An Experimental Test of Lanchester’s Models of Combat in the Neotropical Termite Nasutitermes corniger (Blattodea: Termitidae)

Lanchester’s models of combat have been invoked to explain the mechanics
of group fighting in social animals. Specifically, Lanchester’s square law
posits that the fighting ability of the group is proportional to the
square of the number of combatants. Although used to explain a variety of
ecological phenomena, the models have not been thoroughly
tested. We tested the Lanchester models using group battles
between colonies of the termite Nasutitermes corniger. Our main goals were
to determine if mortality rates fit the Lanchester models, and if so,
whether the behavioural mechanisms underlying a group’s success match
those used in deriving the model. We initiated battles between pairs of
colonies with different ratios of fighters and recorded deaths over time.
We found that the numerically larger army has an advantage, but that the
advantage is not as pronounced as predicted by Lanchester’s square law. We
also video-recorded battles to analyse individual behaviour, which did not
support the mechanisms invoked by Lanchester. Instead, the killing power
of an individual is increased by the presence of nestmates, giving the
larger group a disproportionate advantage. Although the behavioural
mechanisms leading to the advantage may differ, our results still support
some of the proposed ecological phenomena.