The Impact of Pesticides - Academy Publish

Figure 4. Illustration of the consequences from the wrong insecticide use (nonselectiveproduct or the abandon of Economic Thresholds = spraying at the wrongtiming) endangering Soybean-IPM sustainability in analogy to a house roof (adaptedfrom GALLO et al. 2002).Therefore, aiming at mitigating the harmful effects that can be caused by pesticides,the adoption of the Soybean-IPM with the use of selective pesticides to beneficialinsects (and less harmful to the environment) sprayed only when necessary (at levelsequal or above the recommended economic thresholds) is of crucial importance.Economic ThresholdsThe IPM is based on the premise that crop plants can tolerate certain levels of injurywith no economically significant yield reduction (HIGLEY & PETERSON, 1996).In this context, STERN et al. (1959) defined the lowest pest population that is ableto cause economic damage to plants as the Economic Injury Level (EIL). However,to avoid reaching the EIL and the consequent losses on productivity, several factorsshould be taken into consideration, such as the time needed for the control measuresto become efficient against the pests, or climate factors that can delay theimplementation of a control measure, among others. Therefore, the decision ofwhether or not to control a pest population should always be made before the EIL isreached. The appropriate time to start the control measure in order to prevent thepest population from reaching the EIL is termed the Economic Threshold (ET)(PEDIGO et al., 1986). Therefore, insecticides should not be preventively appliedon the soybean crop and their use is only justifiable when the pest population isequal or higher than the recommended ETs (Figure 5).AcademyPublish.org - The Impact of Pesticides170