Seleção de clones de braquiária para resistência à lagarta-do-cartucho

Abstract

Resumo -O objetivo deste trabalho foi avaliar e selecionar clones de braquiária (Urochloa ruziziensis) resistentes à lagarta-do-cartucho, Spodoptera frugiperda (Lepidoptera: Noctuidae), para uso em sistema de integração lavoura-pecuária-floresta. Foram avaliados 147 clones de U. ruziziensis em delineamento inteiramente casualizado, com três repetições. Como testemunha e padrão de suscetibilidade, foi utilizada uma dieta artificial adequada ao desenvolvimento do inseto. Folhas dos diferentes clones de U. ruziziensis foram coletadas e oferecidas como alimento aos insetos, mantidos individualizados em unidades de criação. Foram avaliadas a sobrevivência, a duração e a biomassa de lagartas e pupas. Observaram-se diferenças significativas entre os clones para todas as características avaliadas, o que evidencia a influência acentuada dos clones de U. ruziziensis no desenvolvimento de S. frugiperda. Foram identificados 20 clones nos quais não houve desenvolvimento da lagarta e 55 clones nos quais houve sobrevivência média das lagartas de 33%. Para os demais clones, que se mostraram melhores hospedeiros, o desenvolvimento do inseto foi afetado pela maior duração do estágio larval e pela redução da biomassa da pupa. Os resultados obtidos são indicativos do potencial de utilização de clones de Urochloa ruziziensis para redução de populações de Spodoptera frugiperda em sistema de integração lavoura-pecuária-floresta.Termos para indexação: Spodoptera frugiperda, Urochloa ruziziensis, integração lavoura-pecuária-floresta, resistência de plantas. Selection of signal grass clones for resistance to fall armywormAbstract -The objective of this work was to evaluate and select signal grass (Urochloa ruziziensis) clones resistant to fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), for use in a crop-livestock-forest integration system. One hundred and forty-seven clones of U. ruziziensis were evaluated in a completely randomized design with three replicates. An artificial diet, adequate for insect development, was used as a control and susceptibility standard. Leaves of different U. ruziziensis clones were collected and offered as food to the insects, kept individually in rearing units. Larval survival, duration, and biomass of larvae and pupa were evaluated. Significant differences were observed between clones for all evaluated traits, showing the marked effect of U. ruziziensis clones on the development of S. frugiperda. Twenty clones were identified in which there was no development of larvae and 55 clones in which there was an average larval survival of 33%. For the other clones, which were better hosts, insect development was affected by the longer larval stage and by the reduction in pupa biomass. The obtained results show the potential of using Urochloa ruziziensis clones for the reduction of Spodoptera frugiperda populations in a crop-livestock-forest integration system.

Crop-Livestock Integration: Attack of Spodoptera frugiperda (Lepidoptera: Noctuidae) on transgenic maize and Bachiaria brizantha (Poaceae)

“…Different species of the genus Brachiaria spp. were good hosts for S. frugiperda, allowing the complete development of this insect (Auad et al, 2016). Thus, selecting plants that minimize the biotic potential of this insect pest is one of the challenges in intercropped plantations in the CLI.…”

Modeling fall armyworm resistance in Bt-maize areas during crop and off-seasons

“…In Brazil, forage crops are cultivated for other purposes. Species such as Bermuda grass (Cynodon dactylon) are commonly used as a "green bridge" in the off-season (Ribeiro et al 2020), or in integrated crop-livestock systems where green forage is used for animal feed (Auad et al 2016). As far as we are aware, published studies have addressed only the contribution of alternative host species to the maintenance of pest populations in the eld during the crop season (Ribeiro et al 2020).…”

Adaptability and Comparative Biology of Fall Armyworm on Maize and Perennial Forage Species and Relation with Chemical-Bromatological Composition

“…Many studies have reported on forage lines resistance attributes (levels, types, and mechanisms of resistance) to lepidopterous pest species (Lynch et al 1981, Wiseman & Duncan 1996, Braman & Duncan 2000, Auad et al 2016. However, to date, there are no reports comparing fall armyworm development and adaptability on forage species and row crops largely cultivated in Brazil (i.e., corn and soybean).…”

“…Caterpillars (Lepidoptera) are potential pests of pastures capable of consuming rapidly large productive areas worldwide (Auad et al 2016). Despite their seasonal occurrence, caterpillars exhibit great voracity, especially for their ability to scrape and consume leaves, reducing forage availability and pasture support capacity (Ribeiro & Castilhos 2018).…”