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1.
J Environ Sci Health B ; 56(4): 423-430, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33678144

RESUMO

In this work, we investigated the bioactivities of the essential oil (EO) extracted from the Rhododendron thymifolium and its principal germacrone against Lasioderma serricorne and Tribolium castaneum. The EO was obtained by steam distillation. Germacrone was obtained by cryogenic crystallization. The bioactivity of EO and germacrone was tested via contact and repellent activity assays. The results showed that EO and germacrone possessed contact and repellent activities against two species of insects. EO exhibited obvious contact activity against the L. serricorn adults, larvae and T. castaneum larvae with LD50 values of 29.15 µg/adult, 42.73 µg/larva, 19.65 µg/larva respectively. Germacrone exhibited excellent contact activity against the L. serricorne adults, larvae and the T. castaneum larvae with LD50 values of 17.18 µg/adult, 20.94 µg/larva, 20.93 µg/larva respectively. And at the highest testing concentrations (78.63 and 15.73 nL/cm2), the repellent activity of EO and germacrone on two target insects was comparable to that of the positive control (DEET) after 30 h exposure. In especially, in the treatment of the 120 h after the repellent activity of EO and germacrone against T.castaneum adults and larvae were still very significant and showed the same level percentage repellency as DEET. Meanwhile, germacrone exhibited inhibition of acetylcholinesterase activity with IC50 values of 3%. The results indicated that the EO of R. thymifolium and germacrone had the potential to be developed as natural insecticides and repellents for the control of T. castaneum and L. serricorne.


Assuntos
Inibidores da Colinesterase/farmacologia , Besouros/efeitos dos fármacos , Inseticidas/farmacologia , Óleos Voláteis/farmacologia , Rhododendron/química , Animais , Inibidores da Colinesterase/química , Proteínas de Insetos/antagonistas & inibidores , Proteínas de Insetos/metabolismo , Repelentes de Insetos/química , Repelentes de Insetos/farmacologia , Inseticidas/química , Dose Letal Mediana , Óleos Voláteis/química , Sesquiterpenos de Germacrano/farmacologia , Tribolium/química , Tribolium/efeitos dos fármacos
2.
Ecotoxicol Environ Saf ; 212: 111984, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33517036

RESUMO

As a natural enemy of green peach aphids, harlequin ladybirds, Harmonia axyridis Pallas (Coleoptera: Coccinellidae), are also indirectly affected by azadirachtin. In this study, we evaluated the effects of ladybird exposure to azadirachtin through azadirachtin-treated aphids. About 2 mg/L azadirachtin treated aphid can deliver the azadirachtin to ladybird larvae in 12 and 24 h. And azadirachtin treatment affected the rate at which fourth instar larvae and adult ladybirds preyed on aphids. Furthermore, the antifeedant effect increased with increasing azadirachtin concentrations. Twelve hours after exposing fourth instar ladybird larvae to aphids treated with 10 mg/L azadirachtin, the antifeedant effect was 47.70%. Twelve hours after exposing adult ladybirds to aphids treated with 2 mg/L azadirachtin, the antifeedant effect was 67.49%. Forty-eight hours after exposing ladybird larvae to azadirachtin-treated aphids, their bodyweights were 8.37 ± 0.044 mg (2 mg/L azadirachtin), 3.70 ± 0.491 mg (10 mg/L azadirachtin), and 2.39 ± 0.129 mg (50 mg/L azadirachtin). Treatment with azadirachtin affected the ability of ladybirds to prey on aphids. The results indicated that the instant attack rate of ladybird larvae and adults and the daily maximum predation rate were reduced by azadirachtin treatment. Superoxide dismutase (SOD), peroxidase (POD), and peroxide (CAT) enzyme activities of ladybirds were affected after feeding on aphids treated with azadirachtin. Azadirachtin has certain antifeedant effects on ladybirds and affects the ability of ladybirds to prey on aphids and the activities of SOD, POD, and CAT enzymes, which results in inhibition of normal body development.


Assuntos
Afídeos/fisiologia , Besouros/enzimologia , Limoninas/toxicidade , Comportamento Predatório/efeitos dos fármacos , Animais , Besouros/efeitos dos fármacos , Besouros/crescimento & desenvolvimento , Besouros/fisiologia , Larva/crescimento & desenvolvimento , Ervilhas
3.
Ecotoxicol Environ Saf ; 208: 111597, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33396118

