Android gradle: how to run separately integration and unit tests?

Currently I have standard structure of project:

src

|---androidTest

|-------------------|---java

|----------------------------|---robotium

|----------------------------|---unit

|---main

|---------|---AndroidManifest.xml

|---------|---java

|---------|---res

According to documentation

I've placed unit and integration tests under androidTest folder.

Since instrumentation tests need lot of time, I placed it inside robotium folder(I use Robotium). Inside unti - jUnit tests respectively.

To run all tests I invoke ./gradlew connectedCheck - it's taking lot of time.

How to to run integration (inside robotium folder) tests and unit tests separately? I want to run these tests using gradle - it's for CI server. For example I want to run integration tests every night and unit tests - every hour..

Thanks!