Arduino MEGA ADK: read data from usb(not serial)
Looking at the datasheet and a page I found by google searching for "TELOSB mote platform", it appears the TelosB module uses an FTDI USB to serial chip for communications.

The Arduino USB host library has support for these chips and contains an example for using them. You could modify it to read/write whatever data you're looking for.

However that's a pretty roundabout way of getting data from the TelosB; your Arduino would be talking to a USB host sheild, which would talk to a FTDI chip, which would talk to the UART on the TelosB's onboard micro-controller.

It would be easier if you could find a way to connect the Arduino's UART directly to the onboard micro-controller's UART. Then you could use standard Arduino serial comms to get data from the TelosB. Level conversion may be required if the UARTs on the Arduino and the TelosB run at different voltages.

It is possible one of the two expansion headers on the side of the board connect to the micro-controller's UART. The datasheet doesn't provide this infomation, you'd need to look at a schematic of the board or a pinout description.