Answer:
The impact of pesticides on soil biota can be either positive or negative, depending on the type of pesticide used. Genetically modified organisms (GMOs) are generally designed in order to be more resistant to pesticides, thereby GMOs might have a higher impact on the soil biota (however, the evidence is not conclusive and case by case should be evaluated)
Explanation:
Traditional chemical pesticides are chemical substances used to control pests (e.g., insect pests affecting corn yield). Examples of traditional chemical pesticides include 2,4-Dichlorophenoxyacetic Acid, DDT, Atrazine, Chlordecone, etc. The impacts of these traditional pesticides on soil biota are variable according to the type of product used, the rate at which these products are applied, the target/non-target soil biota (e.g., bacteria, algae, fungi, protozoa, insects, nematodes). For example, it has been reported long-term contamination of DDT on soil microflora (i.e., microalgae and cyanobacteria), thereby these non-target species declined with increasing DDT use; however, direct effects on fungi populations were not observed. Genetically modified organisms (GMOs) are organisms whose DNA has been engineered by using molecular biology techniques. In crop improvement, GMO plants are designed to be more resistant to chemical pesticides and also to produce pesticides themselves, for example, Bt crops that produce a toxin from <em>Bacillus thuringiensis</em> (Bt) that can kill insect pests. GMO plants can also be designed to be more resistant to pesticides, thereby affecting soil biota at higher scale values. Nonetheless, it is important to highlight that like chemical pesticides, the effects of GMOs on soil biota are also variable depending on the type of GMO, which pesticide GMO is producing, target/non-target soil species, etc.
