  In this paper, we provide a pathwise spine decomposition for multitype
superdiffusions with non-local branching mechanisms under a martingale change
of measure. As an application of this decomposition, we obtain a necessary and
sufficient condition (called the $L\log L$ criterion) for the limit of the
fundamental martingale to be non-degenerate. This result complements the
related results for superprocesses with purely local branching mechanisms and
in Kyprianou and Palau (2016) for super Markov chains.
