> My understanding is that defensiveness is a complex trait

Agreed. It's also what's called a "poly-genic" trait, one which is controlled by many different "genes." 

However, acute sensitivity in any one of the traits could lead to hyper-defensive bees. 

For example, overproduction of venom, leading to colony being alarmed more quickly, or hypersensitivity to odor, same effect.

PLB

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