated plants in the Neotropics. However, its populations can be reduced by the pyrethroid insecticide lambda-cyhalothrin. This compound may cross the intestinal barrier and circulate through the hemolymph, affecting various non-target bee organs. The aim of the present study was to assess the extent of cellular damage in the midgut and the resulting oxidative stress caused by lambda-cyhalothrin in P. helleri workers. Bees were orally exposed to lambda-cyhalothrin. The lethal concentration at which 50% of the bees died (LC50) was 0.043 mg a.i. L-1. The P. helleri workers were fed this concentration of lambda-cyhalothrin and their midguts were evaluated. The results revealed signs of damage in the midgut epithelium, including pyknotic nuclei, cytoplasm vacuolization, changes in the striated border, and the release of cell fragments, indicating that the midgut was compromised. Furthermore, the ingestion of lambda-cyhalothrin led to an increase in the activity of the detoxification enzyme superoxide dismutase and the levels of the NO2/NO3 markers, indicating oxidative stress. Conversely, the activities of the catalase and glutathione S-transferase enzymes decreased, supporting the occurrence of oxidative stress. In conclusion, the ingestion of lambda-cyhalothrin by P. helleri workers resulted in damage to their midguts and induced oxidative stress.

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Apis mellifera is an important bee pollinating native and crop plants but its recent population decline has been linked to the use of pesticides, including fungicides that have been commonly classified as safe for bees. However, many pesticides, in addition to direct mortality cause sublethal effects, including damage to target selective honey bee organs. The midgut is the organ responsible for the digestion and absorption of nutrients and the detoxification of ingested substances, such as pesticides. This study evaluated the histopathological and cytotoxic changes in the midgut of A. mellifera workers caused by the pesticide azoxystrobin. The limit-test was performed, and a 100 µg a.i./bee dose was administered orally and midgut analyzed with light and transmission electron microscopies after 24 h and 48 h of pesticide exposure. The midgut of the control bees has a single layer of digestive cells, with spherical nuclei, nests of regenerative cells, and the lumen coated with the peritrophic matrix. The bees fed on azoxystrobin showed morphological changes, including intense cytoplasm vacuolization and cell fragments released into the gut lumen. The protein detection test showed greater staining intensity in the nests of regenerative cells after 24 h of exposure to azoxystrobin. The occurrence of damage to the midgut in A. mellifera exposed to azoxystrobin indicates that although this fungicide has been classified as low toxicity for bees, it has sublethal effects in the midgut, and effects in other organs should be investigated.

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The sugarcane borer Diatraea saccharalis (Lepidoptera: Crambidae) is an important sugarcane pest and mechanical injuries caused through the mandibles can allow pathogen infections. The mandibles of D. saccharalis, as well as other insects, are associated with mandibular glands with a possible function in food intake and mouthparts lubrication; however, the chemical composition of the secretion is poorly known and its elucidation is important for the comprehensive understanding of plant-insect interactions. This study characterized some proteins and volatiles in the mandibular glands of D. saccharalis larvae. MALDI-TOF/TOF mass spectrometry allowed the identification of 24 predicted proteins within 10 functional classes, including the transport and metabolism of carbohydrates, lipids, amino acids, and nucleotides; Posttranslational protein modifications; energy conversion; intracellular trafficking; transcription; translation; and cytoskeleton function. Metabolites identified from GC/MS analysis revealed the presence of hydrocarbons classified as alcohols, ether, alkanes, and esters with differences in their relative abundance. Linolenic acid, the most abundant metabolite found in this gland, when conjugated with amino acids, can be an elicitor in the plant-herbivore interaction. The results suggest the occurrence of digestive and defensive biochemical components, which may contribute to understanding of the multifunctional roles of the mandibular gland secretion of D. saccharalis larvae during feeding activity.

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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.