RESUMO

Tribolium castaneum (Herbst) is an important pest of stored grain, and benzoquinones secreted by this pest are harmful to humans. T. castaneum has developed strong resistance to fumigants, and an ecofriendly alternative for managing T. castaneum is urgently needed. 1-Octen-3-ol is a major volatile compound present in many mushrooms and fungi. In the current study, the direct toxicity and sublethal and transgenerational effects of 1-octen-3-ol on T. castaneum were investigated. Our results showed that 1-octen-3-ol had strong insecticidal activity against all developmental stages of T. castaneum and repelled T. castaneum adults. 1-Octen-3-ol showed negative effects on the development and reproduction of parental T. castaneum and the subsequent generation: LC30 and LC50 treatments significantly decreased the pupa and adult weights, pupation and emergence rates and fecundity of the parental generation. In addition, LC50 treatment shortened the larval and pupal periods. In the unexposed progeny (F1) of 1-octen-3-ol-exposed parents, decreased survival and pupation rates as well as reduced pupa and adult weights were observed under LC30 and LC50 treatments. In addition, a model food-system experiment showed that 1-octen-3-ol at 98 µL/L exhibited an efficacy of 100% after 7 days of fumigation and completely eliminated T. castaneum offspring. Although a higher concentration of 1-octen-3-ol was needed to achieve an efficacy equal to that of the positive control, dichlorvos (DDVP), 1-octen-3-ol promoted the seedling growth of wheat seeds, suggesting that the concentration used was not only acceptable but also beneficial for wheat seeds. Overall, 1-octen-3-ol seems to be a promising candidate for use as a fumigant and repellent against T. castaneum as well as a seed protectant.


Assuntos
Besouros/fisiologia , Repelentes de Insetos/toxicidade , Inseticidas/toxicidade , Octanóis/toxicidade , Tribolium/efeitos dos fármacos , Animais , Besouros/efeitos dos fármacos , Grão Comestível/efeitos dos fármacos , Fungos/efeitos dos fármacos , Humanos , Larva/efeitos dos fármacos , Pupa/efeitos dos fármacos , Triticum/efeitos dos fármacos
4.
J Agric Food Chem ; 69(5): 1455-1465, 2021 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-33497218

RESUMO

In this research, six neonicotinoid analogs derived from l-proline were synthesized, characterized, and evaluated as insecticides against Xyleborus affinis. Most of the target compounds showed good to excellent insecticidal activity. To the best of our knowledge, this is the first report dealing with the use of enantiopure l-proline to get neonicotinoids. These results highlighted the compound 9 as an excellent candidate used as the lead chiral insecticide for future development. Additionally, molecular docking with the receptor and compound 9 was carried out to gain insight into its high activity when compared to dinotefuran. Finally, the neurotoxic evaluation of compound 9 showed lower toxicity than the classic neonicotinoid dinotefuran.


Assuntos
Inseticidas/síntese química , Neonicotinoides/síntese química , Prolina/química , Animais , Besouros/efeitos dos fármacos , Besouros/crescimento & desenvolvimento , Inseticidas/química , Inseticidas/farmacologia , Simulação de Acoplamento Molecular , Estrutura Molecular , Neonicotinoides/química , Neonicotinoides/farmacologia
5.
Ecotoxicol Environ Saf ; 210: 111875, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33454577

RESUMO

Coccinella septempunctata (ladybird) is one of the foremost natural predators that feed on aphids. Thus, C. septempunctata serves as an effective biological control agent in integrated pest management (IPM) programs. To supplement the activity of biological control agents, IPM programs often incorporate chemical pesticides to bolster crop protection. To evaluate the effects of a potent insecticide, tolfenpyrad, on C. septempunctata, we tested the sublethal effects of tolfenpyrad on all developmental stages of the life cycle of C. septempunctata and its effects on the next generation. For sublethal testing of the parent generation, the LR50 of tolfenpyrad for C. septempunctata was determined to range from 1.04 to 8.43 g a.i. /hm2 within a set exposure period, while the hazard quotient (HQ) values were above our threshold value of 2 during the entire observation period. These data indicated a potential toxicity risk from tolfenpyrad exposure. The no observed effect application rates (NOERs) of tolfenpyrad on parents (F0) were determined for survival (0.485 g a.i. /hm2), developmental time of pupation (0.242 g a.i. /hm2), and fecundity (0.485 g a.i. /hm2). Application of sublethal doses to unexposed progeny (F1) of exposed parents, prolonged the L1 (1st instar of larvae) and L2 (2nd instar of larvae) stage, while the total longevity, intrinsic rate of increase (r), finite rate of increase (γ), net reproductive rate (R0), and mean generation time (T) were significantly reduced. These results demonstrated the negative influence of sublethal concentrations of tolfenpyrad on C. septempunctata and its persistent effects on subsequent generations.


