RESUMO: Bicudo-do-algodoeiro é a principal praga do algodoeiro no Brasil, sendo o uso de inseticidas amplamente recomendado para o seu controle. A suscetibilidade do bicudo-do-algodoeiro foi determinada a inseticidas em formulação simples ou em misturas prontas para uso, as quais têm sido recomendadas para pulverizar campos de algodão sob a hipótese de serem mais tóxicas à praga alvo. Assim, curvas de concentração-mortalidade foram determinadas para adultos do bicudo contaminados, simultaneamente, via resíduo seco e ingestão dos inseticidas. Dez formulações foram estudadas, sendo cinco misturas (lambda-cialotrina + tiametoxam, lambda-cialotrina + clorantraniliprole, tiametoxam + clorantraniliprole e fenitrotiona + esfenvalerato) e suas respectivas cinco formulações simples. Folhas e cotilédones do algodoeiro foram mergulhados em diluições do inseticida preparadas com os produtos comerciais e água destilada. A mortalidade adulta foi avaliada 48 horas após o acondicionamento dos adultos em materiais tratados e não tratados. As concentrações de CL50s variaram de 0,004 a 0,114 g i.a./L, com potência relativa entre formulação simples e misturas, variando de 1,37 a 29,59 vezes. A lambda-cialotrina e o tiametoxam em formulações simples foram os inseticidas mais tóxicos para o bicudo. Entre as misturas, aquela preparada com lambda - cialotrina + clorantraniliprole resultou em um efeito sinérgico, enquanto as demais misturas mostraram um efeito antagonista. Portanto, exceto pela mistura de lambda-cialotrina + clorantraniliprole, as demais misturas não demonstraram maior toxicidade para o bicudo-do-algodoeiro e devem ser recomendadas somente quando objetivam finalidades diferentes.

ABSTRACT: Boll weevil is the major cotton pest in Brazil, and insecticides are widely recommended against it. We determined the susceptibility of boll weevil to insecticides either in single or in mixture ready-to-use formulations, which are registered to spray cotton fields under the hypothesis that mixtures are more toxic to the target pest. Concentration-mortality curves were determined to adult species, simultaneously through dried residues and ingestion. Ten insecticide formulations were studied with five in mixture (lambda-cyhalothrin + thiamethoxam, lambda-cyhalothrin + chlorantraniliprole, thiamethoxam + chlorantraniliprole, and fenitrothion + esfenvalerate) and their five respective single formulations. Cotton leaf discs and cotyledons were dipped into insecticide dilutions prepared by diluting the commercial products into distilled water. Adult mortality was assessed 48 hours after caging adults on treated and untreated materials. The LC50s-concentrations varied from 0.004 to 0.114 g a.i./L, with a relative potency between single and mixture ones, varying from 1.37- to 29.59-fold. Furthermore, lambda-cyhalothrin and thiamethoxam in single formulation were the most toxic insecticides to boll weevil. Among insecticide mixtures, only lambda-cyhalothrin + chlorantraniliprole resulted in a synergic effect; whereas the remaining mixtures showed an antagonistic effect. Therefore, except for the mixture of lambda-cyhalothrin + chlorantraniliprole, the remaining mixtures did not enhance toxicity against the boll weevil and should be recommended only when aimed at different purposes.

ABSTRACT: The boll weevil colonizes cotton fields as early as cotton squaring, causing significant losses due to feeding and protected development inside fruiting structures throughout crop phenology. Successful control depends on control of adults and their accurate detection when they colonize the crops. The commercial trap and boll weevil attract-and-control tubes (BWACT) are the only available tools to monitor and attract-and-kill boll weevil, despite limitation in efficacy, and insecticide in BWACT is not allowed in organic production. A grandlure-and-glue reusable and insecticide-free tube (GGT) made with polyvinyl chloride tube, smeared with entomological glue, and lured with pheromone was tested to detect boll weevil activity across various seasons. Boll weevil showed activity during growing season and off-season from 2009 to 2012 in the Semiarid and with higher numbers captured in GGT in comparisons to commercial traps. GGT was able to detect early weevils in the field right after planting. Further, the overall averages resulted in 34-, 16.8-, and 7.5-times more weevils captured in GGTs compared to the traps during stalk destruction in the Semiarid 2011 and Cerrado season 2012/13 and during the harvesting period in the Cerrado season 2011/12, respectively. Therefore, boll weevils were captured actively during season and off-season and early captures obtained in GGT compared to traps showed a better correlation between captures and square damage.

O pulgão Aphis gossypii Glover (Hemiptera: Aphididae) é uma importante praga do algodoeiro, independente do sistema de cultivo convencional ou orgânico. Entretanto, no cultivo orgânico não é permitido a utilização de inseticidas sintéticos, o que dificulta o controle desta praga. Assim, avaliou-se o controle e a proteção da planta à infestação pelo pulgão com inseticidas permitidos em cultivo orgânico. O experimento de controle empregou três inseticidas naturais [Beauveria bassiana (Boveril®), óleo de nim (Neemseto®) e óleo de algodão comparado ao inseticida sintético tiametoxam (Actara®)]. O experimento visando a proteção da planta à infestação foi conduzido com os mesmos inseticidas exceto o Boveril® . As avaliações foram realizadas após 72 e 120h para os experimentos de controle e de proteção da planta, respectivamente. O controle do pulgão 72h após a aplicação foi similar entre óleo de algodão, Neemseto® e Actara® e atingiu 100% de controle com o Actara®. Em relação à proteção da planta contra a colonização, o Actara® destacou-se com maior proteção das plantas quando comparado aos demais inseticidas, sendo a eficiência mantida em todos os intervalos de avaliação. Já os demais tratamentos apresentaram variabilidade com relação à proteção ao longo dos intervalos de avaliação.

The cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae), is a key pest of cotton, irrespective of the use of conventional or organic management. In organic systems, however, the use of synthetic insecticides is not allowed, increasing the difficulty of controlling this pest. This work evaluated aphid control and the ability of products to prevent aphid infestation using natural insecticides compared to a standard synthetic insecticide. The control trial was conducted with four products [Beauveria bassiana (Boveril®), neem oil (Neemseto®), and cotton seed oil compared to thiamethoxam (Actara®)], and untreated plants served as the control group. The trial testing the efficacy of these products in preventing aphid infestation was conducted using the same products, excluding Boveril®. The evaluations were conducted 72 and 120h post-treatment for the efficacy and the protection against colonization trials, respectively. The aphid control by cotton seed oil, Neemseto®, and thiamethoxam was similar, with 100% control being achieved on the thiamethoxam-treated plants. Regarding the plant protection against aphid colonization, the insecticide thiamethoxam exhibited a better performance compared to the other tested products with steady results over the evaluation period. The natural products exhibited variable results with low protection against plant colonization throughout the evaluation period.