Influência da temperatura do ar e da umidade do solo na eficácia de aplicações foliares de inseticidas para o controle de Bemisia tabaci Biótipo B(Hemiptera: Aleyrodidae) em soja
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2020-06-25
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Universidade Federal de Goiás
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The ubitiquous Bemisia tacaci biótipo B, causes economical losses to many crops. The development of this pest is favored in hot climates and in seasons of low rainfall and high temperatures. These abiotic factors cause plant stress, change their metabolism and can effect the insecticides efficacy for its control. This study aims to verify the air temperature (10, 15, 17, 20, 23, 25, 28, 31, 35 and 36 °C) and soil moisture (13, 19, 25, 38 e 50% of field capacity) effects on the efficacy of sintetic insecticides for the control of nymphs and adults of whitefly in soybeans. Active ingredients in simple formulation or in mixture (with new mode of action) were tested: cyantraniliprole (100 g a.i./L), pyriproxyfen + acetamiprid (100+200 g a.i./L), pyriproxyfen (100 g a.i./L), abamectin (18 g.a.i./L) e cyantraniliprole + abamectin (60+18 g a.i./L). Mortalities of adults by the insecticides were higher at 35-36°C in comparison to 15, 20, 23, 25 and 28-30°C. The LT50 was lower for the insecticides at 35-36°C compared to the other temperatures, varying from 12.8 (35±0.3 ºC) to 53.6 (10±0.8 ºC) hours. In general, some insecticides killed more adults and nymphs at the lowest soil moisture (25%) and it was not observed soil moisture effect for the other Insecticides. At 13 and 19% soil moistures, the plants dried up and it was not possible to evaluate the effect of soil moisture on insecticides efficacy. The LT50´s ranged from 1.9 to 3.3 (25%) and 2.1 to 2.7 (50%) and for nymphs ranged from 3.3 to 6.9 (25%) and 2.1 to 2.7 (50%) days. Therefore, high temperatures and water stress enhanced insecticide efficacy to whitefly. It can be concluded that high temperatures and periods of water plant restrictions do not affect insecticides efficacy against whitefly. But temperatures under ≤ 20 °C may diminish the insecticides efficacy and increase the median lethal time to kill whitefly adults.
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SANTILLI, C. Influência da temperatura do ar e da umidade do solo na eficácia de aplicações foliares de inseticidas para o controle de Bemisia tabaci Biótipo B(Hemiptera: Aleyrodidae) em soja. 2020. 72 f. Dissertação (Mestrado em Agronomia) - Universidade Federal de Goiás, Goiânia, 2020.