Assuntos
Besouros/efeitos dos fármacos , Inseticidas/toxicidade , Pirazóis/toxicidade , Animais , Besouros/fisiologia , Feminino , Fertilidade/efeitos dos fármacos , Larva/efeitos dos fármacos , Larva/fisiologia , Estágios do Ciclo de Vida/efeitos dos fármacos , Masculino , Controle de Pragas , Reprodução/efeitos dos fármacos
6.
Gene ; 766: 145159, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-32971186

RESUMO

Considering the relevance of insect α-amylases and natural α-amylase inhibitors present in plants to protect against insect damage, we investigated the effect of white bean and rapeseed protein extracts on digestive α-amylase gene expression of the Colorado potato beetle, Leptinotarsa decemlineata (Say). For this purpose, in vitro and in vivo trials were performed to determine the inhibitory activity of seed proteins on the third and fourth instar larvae. In both trials, the significant inhibitory effect of each extracts on the third and fourth instar larval α-amylase activity and considerable mortality in treatments were observed compared to control trials. In the RT-qPCR, expression ratio demonstrated that the α-amylase gene of two different larval stages grown on both proteins treated leaves had significantly differentiated expression and was up-regulated in third instar larvae and down-regulated in fourth instar larvae compared to control. Results suggest that the hyper-production of α-amylase in third instar larvae is elicited to compensate for the enzyme activity inhibition at an earlier stage and also down-regulation suggests the existence of a negative feedback of plant proteins on the last instar larvae via impaired food intake and digestive α-amylase activity in Colorado potato beetle. Therefore, disruption of the insect's digestive physiology by plant defensive proteins can be considered in the development of innovative controlling methods of this crucial potato pest.


Assuntos
Besouros/efeitos dos fármacos , Besouros/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Larva/efeitos dos fármacos , Extratos Vegetais/farmacologia , Proteínas de Plantas/farmacologia , alfa-Amilases/genética , Animais , Digestão/efeitos dos fármacos , Digestão/genética , Regulação da Expressão Gênica/genética , Larva/genética , Folhas de Planta/química , Solanum tuberosum/parasitologia
7.
Artigo em Inglês | MEDLINE | ID: mdl-32933140

RESUMO

The present study investigates the interaction between cannabidiol (CBD) oil and three biopesticides: Azatin and two baculovirus formulations (Madex and Helicovex), both separately and in combination, in order to investigate their interaction against adults of four major coleopteran stored-product pests: Sitophilus zeamais (Coleoptera: Curculionidae), Rhyzopertha dominica (Coleoptera: Bostrichidae), Prostephanus truncatus (Coleoptera: Bostrichidae) and Trogoderma granarium (Coleoptera: Dermestidae). CBD, which has been understudied for its insecticidal properties, was applied at three different doses (500, 1500 and 3000 ppm). The biopesticides were administered at 1500 ppm. Interactions in the combined treatments were mathematically estimated as not synergistic and mostly competitive except for the combined treatments of CBD (1500 and 3000 ppm) with Azatin (1500 ppm) which were marked by an additive interaction. In its individual application, CBD oil generated the highest insect mortality while its effect was clearly dose-dependent. The findings reveal a promising effect of CBD oil against these coleopterans which had not been previously tested together.


Assuntos
Canabidiol/toxicidade , Besouros/efeitos dos fármacos , Inseticidas/toxicidade , Praguicidas/toxicidade , Gorgulhos/efeitos dos fármacos , Animais , Dominica
8.
Ecotoxicol Environ Saf ; 203: 110998, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32778532

RESUMO

Relative ecotoxicity of approved neonicotinoids (i.e. imidacloprid, clothianidin, acetamiprid, thiacloprid, thiamethoxam and dinotefuran) and diamides (i.e. chlorantraniliprole, cyantraniliprole and flubendiamide) was examined on population growth parameters of Zygogramma bicolorata Pallister on parthenium under laboratory conditions at 27 ± 1 °C, 65 ± 5% relative humidity and 10 L : 14D photoperiod. The dose of all tested insecticides in the bioassay procedure was within a minimum range of their recommended field rate. In acute toxicity trial, imidacloprid caused highest rate of mortality in treated adults of Z. bicolorata, however, it was lowest in flubendiamide treatment followed by cyantraniliprole and chlorantraniliprole. Further, based on toxicity coefficient (E) value in acute toxicity trial, all were classified as harmful (H) and diamides were classified as moderately harmful (MH) as per IOBC classification. Moreover, chronic toxicity trials were carried out through life table response experiments (LTREs) in the F1 progeny of acute toxicity experienced group. Prolonged development with the highest mortality was evident in as compared to diamides. Furthermore, population growth parameters i.e. potential fecundity (Pf), natality rate (mx), intrinsic rate of increase (rm), net reproductive rate (R0) and finite rate of increase (λ) was greatly reduced in Z. bicolorata treated with neonicotinoids as compared with diamides. However, mean generation time (Tc), corrected generation time (τ) and the doubling time (DT) was prolonged in neonicotinoids followed by diamides. Furthermore, proportion of females was greatly reduced (0.43-0.48 females) in neonicotinoids as comparison to diamides (0.53-0.55 females) and control (0.67 females). On the basis of ecotoxicity trials, the tested neonicotinoids were highly toxic to Z. bicolorata than diamides. Therefore, diamide insecticides could be used with Z. bicolorata, however, for validation experimentation need to be done under natural field conditions.


