In my view:
'' Antivirus for android is a myth,'' there is no need to use if you are careful, and only download the official store Play Store, and leave off the unknown sources. Rather than invest in antivirus for android would be a good anti theft, as exemplified by Cerberus. They analyze only for android Antivirus detection signatures with the supposed'' malware''. Mobile companies AV make very '' noise'' to sell their products ..
Root should also be careful. Android is based on Linux, read permissions of applications and be happy