WP_Widget constructor method deprecated in virtue theme widgets.php

As the error says, your have deprecated function.

1. Make sure All your Plugins are Up-to-date, if not update them first
2. Deactivate all your existing plugins and see if the issue still persists
3. If not, start activating plugins one by one and keep checking from which particular Plugin the error is being raised. If you find the culprit and if it is a Plugin that your installed, contact the plugin developer with the issue.

The following links might be helpful. They are addressing your exact issue:

http://docs.layerswp.com/doc/notice-the-called-constructor-method-for-wp_widget-is-deprecated-since-version-4-3-0-use-__construct/

and

https://stackoverflow.com/questions/32860218/the-called-constructor-method-for-wp-widget-is-deprecated-since-version-4-3-0

Let me know if this helps!