Insecticides action of neonicotinoids group in fall armyworm (Spodoptera frugiperda) control on bean leaves (Phaseolus vulgaris)

Among several factors that impact the bean culture productivity there are pest insects, which affect the plant since seeding until postharvest, causing loss in the culture yield. The fall armyworm (Spodoptera frugiperda) stands out among the main pests of common bean (Phaseolus vulgaris). The aim of this work was to evaluate the effectiveness of insecticides of the neonicotinoid group in the control of the fall armyworm in the bean crop, comparing dinotefuran, acetamiprid, thiamethoxam and imidacloprid performance. Experimental design was composed of blocks entirely randomized, with 9 treatments and 10 replicates. Three caterpillars, at the stage of second instar, were used in each experiment, focusing on the ingestion of leaves containing the treatments. Evaluations were realized in the intervals of 1, 3, 6 and 8 days after every application, counting the number of caterpillars alive in the Petri's dish, attributing visual notes on bean leaves, according to the foliar area affected (consumed). The dinotefuran treatment with the highest dose presented superior efficiency at 80% in the first evaluation. The thiamethoxam treatment with the lowest dose, in the latest analyses, showed efficient superior at 90%. The major doses of all treatments presented efficiency higher than 80% in the last evaluations, being efficient in the S. frugiperda control.

Ação residual de inseticidas para larvas e adultos do predador Cycloneda sanguinea Linnaeus, 1763 (Coleoptera: Coccinellidae) / Residual action of insecticides to larvae and adults of the predator Cycloneda sanguinea Linnaeus, 1763 (Coleoptera: Coccinellidae)

A ação residual dos inseticidas imidacloprido/Beta-ciflutrina, clotianidina e clorfenapir foi avaliada para larvas de terceiro ínstar e adultos do predador Cycloneda sanguinea (Linnaeus). Sementes de algodão da cultivar BRS IPÊ foram semeadas em vasos de PVC e as plantas foram mantidas em casa de vegetação. Ao atingirem 25 dias de idade, as plantas foram pulverizadas com os produtos nas menores dosagens recomendadas pelos fabricantes, utilizando-se pulverizador manual. As concentrações foram em g i.a.L-1 de água: imidacloprido/Beta-ciflutrina (100/12,5 SC -0,25/0,03), clotianidina (500 PM ­ 0,33) e clorfenapir (240 SC ­ 0,80). Água destilada foi utilizada como testemunha. Folhas previamente marcadas em cada planta, de cada tratamento, foram retiradas e levadas ao laboratório e colocadas em placas de Petri contendo solução de ágar bacteriológico. Ovos de Anagasta kuehniella (Zeller) foram colocados sobre as folhas de algodoeiro e, em seguida, liberou-se um espécime por placa. As liberações ocorreram após 1, 12, 23 e 35 dias da pulverização dos compostos. Cada placa de Petri foi imediatamente vedada com filme de plástico PVC. O delineamento foi inteiramente casualizado com quatro tratamentos e doze repetições sendo que, para os testes com larvas, cada parcela foi formada por três espécimes e, para aqueles com adultos, cada repetição correspondeu a um casal. As avaliações de mortalidade foram feitas após 12, 24 e 48 horas das liberações. Os produtos foram classificados de acordo com o proposto pela Organização Internacional para Controle Biológico (IOBC). Todos os produtos foram enquadrados na classe 4 = persistentes, visto que mesmo a partir do trigésimo dia após sua aplicação causaram mais de 30,0% de mortalidade dos predadores.

The residual action of the insecticides imidacloprid/Beta-cyfluthrin, clothianidin and chlorfenapyr was evaluated in regard to third-instar larvae and adults of the predator Cycloneda sanguinea (Linnaeus). Cotton seeds of the cultivar BRS IPÊ were sowed in PVC pots and the plants were maintained in the greenhouse. Upon reaching 25 days of age, the plants were sprayed with the lowest dosages of the products recommended by the manufacturers, using a manual sprayer. The insecticides evaluated in g a.i.L-1 of water were imidacloprid/Beta-cyfluthrin (Imidacloprido/Beta-ciflutrina 100/12.5 CS ­ 0.25/0.03), clothianidin (Clotianidina 500 WP ­ 0.33) and chlorfenapyr (Clorfenapir 240 CS0.80). Distilled water was used as a control. Previously marked leaves, from each treatment, were removed from the plants and taken to the laboratory where they were placed in Petri dishes containing bacteriologic agar solution. Eggs of Anagasta kuehniella (Zeller) were placed on cotton leaves following the release of a Trichogramma specimen per dish after 1, 12, 23 and 35 days from pesticides application. Each Petri dish was immediately closed with plastic PVC film. A completely randomized experimental design was used, with 4 treatments and 12 replicates, each one formed by 3 third-instar larvae or 1 couple of adults. The number of dead larvae and adults in each treatment was examined 12, 24 and 48 hours after exposure to the chemicals. The products were classified according to categories proposed by the International Organization for Biological Control (IOBC). All the compounds tested were evaluated as class 4 = persistent, causing mortality above 30% up to 31 days after application on cotton leaves.

Avaliação do efeito de inseticidas sobre a joaninha Hippodamia convergens Guérin-Meneville (Coleoptera: Coccinellidae) em algodoeiro / Evaluation of the effect of insecticides on lady beetles Hippodamia convergens Guérin-Meneville (Coleoptera: Coccinellidae) in cotton plant

A associação dos métodos químico e biológico no controle de pragas é fundamental na sustentabilidade do sistema agrícola, auxiliando a redução de químicos derivados de petróleo. O objetivo do trabalho foi avaliar o efeito de inseticidas sobre o coccinelídeo predador Hippodamia convergens, na cultura do algodoeiro, em condições de laboratório e de campo. Foram estabelecidos os seguintes tratamentos, expressos em g ou mL de p.c. do inseticida por hectare: flonicamida a 50, 80 e 150 g, tiametoxam a 200 g, acetamiprido a 150 g, imidacloprido a 250 mL e testemunha sem aplicação. A avaliação do efeito dos inseticidas aplicados diretamente e indiretamente (efeito de contato em resíduo seco do inseticida) sobre H. convergens, foi realizada por meio da quantificação de insetos sobreviventes após a aplicação. Com base nos resultados dos experimentos, pode-se concluir que dentre os inseticidas avaliados, flonicamida ocasionou a menor mortalidade de H. convergens. Os inseticidas tiametoxam, acetamiprido e imidacloprido apresentaram comportamento semelhante, acarretando alta mortalidade de H. convergens.

The combination of chemical and biological methods to control pests is essential to ensure the sustainability of agricultural system, to reduce using of chemicals products. The objective this work was to evaluate the effects of insecticides on the coccinellid predatory Hyppodamia convergens, the cotton plant, in conditions laboratory and field. Were the following treatments established, expressed in g or mL of active ingredient of insecticide per hectare: flonicamid to 50, 80 and 150 g, thiamethoxam at 200 g to 150 g acetamiprid, imidacloprid to 250 mL and control without application. The evaluation effect of insecticides applied directly and indirectly (residual effects on leaves) on H. convergens, was performed by quantification of insects survived to 7 days after application. Based on the results of experiments, we can conclude that among the insecticides evaluated, flonicamid caused the lower mortality of H. convergens. The insecticides thiamethoxam, acetamiprid and imidacloprid showed similar behavior, causing high mortality of H. convergens.