Assuntos
Besouros/efeitos dos fármacos , Diamida/toxicidade , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Animais , Besouros/fisiologia , Ecotoxicologia , Feminino , Crescimento Demográfico , Testes de Toxicidade Aguda
9.
PLoS One ; 15(7): e0236276, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32730348

RESUMO

Red turpentine beetle, Dendroctonus valens (Coleoptera: Curculionidae: Scolytinae) is a non-aggressive pine bark beetle native to North America, and more aggressive invader in China. Dispersing pioneer beetles are attracted to potential host trees by oleoresin monoterpene kairomones, but respond more strongly to those combined with ethanol, a mixture often released from stressed, dying, or recently dead trees. (+)-3-Carene, usually the dominant or co-dominant monoterpene in ponderosa pine, Pinus ponderosa, is a stronger attractant than α-pinene or ß-pinene where tested over a large portion of the D. valens range, while (+)-3-carene+ethanol was shown previously to attract twice the beetles of (+)-3-carene. A field test comparing D. valens attraction among the three monoterpenes when all are released with ethanol has never been reported, and was our objective. In three US Pacific Northwestern pine forests, (-)-ß-pinene+ethanol lures attracted 1.4 to 1.9 times more beetles than (+)-3-carene+ethanol. (+)- or (±)-α-pinene+ethanol lures were least attractive. A 1:1:1 monoterpene mixture+ethanol lure attracted more beetles than the 1:1:1 lure, but it was not statistically higher. Monoterpenes were dispensed from low density polyethylene bottles and their release rates monitored in laboratory and field tests. Under laboratory conditions (+)-3-carene was released much more rapidly than (+)-α-pinene or (-)-ß-pinene when dispensed separately, or in a 1:1:1 mixture. (+)-3-Carene in the 1:1:1 mixture increased the release of both pinenes over their rates when dispensed separately. (-)-ß-Pinene+ethanol is currently the strongest kairomone lure for D. valens attraction in US northwest pine forests, and has value for beetle detection, monitoring, research, and management.


Assuntos
Monoterpenos Bicíclicos/farmacologia , Besouros/fisiologia , Etanol/farmacologia , Florestas , Terebintina/farmacologia , Animais , Monoterpenos Bicíclicos/química , Besouros/efeitos dos fármacos , Geografia , Laboratórios , Noroeste dos Estados Unidos , Polietileno/química , Temperatura , Volatilização
10.
Chemosphere ; 259: 127497, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32650168

RESUMO

Heavy metal pollution is an increasingly serious problem in agricultural ecosystems. Zinc accumulation in the food chain may harm the physiological functions of organisms, including herbivorous and predatory insects. Its effects on development and reproduction in Harmonia axyridis are largely unknown. In this study, five Zn solutions (25, 50, 100, and 150 mg/kg) plus control (0 mg/kg) were used to treat broad beans and to water the resulting seedlings. Aphids fed on these seedlings were eaten by H. axyridis ladybugs. Zn accumulation was found at all three trophic levels. Compared with the control group, ladybugs in the 25, 50, and 100 mg/kg groups had significantly reduced weight gain from the 4th instar to adulthood. Pupae and larvae (instars 1-4) in the 150 mg/kg group had the lowest survival of any group; pupal mortality in the 100 mg/kg group was significantly higher than that in the control group. Under Zn stress, female adults had inhibited expression of Vg1, Vg2 and VgR, reducing egg production and hatchability. Zn thus negatively affected their fertility. These results provide a theoretical basis for future exploration of soil heavy metal pollution impacts in ecosystems.


Assuntos
Afídeos/química , Besouros/efeitos dos fármacos , Poluentes Ambientais/farmacologia , Fertilidade/efeitos dos fármacos , Cadeia Alimentar , Zinco/farmacologia , Animais , Afídeos/metabolismo , Besouros/crescimento & desenvolvimento , Besouros/metabolismo , Besouros/fisiologia , Relação Dose-Resposta a Droga , Poluentes Ambientais/metabolismo , Feminino , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Masculino , Metais Pesados/metabolismo , Metais Pesados/farmacologia , Plantas Comestíveis/química , Plantas Comestíveis/parasitologia , Reprodução/efeitos dos fármacos , Zinco/metabolismo
11.
Proc Natl Acad Sci U S A ; 117(31): 18385-18392, 2020 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-32690686

