RESUMO
Insecticidal gene silencing by RNA interference (RNAi) involves a post-transcriptional mechanism with great potential for insect control. Here, we aim to summarize the progress on RNAi research toward control of insect pests in the Neotropical region and discuss factors determining its efficacy and prospects for pest management. We include an overview of the available RNAi information for Neotropical pests in the Lepidoptera, Coleoptera, Diptera, and Hemiptera orders. Emphasis is put on significant findings in the use of RNAi against relevant Neotropical pests, including diamondback moth (Plutella xylostella L.), Asian citrus psyllid (Diaphorina citri Kuwayama), and the cotton boll weevil (Anthonomus grandis Boheman). We also examine the main factors involved in insecticidal RNAi efficiency and major advances to improve screening of lethal genes, formulation, and delivery. Few studies detail resistance mechanisms to RNAi, demonstrating a need for more research. Advances in formulation, delivery, and resistance management tools for insecticidal RNAi in the Neotropics can provide a basis for efficient field application.
Assuntos
Hemípteros/genética , Controle de Insetos/métodos , Mariposas/genética , Interferência de RNA , Gorgulhos/genética , Animais , América Central , Genes Letais , América do Sul , Clima TropicalRESUMO
Use of pesticides in agroecosystems is considered a major cause of bees diversity losses in the Neotropics, where Plebeia emerina (Friese) and Tetragonisca fiebrigi (Schwarz) (Hymenoptera: Apidae: Meliponini) are wild pollinators of native and crop plants. The aim of this study was to know the acute lethal toxicity of acetamiprid, malathion, phosmet and spinosad insecticides on P. emerina and T. fiebrigi. We obtained the mean concentration and mean lethal dose (LC50 and LD50) and the mean survival of workers after oral and topical exposure to insecticides, respectively. The LC50 values (ng a.i./µl of diet) and the decreasing order of toxicity for P. emerina was spinosad (4.96) > malathion (18.75) > phosmet (97.33) > acetamiprid (4204.06), and for T. fiebrigi also was spinosad (5.65) > malathion (8.39) > phosmet (53.91) > acetamiprid (9841.32), when orally exposed. The LD50 values (ng a.i./bee) and the decreasing order of toxicity for P. emerina was spinosad (1.90) > malathion (10.90) > phosmet (19.54) > acetamiprid (6216.55) and for T. fiebrigi was malathion (29.29) ≥ spinosad (29.79) > phosmet (41.95) > acetamiprid (1421.23), when topically exposed. The mean survival (hours) of contaminated bees by malathion, phosmet, and spinosad, was 11.81, 7.20, and 12.32 for P. emerina and 8.55, 7.20, and 13.34 for T. fiebrigi when orally exposed; and was 4.87, 9.87 and 11.17 for P. emerina, and 4.87, 4.76, and 19.05 for T. fiebrigi when topically exposed. Malathion, phosmet, and spinosad were highly toxic, while acetamiprid was moderately toxic. Our results indicated that the insecticides tested, mainly malathion, phosmet, and spinosad may be harmful to P. emerina and T. fiebrigi, making it essential to propose measures to minimize their impact on wild pollinators.
Assuntos
Abelhas/fisiologia , Himenópteros/fisiologia , Inseticidas/toxicidade , Animais , Abelhas/efeitos dos fármacos , Combinação de Medicamentos , Himenópteros/efeitos dos fármacos , Dose Letal Mediana , Macrolídeos , Malation , Neonicotinoides , PolinizaçãoRESUMO
The time has passed for us to wonder whether RNA interference (RNAi) effectively controls pest insects or protects beneficial insects from diseases. The RNAi era in insect science began with studies of gene function and genetics that paved the way for the development of novel and highly specific approaches for the management of pest insects and, more recently, for the treatment and prevention of diseases in beneficial insects. The slight differences in components of RNAi pathways are sufficient to provide a high degree of variation in responsiveness among insects. The current framework to assess the negative effects of genetically modified (GM) plants on human health is adequate for RNAi-based GM plants. Because of the mode of action of RNAi and the lack of genomic data for most exposed non-target organisms, it becomes difficult to determine the environmental risks posed by RNAi-based technologies and the benefits provided for the protection of crops. A better understanding of the mechanisms that determine the variability in the sensitivity of insects would accelerate the worldwide release of commercial RNAi-based approaches.
