Yo Ogre ,
This is the Captain Down Under ,
Insulation has many forms . I have experimented with cold prevention through 1. Aaspect
2. wind breaks and barriers .
3. Hot bedding the soil surrounding the hives
4. Insulated bee hives .
5. placing a nuke hive on top of a strong hive with different entrance directions .
Given we do not have snow I have no experience there other than logic / intuition tells us that controlling the environment should help or hinder the bee colonies .Look to nature and study the success of wild bees and use this as a guide to success . Barns , House roofs and cavity's -Hollow trees and upturned bins seem to work . We have Eucalyptus trees that produce great hollows . The bees favor hollows with smallish near vertical entrances .
The insulated effect both summer and winter is often profound .
My opinion is that bees will divert the necessary resources to keep warm and there young alive .The harsher the conditions ,the more resources will be consumed in survival . The population could diminish further if food is scarce ,weather is adverse and disease is present . Death of a thousand cuts !
It is up to us to thoughtfully intervene when pesticides are sprayed in the foraging area . Likewise add food when there is a dearth . Locate your hives out of the prevailing winds , angle the entrance downward to encourage condensation to drain , install top entrances if need be . face the entrances toward the rising sun Go for insulation ? Although you may not need to if other measures suffice .