Bugs eating away my plant roots

Hi
We planted some fruit and drumstick trees and have pest problem, I think its called white grub, white body with brown heads. The birds love to eat them and they are filled with gooey fliud. These bugs are underground and they are eating away the roots and in some cases cut the stem at the base.
Please suggest organic ways to control these bugs. I also have good  numbers of earthworms near the root zone, so dont want to kill them also by using chemicals. I had used Neem Cake during planting but its one month now.
Please let me know.

Thanks
Nikhil

you can use Metarhizium anisopliae
you can get from
drrajanlaboratories.com/product8.html

or
abtecbiofert.com/

or

phaladaagro.com/contact-us.html

you can also refer thread farmnest.com/forum/agricultural- … 4/#msg2674

Thanks will contact these people.

Nikhil