Assuntos
Controle de Insetos/métodos , Insetos/genética , Controle Biológico de Vetores/métodos , Interferência de RNA , Doenças dos Animais/prevenção & controle , Animais , Meio Ambiente , MicroRNAs/fisiologia , RNA Interferente Pequeno/fisiologia , Medição de Risco , VirosesRESUMO
O objetivo do presente trabalho foi avaliar a seletividade dos inseticidas utilizados na cultura do milho sobre Doru lineare. Foi avaliada a seletividade de inseticidas utilizados na cultura do milho para D. lineare, seguindo metodologia proposta pela IOBC/WPRS em condições de laboratório. Adultos foram expostos aos resíduos dos inseticidas por meio de contato com placas de vidros e pelo consumo de ovos de Spodoptera frugiperda contaminados com os inseticidas. A porcentagem de mortalidade dos insetos em contato residual foi utilizada para classificar os inseticidas como inócuo (< 30%), levemente nocivo (30-79%), moderadamente nocivo (80-99%) e nocivo (> 99%). A mortalidade de adultos após consumo de ovos contaminados foi comparada com a testemunha. Para adultos deD. lineare mediante contato residual, nas 360 HAIE (horas após o início da exposição), os inseticidas Decis 25 EC, Dimilin, Engeo Pleno, Karate Zeon 250 CS, Lorsban 480 BR, Match EC, Neem Azal e Sevin 480 SC foram nocivos ao predador. Certero, Fastac 100 SC e Tracer foram moderadamente nocivos. Intrepid 240 SC e Mimic 240 SC foram inócuos. A mortalidade de adultos após o consumo de ovos contaminados foi significativa para os inseticidas Certero, Dimilin, Tracer, Engeo Pleno, Lorsban 480 BR, Sevin 480 SC.
The objective of this work was to evaluate the selectivity of insecticides used in the corn crop to Doru lineare (Eschscholtz, 1822) (Dermaptera: Forficulidae), following methodology suggested by IOBC/WPRS, under laboratory conditions. Adult insects were placed on glass plates or fed on Spodoptera frugiperda eggs, both containing previously sprayed insecticide residues. The adult mortality by the residual contact was used to classify insecticides as harmless (< 30%), slightly harmful (30-79%), moderately harmful (80-99%) and harmful (> 99%). The adult mortality due to consumption of the contaminated eggs was compared to the control. For adults ofD. linearein residual contact after 360 HASE (hours after start of exposure) the insecticides Decis 25 EC, Dimilin, Engeo Pleno, Karate Zeon 250 CS, Lorsban 480 BR, Match EC, Neem Azal and Sevin 480 SC were harmful. Certero, Fastac 100 SC and Tracer were moderately harmful. Intrepid 240 SC and Mimic 240 SC were slightly harmful. The mortality of adults after consumption of contaminated eggs was noteworthy for the insecticides Certero, Dimilin, Tracer, Engeo Pleno, Lorsban 480 BR and Sevin 480 SC.
Assuntos
Controle de Insetos/métodos , Zea mays/parasitologia , Neópteros , Inseticidas/administração & dosagem , Pragas da AgriculturaRESUMO
O objetivo do trabalho foi avaliar a seletividade de inseticidas usados na cultura do milho para o controle de Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) sobre ninfas de primeiro ínstar e ovos do predador Doru lineare (Scudder, 1876) (Dermaptera: Forficulidae). Para os bioensaios foi utilizada a metodologia padronizada da IOBC/WPRS, em condições de laboratório, com temperatura de 25 ± 1º C, umidade relativa de 70 ± 10% e fotofase de 14 horas. No bioensaio com ninfas para contato residual, a aplicação dos inseticidas foi realizada com um equipamento pressurizado a CO2, pressão de 50 psi. Para aplicação dos inseticidas sobre os ovos foi utilizada torre de Potter, com pressão de 10 psi. Em ambas as formas de aplicação o depósito foi de 1,75 ± 0,25 mg de calda cm-2 conforme metodologia da IOBC/WPRS. A mortalidade de ninfas foi utilizada para classificar os inseticidas como inócuo (< 30%), levemente nocivo (30-79%), moderadamente nocivo (80-99%) e nocivo (> 99%). Os dados de viabilidade de ovos e sobrevivência de ninfas que eclodiram deles foram comparados com os dados das testemunhas positiva (Sevin 480 SC) e negativa (água). Certero, Dimilin, Engeo Pleno, Karate Zeon 250 SC, Lorsban 480 BR, Match EC e Sevin 480 SC reduziram a viabilidade de ovos. A sobrevivência de ninfas provenientes dos ovos tratados teve redução para os inseticidas: Decis 25 EC, Dimilin, Engeo Pleno, Karate Zeon 250 CS, Lorsban 480 BR e Sevin 480 SC. Para ninfas de D. lineare em contato residual, todos os inseticidas foram nocivos em 96 horas após a exposição.
