Divergência genética de cultivares de arroz quanto à resistência a Tibraca limbativentris Stål (Hemiptera: Pentatomidae)

Abstract

-The genetic divergence of sixteen rice cultivars regarding their resistance to the rice stem bug, Tibraca limbativentris Stål, was estimated by multivariate analysis techniques. The experiment was carried out in greenhouse, in randomized block design with eight replications. Eight plant resistance related traits were evaluated. Genetic divergence was evaluated by multivariate procedures: generalized Mahalanobis (D 2 ) distance, the Tocher's grouping optimization method and canonical variables. The most dissimilar cultivars were Bico Ganga and Marabá Branco, while Agulha and Branco Tardão were the most similar. Five clusters were formed by the Tocher's optimization method. Three canonic variables explained 88.5% of the observed variation. We concluded that the multivariate analysis techniques are suitable for analyzing the genetic divergence among rice cultivars, indicating Bico Ganga and Marabá Branco as the most promising for future breeding programs of resistance to the rice stem bug.KEY WORDS: Plant breeding, rice stem bug, multivariate analysis RESUMO -A divergência genética de 16 cultivares de arroz quanto à resistência ao percevejo-docolmo-do-arroz, Tibraca limbativentris Stål, foi avaliada por meio de técnicas de análise multivariada. O experimento foi conduzido em casa de vegetação, em delineamento experimental de blocos ao acaso, com oito repetições. Na avaliação foram considerados oito caracteres de resistência ao ataque do inseto. A divergência genética foi avaliada por procedimentos multivariados: distância generalizada de Mahalanobis (D 2 ), método de agrupamento de otimização de Tocher e técnica de variáveis canônicas. As cultivares mais dissimilares foram Bico Ganga e Marabá Branco, enquanto Agulha e Branco Tardão foram as mais similares. Foram formados cinco grupos pelo método de otimização de Tocher. As três primeiras variáveis canônicas explicaram 88,5% da variabilidade total disponível. Conclui-se que as técnicas de análise multivariada são efi cientes para a análise da divergência genética entre as cultivares de arroz, com destaque para Marabá Branco e Bico Ganga, consideradas as mais promissoras a serem utilizadas em futuros cruzamentos para melhoramento visando resistência ao percevejo-do-colmo-do-arroz. PALAVRAS-CHAVE: Melhoramento de plantas, percevejo-do-colmo-do-arroz, análise multivariada O Brasil é o nono produtor mundial de arroz, Oryza sativa, e, excluindo-se os países asiáticos, o maior produtor. A metade da população mundial tem o arroz como sua principal fonte de alimento. As médias de produção e consumo de arroz no Brasil nos últimos dez anos foram de, respectivamente, 10,3 e 11,6 milhões de toneladas (Ferreira et al 2005). A

Spatialization of Tibraca limbativentris Stål in irrigated rice: a geostatistical approach

“…This species occurs throughout the phenology of rice, varying its damage according to the stage of the crop. When it attacks the culm, the symptom called dead heart occurs, reducing the plant stand (SOUZA et al, 2009). In the reproductive stage, generates the panicle formation of white or partial sterility of spikelets, which is the most influential component in reducing the yield of rice grains (OLIVEIRA et al, 2010).…”

Resistance in Rice to Tibraca limbativentris (Hemiptera: Pentatomidae) Influenced by Plant Silicon Content

“…Palabras Clave: chinche de arroz; planta resistencia a insectos; resistencia inducida; Oryza sativa Among the principal factors that contribute to the reduction of productivity in rice cultivation in Brazil are the rice stink bugs that attack the stem and the panicle of the plant (Souza et al 2009;Quintela et al 2013). The predominant species in Brazil and other South American countries include the rice stalk stink bug, Tibraca limbativentris (Stål) (Hemiptera: Pentatomidae), and the panicle feeding stink bugs, Oebalus poecilus (Dallas) and Oebalus ypsilongriseus (De Geer) (Hemiptera: Pentatomidae) (Pantoja et al 2007).…”

“…The adult of T. limbativentris is brown with pale yellowish lateral margins of the body, and a long head with piercing-sucking mouth-parts (Fernandes & Grazia 1998). Oviposition occurs on the surface of the leaves, the eggs becoming greenish and darker with development (Souza et al 2009). The insect prefers the lower part of the rice stem for feeding and reproduction (Souza et al 2009).…”

“…Oviposition occurs on the surface of the leaves, the eggs becoming greenish and darker with development (Souza et al 2009). The insect prefers the lower part of the rice stem for feeding and reproduction (Souza et al 2009). Damage is first observed beginning with the second instar by feeding at the base of the plant, which causes dead tillers (dead hearts) in the vegetative stage and unfilled panicles (whiteheads) in the reproductive stage (Costa & Link 1992;Pazini et al 2012).…”

Toxicity of essential oils from leaves of Piperaceae species in rice stalk stink bug eggs, Tibraca limbativentris (Hemiptera: Pentatomidae)

“…The occurrence of this pest has increased due to greater crop acreage, and favorable climatic and agronomic practices Grützmacher;Cunha, 2004;Rampelotti et al, 2007). Currently, the control of T. limbativentris is accomplished with synthetic chemical insecticides (Rampelotti-Ferreira et al, 2010;Souza et al, 2009). …”