RESUMEN

The Tibraca limbativentris is a pest that causes rice crop damage and may lead to grain yield reductions of up to 90%. The most commonly used tactic for T. limbativentris control is chemical, which causes adverse effects on the environment. This study was conducted to identify sources of antixenosis and antibiosis resistance to T. limbativentris mediated by the hardness and diameter of the stem of the rice plant. Antibiosis and antixenosis tests were carried out with 22 rice genotypes of Brazilian and Asian origin. The Canela de Ferro, BRS Esmeralda, and Desconhecido Branco genotypes had the lowest proportions of stems showing symptoms of the damage caused by T. limbativentris. Canela de Ferro, Primavera, and IR 22 genotypes had the lowest nymphs survivorship and the genotypes Marabá Branco, Marabá, Skirivimankoti, Pepita, BR IRGA 409, Curinga, IR 40, Bonança, Desconhecido Branco, Bico Ganga, Primavera, and BRS Esmeralda were the least attractive to the insects. The genotypes BRS Esmeralda, Primavera, Desconhecido Branco, and Canela de Ferro were resistant to the rice stalk stink bug by antibiosis and/or antixenosis. These genotypes can be used directly by rice farmers for T. limbativentris management. Molecular biology studies should be conducted to identify and characterize resistance genes in these genotypes so that they can be used in breeding programs.

Asunto(s)

RESUMEN

This study evaluates the effects of combinations of pyrethroids and neonicotinoids on the control of stink bugs at different stages of soybean crop development. The experiment was set up in a factorial randomized block design (4×6: 4 treatments and 6 stages) with 4 repetitions. The following treatments were tested during the V6/V7, R2, R4, R5.1, R5.5 and R 6 phenological stages: 1 ­ control (no application), 2 ­ thiamethoxam + λ-cyhalothrin, 3 ­ acetamiprid + α-cypermethrin, and 4 ­ dinotefuran + α-cypermethrin. Infestation, number of damaged seeds, number of pods, number of pods per plant, and yield (kg/ha) were evaluated. Stink bug infestations were smaller when applications commenced during the vegetative stages (V6-V8). Pod numbers and yields were highest in the dinotefuran + α-cypermethrin treatment with applications from V6/V8 to R4. The active ingredients dinotefuran + α-cypermethrin reduced stink bug populations and increased yields and could therefore be considered in integrated pest management (IPM) programs for soybean crops.(AU)

O objetivo deste trabalho foi avaliar o efeito de combinações de piretroides com neonicotinoides no controle de percevejos em diferentes estádios de desenvolvimento da cultura da soja. O delineamento experimental foi em blocos randomizados, em esquema fatorial 4×6 (4 tratamentos e 6 estádios) com 4 repetições. Os produtos utilizados foram: 1 ­ testemunha (sem aplicação), 2 ­ tiametoxam + λ-cialotrina, 3 ­ acetamiprida + α-cipermetrina, e 4 ­ dinotefuran + α-cipermetrina, e as aplicações foram realizadas a partir dos estádios fenológicos V6/V7,R2, R4, R5.1, R5.5 e R6. Avaliaram-se a infestação, número de grãos danificados, número de vagens, número de vagens por planta e produtividade (kg/ha). A infestação de percevejo foi menor quando se iniciou a aplicação precocemente nos estádios vegetativos (V6-V8).O número de vagens e produtividade foi superior no tratamento dinotefuran + α-cipermetrina nos estádios V6/V8 até R4. Os ingredientes ativos dinotefuran + α-cipermetrina apresentaram resultados positivos na redução da população de percevejo e proporcionaram incremento no rendimento de grão, podendo ser utilizado como opção em programa de manejo integrado de pragas (MIP) na cultura da soja.(AU)

Asunto(s)

RESUMEN

Abstract The occurrence of the black caterpillar Spodoptera cosmioides (Lepidoptera: Noctuidae) has been increasing in soybean crops in Brazil leading to yield losses. The objective of this study was to evaluate antibiosis in soybean genotypes to S. cosmioides. The following parameters were evaluated: duration, viability and larval weight; duration and viability of the pre-pupal; duration, weight and viability of pupa; total cycle and sex ratio. The design was completely randomized with 18 treatments (genotypes) and 30 replicates. The genotypes PI 227687, PI227682, IAC 100 and BRS 7270 IPRO showed significant levels of antibiosis against S. cosmioides. These results will be useful for soybean producer or in breeding programs focusing on host plant resistance.