RESUMO

Transgenic crops that produce insecticidal proteins from Bacillus thuringiensis (Bt) can suppress pests and reduce insecticide sprays, but their efficacy is reduced when pests evolve resistance. Although farmers plant refuges of non-Bt host plants to delay pest resistance, this tactic has not been sufficient against the western corn rootworm, Diabrotica virgifera virgifera In the United States, some populations of this devastating pest have rapidly evolved practical resistance to Cry3 toxins and Cry34/35Ab, the only Bt toxins in commercially available corn that kill rootworms. Here, we analyzed data from 2011 to 2016 on Bt corn fields producing Cry3Bb alone that were severely damaged by this pest in 25 crop-reporting districts of Illinois, Iowa, and Minnesota. The annual mean frequency of these problem fields was 29 fields (range 7 to 70) per million acres of Cry3Bb corn in 2011 to 2013, with a cost of $163 to $227 per damaged acre. The frequency of problem fields declined by 92% in 2014 to 2016 relative to 2011 to 2013 and was negatively associated with rotation of corn with soybean. The effectiveness of corn rotation for mitigating Bt resistance problems did not differ significantly between crop-reporting districts with versus without prevalent rotation-resistant rootworm populations. In some analyses, the frequency of problem fields was positively associated with planting of Cry3 corn and negatively associated with planting of Bt corn producing both a Cry3 toxin and Cry34/35Ab. The results highlight the central role of crop rotation for mitigating impacts of D. v. virgifera resistance to Bt corn.


Assuntos
Besouros/fisiologia , Produção Agrícola/métodos , Endotoxinas/farmacologia , Doenças das Plantas/parasitologia , Plantas Geneticamente Modificadas/imunologia , Zea mays/imunologia , Animais , Bacillus thuringiensis/genética , Bacillus thuringiensis/metabolismo , Besouros/efeitos dos fármacos , Produção Agrícola/economia , Endotoxinas/genética , Endotoxinas/metabolismo , Resistência a Inseticidas , Iowa , Controle Biológico de Vetores/economia , Doenças das Plantas/economia , Doenças das Plantas/imunologia , Doenças das Plantas/prevenção & controle , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/parasitologia , Soja/crescimento & desenvolvimento , Zea mays/genética , Zea mays/crescimento & desenvolvimento , Zea mays/parasitologia
12.
Chemosphere ; 258: 127254, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32559492

RESUMO

Glyphosate is the most used herbicide worldwide, targeting physiological pathways in plants. Recent studies have shown that glyphosate can also cause toxic effects in animals. We investigated the glyphosate-based herbicide (GBH)-induced changes in potato (Solanum tuberosum) plant chemistry and the effects of a GBH on the survival rate and oxidative status of the Colorado potato beetle (Leptinotarsa decemlineata). The beetles were reared on potato plants grown in pots containing soil treated with a GBH (Roundup Gold, 450 g/l) or untreated soil (water control). The 2nd instar larvae were introduced to the potato plants and then collected in 2 phases: as 4th instar larvae and as adults. The main glycoalkaloids of the potato plants, α-solanine and α-chaconine, were measured twice during the experiment. The α-solanine was reduced in potato plants grown in GBH-treated soil, which can be detrimental to plant defenses against herbivores. GBH treatment had no effect on the survival rate or body mass of the larvae or the adult beetles. In the larvae, total glutathione (tGSH) concentration and the enzyme activity of catalase (CAT), superoxide dismutase, and glutathione-S-transferase were increased in the GBH treatment group. In the adult beetles, CAT activity and tGSH levels were affected by the interactive effect of GBH treatment and the body mass. To conclude, environmentally relevant concentrations of a GBH can affect the potato plant's glycoalkaloid concentrations, but are not likely to directly affect the survival rate of the Colorado potato beetle, but instead, modify the antioxidant defense of the beetles via diet.


Assuntos
Besouros/efeitos dos fármacos , Glicina/análogos & derivados , Herbicidas/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Solo/química , Solanum tuberosum/efeitos dos fármacos , Animais , Antioxidantes/metabolismo , Besouros/metabolismo , Glutationa Transferase/metabolismo , Glicina/toxicidade , Larva/efeitos dos fármacos , Larva/metabolismo , Oxirredução , Solanina/análogos & derivados , Solanina/metabolismo , Solanum tuberosum/crescimento & desenvolvimento , Solanum tuberosum/metabolismo
13.
Arch Insect Biochem Physiol ; 104(4): e21685, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32350927

