A thread about disinsection spraying from earlier this year (even with a report or two about spraying on EU flights) with links to requirements:
​​​​​​https://www.flyertalk.com/forum/brit...-take-off.html

Disinsection requirements are set by each country, including whether the spraying must be done while passengers are on board. Some countries allow for a more robust fogging that can at last for several weeks (which eliminates the need to spray during each flight).