The Impact of Pesticides - Academy Publish

Integrated Pest Management as a Tool to Mitigate thePesticide Negative Impact Into the Agroecosystem: TheSoybean ExampleAdeney de Freitas Bueno & Regiane Cristina Oliveira de Freitas BuenoABSTRACTThe increasing global food demands have lead to a constant battle for higher cropyields. Combined with the relative low costs of some insecticides such event hastriggered an excessive use of pesticides in the agriculture. Among the side effects ofpesticide abuse, especially the non-selective ones are: the reduction of efficacy ofthe natural biological controls; fast pest resurgence; and resistance selection to theinsecticides used, besides the danger to the environment and human health. Toaddress these problems and still maximize agricultural production, pest controlprograms must be guided by a proper Integrated Pest Management (IPM) approach.The IPM is based on the premise that plants can tolerate certain levels of injury withno economically significant reduction of yield; and insecticides should be used onlyas a complementary method, since the natural biological control is responsible tokeep pests under control. Therefore, the most appropriate timing to initiateinsecticide sprays on soybean fields is thoroughly discussed in this chapter. Thesafety of waiting for 30% defoliation at the soybean vegetative developmental stageor 15% defoliation, when at the reproductive stage, has been proved throughexperiments performed in different areas and with distinct soybean cultivars.Similarly, the economic threshold for stink bugs has already been evaluated throughexperimental field results comparing the use of insecticide when the mean stink bugpopulation of 0.5 insects per sample is found, or when two stink bugs per sample arefound. It can be concluded that anticipating stink bug control on soybean field is anexpensive and excessive practice that only increases the negative impact of thechemicals used in the agroecosystem. Respect for the economic threshold and theoption for pesticides more selective to beneficial arthropods is the clue to thepossibility in reducing the use of chemicals in the agriculture, thus improving itssustainability.THE SOYBEAN CROP SCENARIOThe soybean [Glycine max (L.) Merrill] crop is extensively cultivated in a largeamount of field areas throughout different countries. It supplies half of the globaldemand for vegetable oil and protein (OERKE & DEHNE, 2004) with a worldwideproduction estimated at 256 million metric tons, which illustrates its significanteconomic importance all over the world. Among the largest world soybeanproducers are the United States of America, which produced around 91.4 millionmetric tons during the 2010 crop season, and Brazil, the second largest producer,which yielded approximately 69 million metric tons of soybean during the2009/2010 crop season (USDA, 2010).The global soybean production, however, still could be increased if problems withpests were avoided (OERKE, 2006). Therefore, in order to mitigate the negativeconsequences of pest outbreaks and improve profits, the soybean growers try tocontrol pests with the use of chemicals, an attempt that can rather bring lots ofAcademyPublish.org - The Impact of Pesticides165