Build-Depends?

[Michael Vogt <mvogt@acm.org>]

Dear Debian-Mentors

I wonder, why my "Build-Depends:" Field is ignored by dpkg-source and
dpkg-buildpackage ? I added the "Build-Depends" to my debian/control like
this:
-------------------------------8<-----------------------------------
Source: bsd-ftpd
Section: net
Priority: extra
Maintainer: Michael Vogt <mvogt@acm.org>
Standards-Version: 3.1.1
Build-Depends: libwrap0-dev

Package: bsd-ftpd
Architecture: any
Depends: netbase, libpam-modules, ${shlibs:Depends}
Provides: ftp-server
Conflicts: ftp-server
Replaces: netstd
Description: FTP server
 This is a port of the OpenBSD ftp server. 
---------------------------------8<-------------------------------
If I build the package without libwrap0-dev, dpkg-buildpackage
does not complain. But the build fails (of cource).

Did I something wrong ?

best regards
 Michael

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