The Impact of Pesticides - Academy Publish

Means followed by the same letter in the column are not statistically differentbetween each other by the Tukey test (P>0.05); 2 Original results followed by thestatistics performed on data transformed by X (this data indicated the percentage ofseeds with dead embryo due to stink bug injury).Currently in Brazil, the infestations with stink bugs have increased significantly onthe soybean crop and this is especially true with the species Euschistus heros(Hemiptera: Pentatomidae) (BUENO et al., 2007). This has occurred due to acombination of factors such as: 1) selection of resistant populations of stink bugs tothe main insecticides used; 2) Low number of insecticides with differentmechanisms of action; 3) deficiencies in the application technology of theseproducts; and 4) ecological imbalance caused by the abusive and disordered use ofbroad spectrum insecticides, early in the development of the culture (BUENO et al.,2011; CORRÊA-FERREIRA et al., 2010). Therefore, the increased use ofinsecticides on the soybean fields will only contribute to aggravate the problemscited. Thus, similarly to the previously mentioned for defoliators, also for the stinkbugs complex the overuse of insecticides brings more harms than benefits,especially when considering that there is no indication that the recommendedeconomic threshold of 2 stink bugs ≥ 0 5 cm/meter is not safe to ensure the yieldassociated to the sustainability of the culture.In the results obtained in that experiment, the observed productivity differed only inrelation to the control treatment with no difference in productivity among the othertreatments (Table 2). By analyzing the quality of the grains it can be observed thatthe damage from stink bugs (scale of 6 to 8, which means the % of seeds withembryos killed by the stink bugs) in the tetrazolium test, the result was statisticallydifferent only for the control treatment that had 13.7% of the grains with deadembryos. The treatment 1 (economic threshold recommend for stink bugs); 2 (1/4 ofthe economic threshold for stink bugs); and 3 (use of insecticides in combinationwith herbicide and fungicide) were statistically similar and showed percentages ofseeds with dead embryos lower than 6% (Table 2). Such intensity of damage (6%)is still allowed, even in the category of soybean for seed production, which is morerigorous than the experiment performed, which was carried out in a soybean fieldaimed to grain production.Thus, it is safe to affirm that controlling preventively the stink bugs [in the exampleused: treatment 3 (with four insecticide applications); and treatment 2 (¼ of theeconomic threshold recommended for stink bugs, with six insecticide applications)]is not feasible, mainly for not providing significant benefits on productivity orquality of the output attained, besides greatly increasing the number of chemicalapplications and consequently the production costs and the negative impact of it onthe environment. On the contrary, the treatment which waited until the economicthreshold level recommended for stink bugs had been reached, in addition to thereduction of environmental risks showed a practical and easily measurableadvantage, which is the lower production cost due to the lower use of chemicals.Therefore, the chemical application at the right moment can be considered the mostsustainable treatment among all the different management practices evaluated andmust always be adopted by growers to reduce the negative impacts caused byagricultural chemicals in the environment since it rationalizes the use of pesticides.AcademyPublish.org - The Impact of Pesticides176