Inseticidas químicos e extratos vegetais aquosos no controle de Sitophilus zeamais em grãos de milho sob condições de armazenamento
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Data
2012-12-13
Autores
Vilarinho, Marcella Karoline Cardoso
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Universidade Federal de Mato Grosso
Resumo
The Sitophilus spp. is a major pest of stored grain, which is controlled by the use of
chemical insecticides, but their indiscriminate use has been causing a lot of undesirable
factors to humans and to the environment. And so as a less harmful alternative, natural
insecticides come as an option for combating the insects, which simultaneously decrease the
risk of damage to the environment. The study was carried at the Institute of Agricultural
Sciences and Technology, campus of Rondonópolis at the Federal University of Mato Grosso,
in the period of March to September, 2012. The experiment was performed under three
different conditions. The experiment consisted of three environments: AI-temperature and
humidity, humidity control, AII, and AIII-control humidity and temperature. AIII maintained
at ambient temperature was 25.1 ° C and humidity 70 % (average), the latter being also held
in the environment variable AII. The aqueous extracts were obtained by addition of post-plant
garlic, lemongrass and neem in distilled water at a ratio of 5 g per 100 ml, and dosages of
chemical insecticides were 0.04 and 0.15 ml/100 ml water for Deltamethrin and Chlorpyrifos
respectively. Treatments were added to the corn grains placed in glass containers of 2.5 L
(plots) and mixed by manual agitation until a uniform, being removed the excess product to
avoid higher concentration at certain points. Each experimental unit was infested with 20
adults of Sitophilus spp. not sexed. The experiment was maintained without reinfestation of
insects. The grains were stored for a period of 90 days in the three storage environments. The
variables analyzed were: counting insects, water content in the grains, electrical conductivity
and germination test. At the end of the experiment was also evaluated the qualitative loss of
grain weight and specific gravity. The variables were analyzed every 30 days of the
experiment, with three periods (30, 60 and 90 days). The analyzes were obtained using Tukey
at 5 % probability. On day 30 we observed high efficiency of chemical insecticides
Chlorpyrifos and Deltamethrin in control of Sitophilus spp. in the three storage environments.
But it was noticeable that the natural insecticide were not effective in controlling insects,
which can be confirmed in the qualitative evaluation at the end of the experiment. The high
number of insects caused further damage to beans and alter the values of electrical
conductivity and water content in the grains. The observed relationship between lower bulk
density, with the highest percentages of water content in the grains and number of insects
Germination was reduced in all treatments in all three environments, and may infer that the
adverse storage conditions may have influenced this fall.
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VILARINHO, Marcella Karoline Cardoso. Inseticidas químicos e extratos vegetais aquosos no controle de Sitophilus zeamais em grãos de milho sob condições de armazenamento. 2012. 84 f. Dissertação (Mestrado em Engenharia Agrícola) - Universidade Federal de Mato Grosso, Instituto de Ciências Agrárias e Tecnológicas, Rondonópolis, 2012.