Palomena prasina with berry-belly(?)

Inspired by a comment exchange with Christine I dug up some old images of a discussion about food possibly influencing the colour on the belly of this Green shield bug. I'm a bit dismayed at the poor quality of the old photos (all between 2006-2008), but they still show the cause for discussion/doubt, so hey ...

When I found this here bug (photograph above), I was convinced the pink belly would have been caused by the diet of reddish-purple berries it was sitting on. The colours just seem to match perfectly.

This image was taken on September 3rd. We had a short discussion on this on waarneming.nl (a Dutch biodiversity platform) and it was suggested that the colour could very well be "just" the beginning of this animal's change to winter colours.
Indeed, in this process the belly usually seems to "go" first with many brown "freckles" appearing, just around the same time in September. To illustrate this, here are two images of September 10th and 18th both from a different location than the one above, where there are no red berries present, so in this case the colour is the onset of winter colouring, I'm sure.

September 10th, this one is already changing to winter dress:

September 18th, this one is still celebrating summer:

Just for comparison, here is a collage of "full" winter colours, taken in France in February:

All in all, I still think the pink on the first image matches too darn well with the berries, but given that this was in September and these critters do start getting brownish speckled bellies around that time I can't be sure ... possibly still a combination of the two?!?