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The honey bee Apis mellifera is an important pollinator that increases the yield and quality of crops. In recent years, honey bee populations have declined in some parts of the world, which has been associated with several causes, including pesticides used in agriculture. Neonicotinoids are neurotoxic insecticides widely used in the world with systemic action mode contaminating nectar and pollen that may be consumed by bees. This study evaluated the side effects of imidacloprid in the midgut of A. mellifera after acute oral exposure. Toxicity, histopathology, cytotoxicity, and expression of autophagy-related gene atg1 were evaluated in honey bee workers orally exposed to imidacloprid. The estimated imidacloprid LC50 was 1.44 mg L-1. The midgut epithelium of bees fed on imidacloprid LC50 has the occurrence of cytoplasm vacuoles, enlarged intercellular spaces, disorganization of the striated border, and nuclear pyknosis, with an organ injury index that increases with time exposure. The midgut digestive cells of treated bees have apical protrusions, damaged mitochondria, and autophagosomes that were characterized for content with organelle debris and high expression of atg1. These features indicate the occurrence of high cell death in the midgut of workers exposed to imidacloprid, which may affect the digestibility the physiology of the insect.

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Forestry pest management includes biological and chemical methods of pest control. Using insecticides and natural enemies can be compatible in forest pest management programs. The compatibility of the predatory stink bug Podisus distinctus with the insecticide indoxacarb, used in forestry, needs to be evaluated in Brazil. This study investigated the mortality, survival, respiration, preference, prey consumption, and locomotor activity of P. distinctus adults exposed to indoxacarb. In concentration-mortality bioassays, the lethality of indoxacarb (LC50 = 2.62 g L-1 and LC90 = 6.11 g L-1) was confirmed in P. distinctus adults. The survival rate was 100% in predator insects not exposed to indoxacarb, declining to 40.7% in predator insects exposed to 2.62 g L-1 and 0.1% in predators treated with 6.11 g L-1. Indoxacarb reduced the respiration of P. distinctus from 18.45 to 14.41 µL CO2 h-1 at 2.62 g L-1 for up to 3 h after insecticide exposure, inhibiting food consumption and displaying hyperexcitation. The harmful effects of indoxacarb to the natural enemy suggest that it should be better assessed for use with P. distinctus for pest management in forestry.

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BACKGROUND: The potential of Beauveria bassiana and Metarhizium anisopliae isolates obtained from naturally infected oil palm pests was evaluated to control Demotispa neivai as an alternative for organophosphate insecticide use in oil palm crops in Latin America. Two B. bassiana (Bb-0018 and Bb-0025) and two M. anisopliae (Ma-0002 and Ma-0003) isolates were tested against D. neivai adults for hydrophobicity, virulence, survival, adhesion to host cuticle, and mortality in semi-field conditions. RESULTS: Concentration-mortality bioassays demonstrate that isolates had lethal effect on D. neivai adults with Bb-0025 [median lethal concentration (LC50 ) = 3.45 × 107 conidia mL-1 ] and Bb-0018 (LC50  = 3.75 × 107 conidia mL-1 ) being the most effective followed by Ma-0003 (LC50  = 3.38 × 108 conidia mL-1 ) and Ma-0002 (5.33 × 108 conidia mL-1 ). Adult survival was 99% without exposure to fungal isolates, decreasing to 21.65% in insects exposed to Ma-0002, 19.41% with Ma-0003, 20.13% with Bb-0018, and 0.17% with Bb-0025. Mortality of D. neivai adults caused by the entomopathogenic fungal isolates was similar in both laboratory and semi-field conditions. Also, vegetative growth of the entomopathogenic fungal isolates was found in infected D. neivai adults in the field. CONCLUSION: Our data suggest that the tested entomopathogenic fungal isolates are effective against D. neivai with potential to be used as biological control agents contributing to the decrease of the use of chemical insecticides to control this oil palm pest. © 2021 Society of Chemical Industry.

