I can see my camera device IP on arp -a in command prompt but there is no ARP request detected in Wireshark, why?

edit

arp -a does not cause ARP requests to be sent. It merely reports what's currently in the machine's ARP table, which might be left over from an earlier ARP request.

You could try starting up Wireshark, deleting the ARP entry for your camera device, and then pinging the camera device. That will probably require that your machine send an ARP request to the get the MAC address of the camera device.