The goal of this work was to evaluate the selectivity of insecticides used in corn crops for the control of Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) on first-instar nymphs and eggs of the earwig Doru lineare. For the bioassays the standardized methodology of IOBC/WPRS was used in terms of temperature (25 ± 1º C), relative humidity (70 ± 15%) and photophase (14 hours). In the bioassay with nymphs for residual contact, the applications of insecticides was conducted with equipment pressurized by CO2 to 50 psi. For applications of insecticides on eggs, a Potter's tower was used, with pressure of 10 psi. In both forms of spraying the deposit was 1.75±0.25 mg cm-2 of aqueous solution in accordance with the IOBC/WPRS methodology. The mortality of nymphs was used to classify insecticides as harmless (< 30%), slightly harmful (30-79%), moderately harmful (80-99%) and harmful (> 99%). Viability of eggs and survival of hatched nymphs were both evaluated by comparing with the positive (Sevin 480 SC) and negative (water) controls. The viability of eggs was reduced by Certero, Dimilin, Engeo Pleno, Karate Zeon 250 SC, Lorsban 480 BR, Match EC and Sevin 480 SC. The survival of nymphs from treated eggs was reduced by the insecticides Decis EC, Dimilin, Engeo Pleno, Karate Zeon 250 CS, Lorsban 480 BR and Sevin 480 SC. For nymphs of D. lineare in residual contact, all the insecticides were harmful.
Assuntos
Controle de Insetos/métodos , Zea mays/parasitologia , Inseticidas/administração & dosagem , Insetos/parasitologiaRESUMO
ABSTRACT The objective of this work was to evaluate the selectivity of insecticides used in the corn crop to Doru lineare (Eschscholtz, 1822) (Dermaptera: Forficulidae), following methodology suggested by IOBC/WPRS, under laboratory conditions. Adult insects were placed on glass plates or fed on Spodoptera frugiperda eggs, both containing previously sprayed insecticide residues. The adult mortality by the residual contact was used to classify insecticides as harmless ( 30%), slightly harmful (30-79%), moderately harmful (80-99%) and harmful (> 99%). The adult mortality due to consumption of the contaminated eggs was compared to the control. For adults ofD. linearein residual contact after 360 HASE (hours after start of exposure) the insecticides Decis 25 EC, Dimilin, Engeo Pleno, Karate Zeon 250 CS, Lorsban 480 BR, Match EC, Neem Azal and Sevin 480 SC were harmful. Certero, Fastac 100 SC and Tracer were moderately harmful. Intrepid 240 SC and Mimic 240 SC were slightly harmful. The mortality of adults after consumption of contaminated eggs was noteworthy for the insecticides Certero, Dimilin, Tracer, Engeo Pleno, Lorsban 480 BR and Sevin 480 SC.