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Resumen INTRODUCCIÓN: En Estados Unidos, las cardiopatías periparto se registran en 1 de cada 4000 pacientes. Se consideran idiopáticas y se asocian con enfermedades genéticas, problemas inmunológicos y malformaciones cardiacas, sin que se tenga certeza del origen real de este tipo de enfermedades. La miocardiopatía periparto se asocia con el embarazo y el puerperio; los criterios diagnósticos incluyen: a) insuficiencia cardiaca en las últimas cuatro semanas del embarazo o en los cinco meses siguientes al parto, b) ausencia de causas identificables de insuficiencia cardiaca, c) ausencia de enfermedad cardiaca demostrable antes de las últimas cuatro semanas del embarazo y alteración de la función del ventrículo izquierdo (fracción de eyección del ventrículo izquierdo, menor del 45%). La presentación del caso ayudará a que se tenga conocimiento de este problema. CASO CLINICO: Paciente de 26 años, en curso de las 35.4 semanas de embarazo, con inicio abrupto de signos de cardiopatía congestiva: tos, edema, taquicardia e hipertensión arterial. El embarazo finalizó por cesárea, con traslado inmediato a la unidad de cuidados intensivos. La ecocardiografía reportó una valvulopatía no conocida, insuficiencia ventricular izquierda y disminución de la fracción de eyección del ventrículo izquierdo; con lo anterior se integró el diagnóstico de miocardiopatía periparto. CONCLUSIONES: Las cardiopatías periperiparto son alteraciones excepcionales, con cuadros clínicos debidamente definidos y diagnóstico complejo. Las valvulopatías son el último diagnóstico diferencial de cardiopatía congestiva peripuerperal y se han descrito pocos casos asociados con miocardiopatía periparto.

Abstract BACKGROUND: Peripartum heart disease occurs in 1 out of 4000 cases in the United States; currently, its exact origin is unknown, which is why they are called idiopathic. Genetic diseases, immunological problems and heart malformations have been associated, without being certain about the real origin of these pathologies. Peripartum cardiomyopathy is a rare pathology associated with pregnancy and the puerperium, the diagnosis criteria includes: a) Development of heart failure in the last month of pregnancy or in the 5 months after delivery, b) absence of identifiable causes of heart failure, c) absence of demonstrable heart disease prior to the last month of pregnancy and impaired left ventricular function (FEVI less than 45%). The presentation of the case will help to raise awareness about this problem. CLINICAL CASE: A 26-year-old female patient coursing second gestation in the 35.4 pregnancy week, who debuts abruptly with signs of congestive heart disease such as cough, edema, tachycardia and arterial hypertension. The pregnancy was solved by cesarean section with a subsequent stay in Intensive Care Unit, an unknown valvular disease was identified by echocardiography, as well as left ventricular failure and decreased FEVI. Finally, a definitive diagnosis of peripartum cardiomyopathy was integrated. CONCLUSIONS: Peripartum heart disease is a rare occurrence, with well-defined clinical pictures, but difficult to approach and diagnose. Where valvular heart disease is the last differential diagnosis for peripuerperal congestive heart disease, and few cases associated with peripartum cardiomyopathy have been described.

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Tenebrio molitor is one of the main stored product pests. This study characterized oregano essential oil (OEO) by gas chromatography (GC/FID and GC/MS) and assessed its insecticidal properties against T. molitor. Mortality, survival, respiration, and behavioral response in larva, pupa, and adult of this insect were determined. The major components of OEO were carvacrol (25.6%), p-cymene (12.3%), linalool (8.71%), thymol (7.22%), γ-terpinene (7.21%), caryophyllene oxide (4.67%), α-pinene (2.71%), and eucalyptol (2.69%). OEO caused high contact toxicity in larvae (LD50 = 3.03 µg insect-1), pupae (LD50 = 5.01 µg insect-1), and adults (LD50 = 5.12 µg insect-1) of T. molitor. Survival rates were 100% in larvae, pupae, and adults of T. molitor not treated with OEO, declining to 65-54%, 38-44%, 30-23%, and 6-2% in insects treated with LD25, LD50, LD75, and LD90, respectively. Low respiration rates of T. molitor at different developmental stages was observed after OEO exposure. Additionally, OEO exposure affects behavioral avoidance response and causes repellency in larvae and adults. These findings show that OEO exerts insecticidal and repellent effects against T. molitor, suggesting a potent alternative to synthetic insecticides for controlling the beetle.

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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.

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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.