RESUMO

The Colorado potato beetle (CPB; Leptinotarsa decemlineata) is one of the most notorious and difficult to control pests of potato and other solanaceous crops in North America. This insect has evolved a remarkable ability to detoxify both plant and synthetic toxins, allowing it to feed on solanaceous plants containing toxic alkaloids and to develop resistance to synthetic chemicals used for its control. RNA interference (RNAi) is a natural mechanism that evolved as an immune response to double-stranded RNA (dsRNA) viruses where dsRNA triggers silencing of target gene expression. RNAi is being developed as a method to control CPB. Here, we evaluated four CPB-specific genes to identify targets for RNAi-mediated control of this insect. Out of the four dsRNAs evaluated in CPB larvae and adults, dsIAP (dsRNA targeting inhibitor of apoptosis, iap gene) performed better than dsActin, dsHSP70, and dsDynamin in inducing larval mortality. However, in adults, the mortality induced by dsActin is significantly higher than the mortality induced by dsIAP, dsHSP70, and dsDynamin. Interestingly, a combination of dsIAP and dsActin performed better than either dsIAP or dsActin alone by inducing feeding inhibition in 24 hr and mortality in 48 hr in larvae. When the dsIAP and dsActin were expressed in the Escherichia coli HT115 strain and applied as a heat-killed bacterial spray on potato plants, it protected the plants from CPB damage. These studies show that the combination of dsIAP and dsActin shows promise as an insecticide to control CPB.


Assuntos
Besouros/genética , Proteínas Inibidoras de Apoptose/genética , Interferência de RNA , Actinas/genética , Animais , Besouros/efeitos dos fármacos , Besouros/crescimento & desenvolvimento , Escherichia coli , Controle de Insetos/métodos , Proteínas de Insetos/genética , Larva/efeitos dos fármacos , RNA de Cadeia Dupla , Solanum tuberosum
14.
Chemosphere ; 256: 126986, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32445995

RESUMO

Systemic neurotoxic insecticides are widely used to control aphid pests worldwide and their potential non-target effects on aphid predators are often unknown. Behavioral responses linked to biological control services are crucial when assessing the compatibility of chemicals with biocontrol organisms. This is particularly relevant for insecticides at low and sublethal concentrations. We studied the acute toxicity and the sublethal effect on the voracity of the generalist predator Harmonia axyridis (Coleoptera: Coccinellidae) caused by the exposure to three systemic insecticides routinely used against aphids. The tested insecticide concentrations were the Lethal Concentration 50% (LC50), 20% (LC20) and 1% (LC1) estimated for the target pest Aphis gossypii (Hemiptera: Aphididae) in a companion study. The survival and the voracity differed among the tested chemicals and concentrations, but only thiamethoxam at LC50 caused a significant predator mortality, and individuals that survived showed a reduced predation rate. The predators showed a density independent functional response after the exposure to most of the insecticide-concentration combinations, while an inverse density dependence of the prey consumption rate was observed for coccinellids exposed to sulfoxaflor and thiamethoxam at their lowest tested concentration. The estimated parameters, i.e., the attack rate and the prey handling time, were affected at higher concentrations by both imidacloprid and sulfoxaflor. These findings stress the importance of carefully evaluating side effects of insecticides at very low concentrations on beneficial arthropods in the risk assessment schemes for sustainable pest control programmes.


Assuntos
Afídeos/efeitos dos fármacos , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Nitrocompostos/toxicidade , Animais , Afídeos/fisiologia , Besouros/efeitos dos fármacos , Dose Letal Mediana , Comportamento Predatório/efeitos dos fármacos , Piridinas , Compostos de Enxofre , Tiametoxam
15.
Poult Sci ; 99(4): 2120-2124, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32241497

RESUMO

Poultry litter reuse in Brazil is a common practice to reduce broiler production costs. Quicklime and shallow fermentation treatments are methods used to reduce microbial contamination and infestation of insects such as Alphitobius diaperinus (Panzer). The aim of this study was to evaluate the physicochemical parameters of reused poultry litter to better characterize the effects of quicklime and shallow fermentation on Salmonella and A. diaperinus control. Ammonia and humidity concentrations significantly increased on the litter treated with shallow fermentation and pH when treated with virgin and hydrated quicklime. For A. diaperinus control, shallow fermentation with 2 and 3 L of water and 3 L plus 600g of quicklime/m2 eliminated 100% of the insects. Results of assessed physicochemical parameters indicated that the treatments with quicklime and shallow fermentation are inefficient to control Salmonella spp. because they do not reach the indexes required for this pathogen elimination, mainly ammonia and pH. Ammonia index produced by microbial fermentation in shallow fermentation treatment eliminates A. diaperinus.


