*2.1.3. Microbial control*

Viruses, bacteria, and fungi have also been used against pests of maize. Especially for *H. armigera* control, in the literature, although they mention the use of baculovirus, they highlight the increase use of *Bt.* The control efficiency with microorganism depends largely on the period and the application technique because caterpillars cannot be protected within the ear.

In Brazil, there is a great experience in using baculovirus to control fall armyworm. In other countries, a commercial product based in nuclear polyhedrosis virus (NPV) already exists, such as, for example, in the USA, to control *H. zea* and *H. armigera*. To achieve success in the control ear pests with virus, the product must be applied in order to hit the target, both for the attack location as compared to the caterpillar development stage, which cannot be greater than 10 mm in length.

Similarly to the virus, maize ear pests can be controlled by the *Bt*-based products. However, the efficiency of the products depends essentially on adjustment of the solution volume (liters of spray solution/ unit area) that can be evaluated by the use of sensitive papers which should obtain a minimum number of 30 drops cm-2.