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The management of the Neotropical brown stinkbug Euschistus heros (Hemiptera: Pentatomidae) in soybean fields has been heavily dependent on the application of neonicotinoid insecticides. Neonicotinoids act primarily by impairing the function of the nicotinic acetylcholine receptors of the nervous system. These compounds also target specific organs (e.g., salivary glands), which may potentiate their insecticidal efficacy. Here, we evaluated whether the exposure to the neonicotinoid imidacloprid would cause cytomorphological changes in the salivary glands of E. heros. First, we determined the lethal concentrations (LCs) of imidacloprid through contact and ingestion. Subsequently, the cytomorphology of the salivary glands were evaluated in insect groups that survived exposure to the LC5 (3.75 mg a.i./L), LC50 (112.5 mg a.i./L), or LC75 (375.0 mg a.i./L, equivalent to the recommended field rate) doses. Imidacloprid induced apoptosis and necrosis in the salivary gland cells according to the insecticide concentration and salivary gland region. All concentrations increased apoptosis and injured cells (e.g., vacuolization, chromatin condensation, swelling of organelles, and plasma membrane rupture) in the principal and accessory salivary glands. Individuals that survived exposure to the highest concentrations (i.e., LC5 and LC50) were more affected, and exhibited several necrotic cells on their main principal salivary glands. Collectively, our results indicate that imidacloprid exerts toxic effects on the non-target organs, such as the salivary glands, which increases the efficacy of this compound in the management of stink bug infestations.

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The lace bug, Leptopharsa gibbicarina is a vector of Pestalotiopsis fungal complex in oil palm crops in the Americas. The effects of four benzoylphenyl ureas (BPUs) (lufenuron, novaluron, teflubenzuron, and triflumuron) were evaluated against L. gibbicarina for toxicity, survival, reproduction, and mortality in semi-field conditions. Concentration-mortality bioassays demonstrated that novaluron (LC50 = 0.33 ppm), teflubenzuron (LC50 = 0.24 ppm), lufenuron (LC50 = 0.17 ppm), and triflumuron (LC50 = 0.42 ppm) are toxic to L. gibbicarina nymphs. The survival rate was 99% in control nymphs, decreasing to 50% in nymphs exposed to LC50 of triflumuron, 47% in nymphs treated with lufenuron, 43% in nymphs treated with teflubenzuron, and 43% in those treated with novaluron. Sublethal concentrations of BPUs showed detrimental effects on the adult emergence, longevity, fecundity, and fertility of this insect. The mortality of nymphs caused by these insecticides was similar in both laboratory and semi-field conditions. Our results suggest that novaluron, teflubenzuron, and triflumuron are highly effective against L. gibbicarina, and therefore, have potential applications for this oil palm pest.

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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.

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ABSTRACT Caligo teucer (Linnaeus, 1758) is widely distributed in Argentina, Bolivia, Brazil and Ecuador. The objective was to study biological aspects of Caligo teucer japetus Stichel, 1903 with banana leaves, Musa sapientium L. (Zingiberales: Musaceae), in the butterfly garden, under environmental conditions, and in the laboratory of biological control of insects at the Universidade Federal de Viçosa in Viçosa, Minas Gerais state, Brazil at 24 ± 2 oC, 68 ± 10% relative humidity and 12 hours photophase. The duration of the egg incubation, larvae, pupa and egg to adult periods of C. teucer japetus were, respectively, 11.8 ± 0.1; 53.9 ± 0.9; 17.9 ± 0.3 and 82.6 ± 1.0 days for females, and 11.8 ± 0.1; 50.3 ± 0.6; 18.4 ± 0.3 and 79.4 ± 0.6 days for males in cages in the laboratory. The longevity of C. teucer japetus adults was 26.0 ± 10.4 and 47.5 ± 8.7 for females and 24.7 ± 3.5 and 35.4 ± 15.7 for males in the butterfly garden and in laboratory cages, respectively. The high survival and the relatively short period of development of its immature stages confirm that banana leaves are an adequate food substrate for the development and survival of Caligo teucer japetus.

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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.

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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.