Produção Nacional
Revisado por pares
Challenges in chemical management of soybean looper (Chrysodeixis includes) using several insecticides
2019; Southern Cross Publishing; Issue: 13(10):2019 Linguagem: Inglês
10.21475/ajcs.19.13.10.p2052
ISSN1835-2693
AutoresClérison Régis Perini, Jonas André Arnemann, Lucas de Arruda Cavallin, Gabriel A. Guedes, Rafael Paz Marques, Ivair Valmorbida, Karina da Silva, Natalie M. Feltrin, Letícia Puntel, Ricardo Froehlich, Jerson Vanderlei Carús Guedes,
Tópico(s)Insect and Pesticide Research
ResumoSoybean looper, Chrysodeixis includens (Walker, [1858]) (Lepidoptera: Noctuidae), is the most important caterpillar pest in Brazil due to its high tolerance to insecticides and control failures that have been reported in fields. Based on this, we assessed the performance of several insecticides against C. includens on soybean over three seasons (2014, 2015, and 2016), performing four experiments in southern Brazil. Experiments I / 2014, II / 2015, III / 2016 were carried in completely randomized block designs with eight insecticides. Experiment IV / 2016 was arranged in completely randomized block design in an 8 x 2 factorial arrangement, eight insecticides x two spraying time. Mortality of small (< 1.5 cm) and large (> 1.5 cm) soybean looper larvae was assessed with a vertical beat cloth, sampling in each plot 1.0 m2 at 3, 7 and 10 days after spray. Percentage of defoliation injury was assessed visually comparing to a scale of soybean leaf injury in experiment IV / 2016. Data were subjected to one-way (type I SS) analysis of variance (ANOVA) using the general linear models. The insecticides indoxacarb and chlorfenapyr had consistently high mortality upon small and large larvae of C. includens. Spinosyn, spinosad and spinetoram insecticides showed higher effect over small larvae (< 1.5 cm) than large (> 1.5 cm). Number of spraying was significant for spinetoram and indoxacarb that increased mortality of large larvae (from 4.50 to 2.75 and from 3.75 to 0.87 larvae m-2, respectively) and reduced defoliation injury significantly (from 22.5% to 9.3% and from 14.5% to 3.3%, respectively) with two applications. The treatment chlorfluazuron+acephate showed low defoliation injury in 2016 but did not affect larval density. Chlorfenapyr showed reduced defoliation (3.0%) and low larvae density (1.37 larvae m-2) with only one application. Spinosyns have satisfactory control of small larvae and indoxacarb and chlorfenapyr show high mortality of both sizes, small and large larvae. Therefore, we recommend that 7 days from the first one, a second application should be considered for indoxacarb, and spinetoram to achieve higher mortality. Considering our results, we demonstrate that the satisfactory control of soybean looper larvae is difficult to achieve with most chemical insecticides. It needs a more accurate management strategy of C. includens in soybeans.
Referência(s)