I'm not sure how old you are and if you'd remember, (as noted in previous post too) however not that many years ago on international flights when you arrived the hosties walked down the isles with their cans of fly/bug spray polluting the interior. I believe nowadays they simply inject the spray into the air conditioning system on descent which is one of the reasons why people often start coughing on descent. Would be I interested to know if this is still in use though?
VH-XXX I have never heard of such a system.
Current policy is for aircraft to be sprayed during regular maintenance using a long term surface spray by approved personel which is then valid for a period of up to 8 weeks . A Residual Disinsection Certificate is then carried on board the aircraft and is provided to the appropriate Quarantine authorities electronically. The details of the Disinsection are confirmed by the PIC via the Gen Dec on arrival.
If the Certificate is not current then Quarantine will board the aircraft and conduct the manual spray that you have mentioned.
Either way it is a very good reason not to use the "5 second rule" on board an aircraft when considering eating a dropped jelly bean!
http://www.daff.gov.au/__data/assets...procedures.pdf