Assuntos
Antibacterianos/farmacologia , Compostos de Cálcio/farmacologia , Besouros/efeitos dos fármacos , Controle de Insetos , Óxidos/farmacologia , Doenças das Aves Domésticas/prevenção & controle , Salmonelose Animal/prevenção & controle , Animais , Antibacterianos/administração & dosagem , Brasil , Compostos de Cálcio/administração & dosagem , Controle de Doenças Transmissíveis/métodos , Fermentação , Abrigo para Animais , Óxidos/administração & dosagem , Salmonella/efeitos dos fármacos
16.
Environ Toxicol Chem ; 39(4): 863-872, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32181912

RESUMO

It is often difficult to compare studies examining the effects of endectocides on dung fauna because of different experimental approaches, for example, active ingredients (eprinomectin, doramectin, ivermectin, moxidectin) and formulations (injectable, pour-on, spiked). To gain a better understanding, we performed a quantitative meta-analysis using 22 studies to assess the overall effect of endectocide residues on the occurrence (presence or absence) and abundance of aphodiine dung beetles. Our results document a positive effect on the occurrence of adult beetles, indicating that adults tend to be attracted to dung with residues. Conversely, larvae are less likely to occur in the presence of residues. Thus, either adults that colonize dung with residues do not lay eggs or, more likely, the larvae that hatch from these eggs die early in development. Abundance of adult and larval stages was shown to be significantly reduced in dung containing residues. When individual endectocides were compared, only ivermectin demonstrated a significantly negative effect on the abundance of both adults and larvae, possibly owing to a small sample size for other agents. In laboratory studies, only dung "spiked" with endectocides reduced the abundance of larvae, whereas during field research, only pour-on applications were shown to reduce the abundance of larvae. The present study further documents the nontarget effects of endectocide residues on dung-dwelling organisms, provides robust evidence on the consequences of different application methods, and emphasizes the need for standardized methodological techniques in future studies. Environ Toxicol Chem 2020;39:863-872. © 2020 SETAC.


Assuntos
Besouros/efeitos dos fármacos , Resíduos de Drogas/toxicidade , Poluentes Ambientais/toxicidade , Ivermectina/análogos & derivados , Drogas Veterinárias/toxicidade , Animais , Besouros/crescimento & desenvolvimento , Resíduos de Drogas/análise , Poluentes Ambientais/análise , Fezes/química , Ivermectina/análise , Ivermectina/toxicidade , Larva/efeitos dos fármacos , Gado , Drogas Veterinárias/análise
17.
BMC Genomics ; 21(1): 154, 2020 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-32050907

RESUMO

BACKGROUND: The small hive beetle, Aethina tumida, is a rapidly emerging global pest of honey bee colonies. Small hive beetle infestation can be extremely destructive, which may cause honey bees to abscond and render colony infrastructure unusable. Due to the impacts small hive beetles have on honey bees, a wide variety of physical, cultural, and chemical control measures have been implemented to manage small hive beetle infestations. The use of insecticides to control small hive beetle populations is an emerging management tactic. Currently, very little genomic information exists on insecticide target sites in the small hive beetle. Therefore, the objective of this study is to utilize focused in silico comparative genomics approaches to identify and assess the potential insecticide sensitivity of the major insecticide target sites in the small hive beetle genome. RESULTS: No previously described resistance mutations were identified in any orthologs of insecticide target sites. Alternative exon use and A-to-I RNA editing were absent in AtumSC1. The ryanodine receptor in small hive beetle (Atum_Ryr) was highly conserved and no previously described resistance mutations were identified. A total of 12 nAChR subunits were identified with similar alternative exon use in other insects. Alternative exon use and critical structural features of the GABA-gated chloride channel subunits (Atum_RDL, Atum_GRD, and Atum_LCCH3) were conserved. Five splice variants were found for the glutamate-gated chloride channel subunit. Exon 3c of Atum_GluCl may be a beetle-specific alternative exon. The co-occurrence of exons 9a and 9b in the pH-sensitive chloride channel (Atum_pHCl) is a unique combination that introduces sites of post-translational modification. The repertoire and alternative exon use for histamine-gated chloride channels (Atum-HisCl), octopamine (Atum_OctR) and tyramine receptors (Atum_TAR) were conserved. CONCLUSIONS: The recently published small hive beetle genome likely serves as a reference for insecticide-susceptible versions of insecticide target sites. These comparative in silico studies are the first step in discovering targets that can be exploited for small hive beetle-specific control as well as tracking changes in the frequency of resistance alleles as part of a resistance monitoring program. Comparative toxicity alongside honey bees is required to verify these in silico predictions.


Assuntos
Besouros/efeitos dos fármacos , Besouros/genética , Biologia Computacional , Regulação da Expressão Gênica/efeitos dos fármacos , Genes de Insetos , Genoma de Inseto , Inseticidas/farmacologia , Animais , Biomarcadores , Besouros/classificação , Biologia Computacional/métodos , Concentração de Íons de Hidrogênio , Controle de Insetos , Ligantes , Anotação de Sequência Molecular , Filogenia
18.
PLoS One ; 15(2): e0228817, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32032382

