Prevention. Keep the nursery area clean. Millipedes feed on rubbish, decaying leaves, seed shells!! etc. and they prefer damp places. For smaller area's it is sufficient to surround your seedbeds with dry sand or wood ash, to prevent them from entering.
For larger area's chemical treatment with pesticides based on Cypermethrin will do the job
NOTE: THE USE OF ANY RECOMMENDED TREATMENT ON THIS PAGE IS ON USERS OWN RISK AND SHOULD BE ALLOWED FOLLOWING LOCAL LAW AND REGISTRATION. (Actually this is a big problem, since no pest- or fungicides are being specifically registered for Jatropha. Jatropha as a crop is simply too new and only recently got the interest from pesticide manufacturers)