RESUMO O objetivo do presente trabalho foi avaliar a seletividade dos inseticidas utilizados na cultura do milho sobre Doru lineare. Foi avaliada a seletividade de inseticidas utilizados na cultura do milho para D. lineare, seguindo metodologia proposta pela IOBC/WPRS em condições de laboratório. Adultos foram expostos aos resíduos dos inseticidas por meio de contato com placas de vidros e pelo consumo de ovos de Spodoptera frugiperda contaminados com os inseticidas. A porcentagem de mortalidade dos insetos em contato residual foi utilizada para classificar os inseticidas como inócuo ( 30%), levemente nocivo (30-79%), moderadamente nocivo (80-99%) e nocivo (> 99%). A mortalidade de adultos após consumo de ovos contaminados foi comparada com a testemunha. Para adultos deD. lineare mediante contato residual, nas 360 HAIE (horas após o início da exposição), os inseticidas Decis 25 EC, Dimilin, Engeo Pleno, Karate Zeon 250 CS, Lorsban 480 BR, Match EC, Neem Azal e Sevin 480 SC foram nocivos ao predador. Certero, Fastac 100 SC e Tracer foram moderadamente nocivos. Intrepid 240 SC e Mimic 240 SC foram inócuos. A mortalidade de adultos após o consumo de ovos contaminados foi significativa para os inseticidas Certero, Dimilin, Tracer, Engeo Pleno, Lorsban 480 BR, Sevin 480 SC.
RESUMO
ABSTRACT The goal of this work was to evaluate the selectivity of insecticides used in corn crops for the control of Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) on first-instar nymphs and eggs of the earwig Doru lineare. For the bioassays the standardized methodology of IOBC/WPRS was used in terms of temperature (25 ± 1º C), relative humidity (70 ± 15%) and photophase (14 hours). In the bioassay with nymphs for residual contact, the applications of insecticides was conducted with equipment pressurized by CO2 to 50 psi. For applications of insecticides on eggs, a Potters tower was used, with pressure of 10 psi. In both forms of spraying the deposit was 1.75±0.25 mg cm-2 of aqueous solution in accordance with the IOBC/WPRS methodology. The mortality of nymphs was used to classify insecticides as harmless ( 30%), slightly harmful (30-79%), moderately harmful (80-99%) and harmful (> 99%). Viability of eggs and survival of hatched nymphs were both evaluated by comparing with the positive (Sevin 480 SC) and negative (water) controls. The viability of eggs was reduced by Certero, Dimilin, Engeo Pleno, Karate Zeon 250 SC, Lorsban 480 BR, Match EC and Sevin 480 SC. The survival of nymphs from treated eggs was reduced by the insecticides Decis EC, Dimilin, Engeo Pleno, Karate Zeon 250 CS, Lorsban 480 BR and Sevin 480 SC. For nymphs of D. lineare in residual contact, all the insecticides were harmful.
RESUMO O objetivo do trabalho foi avaliar a seletividade de inseticidas usados na cultura do milho para o controle de Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) sobre ninfas de primeiro ínstar e ovos do predador Doru lineare (Scudder, 1876) (Dermaptera: Forficulidae). Para os bioensaios foi utilizada a metodologia padronizada da IOBC/WPRS, em condições de laboratório, com temperatura de 25 ± 1º C, umidade relativa de 70 ± 10% e fotofase de 14 horas. No bioensaio com ninfas para contato residual, a aplicação dos inseticidas foi realizada com um equipamento pressurizado a CO2, pressão de 50 psi. Para aplicação dos inseticidas sobre os ovos foi utilizada torre de Potter, com pressão de 10 psi. Em ambas as formas de aplicação o depósito foi de 1,75 ± 0,25 mg de calda cm-2 conforme metodologia da IOBC/WPRS. A mortalidade de ninfas foi utilizada para classificar os inseticidas como inócuo ( 30%), levemente nocivo (30-79%), moderadamente nocivo (80-99%) e nocivo (> 99%). Os dados de viabilidade de ovos e sobrevivência de ninfas que eclodiram deles foram comparados com os dados das testemunhas positiva (Sevin 480 SC) e negativa (água). Certero, Dimilin, Engeo Pleno, Karate Zeon 250 SC, Lorsban 480 BR, Match EC e Sevin 480 SC reduziram a viabilidade de ovos. A sobrevivência de ninfas provenientes dos ovos tratados teve redução para os inseticidas: Decis 25 EC, Dimilin, Engeo Pleno, Karate Zeon 250 CS, Lorsban 480 BR e Sevin 480 SC. Para ninfas de D. lineare em contato residual, todos os inseticidas foram nocivos em 96 horas após a exposição.