RESUMO

Abamectin is a common biocide used to control agricultural insect pests. However, the water insolubility of abamectin may result in extra organic solvent introduced in the environment. To solve this issue, it is desirable to develop nanoformulations to encapsulate abamectin with environment-friendly polymers. In this study, two polylactic acid based abamectin nanoformulations were prepared. The average particle sizes, measured by dynamic light scattering and transmission electron microscope, were 240 nm and 150 nm, respectively. The insecticidal activity of these nano-formulated abamectin was examined in the laboratory on the pea aphid, Acyrthosiphon pisum (Hemiptera: Aphididae). The acute toxicity of nano-formulated abamectin on non-target aphid predator Adalia bipunctata (Coleoptera: Coccinellidae) was also evaluated by topical, residual and oral exposure. The two nano-formulated abamectin had comparable insecticidal effect with commercial abamectin formulation against the pea aphid. Taking median lethal concentration (LC50) as the toxicological endpoint, nanoformulations had higher contact toxicity and lower oral toxicity to first-instar larvae of the predator A. bipunctata. These results are expected to contribute to the application of solvent-free nano-formulated pesticides that comply with the integrated pest management (IPM) strategies.


Assuntos
Afídeos/efeitos dos fármacos , Besouros/efeitos dos fármacos , Inseticidas/toxicidade , Ivermectina/análogos & derivados , Nanoestruturas/química , Poliésteres/química , Animais , Afídeos/crescimento & desenvolvimento , Besouros/crescimento & desenvolvimento , Composição de Medicamentos , Inseticidas/química , Ivermectina/química , Ivermectina/toxicidade , Dose Letal Mediana , Tamanho da Partícula
19.
Ecotoxicol Environ Saf ; 192: 110292, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32035396

RESUMO

The ladybeetle Propylea japonica is a widely distributed natural enemy in many agricultural systems. P. japonica is often used as a test organism for safety assessments of transgenic Bacillus thuringiensis crops. Plant varieties expressing the Vip3Aa insecticidal protein are not currently commercially available in China. In this study, protease inhibitor E-64 was used as a positive control to examine the responses of P. japonica larvae to a high concentration of Vip3Aa proteins. Larvae that were fed E-64 had increased mortality and prolonged developmental period, but these parameters were unaffected when larvae were fed Vip3Aa. The epithelial cells of midguts were intact and closely connected with the basal membrane when larvae were fed Vip3Aa, but the epithelial cells degenerated in the E-64 treatment. The activities of antioxidative enzymes and expression levels of detoxification-related genes in P. japonica larvae were not altered after exposure to Vip3Aa; however, these biochemical and molecular parameters were significantly changed in the E-64 treatment. The results demonstrate that Vip3Aa protein is not harmful to the predator P. japonica.


Assuntos
Proteínas de Bactérias/toxicidade , Besouros/efeitos dos fármacos , Inseticidas/toxicidade , Animais , China , Besouros/genética , Besouros/metabolismo , Larva/efeitos dos fármacos , Larva/enzimologia , Larva/genética , Larva/metabolismo
20.
Sci Rep ; 10(1): 3444, 2020 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-32103102

RESUMO

Storing grains remain vulnerable to insect pest attack. The present study developed a biopesticide using biomolecules and their encapsulation in nanoparticles. A 25 kDa cysteine protease extracted from seeds of Albizia procera (ApCP) was encapsulated in graphene quantum dots (GQDs). The insecticidal activity of ApCP, with or without GQDs, against two stored grain insect pests, Tribolium castaneum (Herbst) and Rhyzopertha dominica (Fabricius) was explored. Insects were exposed to three concentrations 7.0, 3.5 and 1.7 mg of ApCP per a gram of wheat flour and grains. The insecticidal activity of ApCP encapsulated with GQDs was improved compared to that of ApCP without GQDs for both insect pests. The number of eggs and larvae of T. castaneum was reduced by 49% and 86%, respectively. Larval mortality was increased to 72%, and adult eclosion of T. castaneum was reduced by 98% at a 7.0 mg/g concentration of ApCP with GQDs compared to that of ApCP without GQDs. Exposure to 7.0 mg/g ApCP with GQDs, the number of R. dominica eggs and larvae was reduced by 72% and 92% respectively, larval mortality was increased by 90%, and eclosion was reduced by 97%. The extraction, purification, characterization, quantification and encapsulation of ApCP with GQDs were also studied. Cysteine protease nanocarriers have the potential to control stored grain insect pests.


Assuntos
Besouros/efeitos dos fármacos , Cisteína Proteases/farmacologia , Grafite/química , Pontos Quânticos/química , Albizzia/enzimologia , Albizzia/crescimento & desenvolvimento , Sequência de Aminoácidos , Animais , Besouros/crescimento & desenvolvimento , Cisteína Proteases/química , Cisteína Proteases/isolamento & purificação , Controle de Insetos , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Pontos Quânticos/toxicidade , Sementes/enzimologia , Alinhamento de Sequência , Tribolium/efeitos dos fármacos , Tribolium/crescimento & desenvolvimento
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