Chris Packham says 'I'm A Celebrity... Get Me Out Of Here!' is a "grotesque blot" on Ant and Dec's reputation.
The 62-year-old naturalist and BBC presenter has been vocal in his criticism of the ITV reality show over the years amid allegations of animal abuse, and he has called on the hosts to take a stand.
Taking to X (formerly Twitter) this week, he wrote: "I'm A Celebrity... Get Me Out Of Here! remains a grotesque blot on the reputations of both yourselves and ITV.
"Its continued exploitation of animals for entertainment is an anachronistic embarrassment."
He urged producers to "listen to the voices of concern" while pointing to falling viewing figures as "the writing on the wall".
Chris continued: "The cruel exploitation of wildlife for gratuitous entertainment continues to damage the reputation of the UK as a 'nation of animal lovers.' "
He has criticised the show before, but ITV bosses have defended the series and insisted they have done nothing wrong.
A spokesman told the Daily Star newspaper: "As a production, we comply with all laws concerning the use of insects, animals reptiles."
Last year, Chris described the show's approach to animals as "medieval", and branded the old “animals for entertainment” schtick “lazy thinking” and a contrast to what his naturalist work is all about.
In a previous statement after criticism from charity PETA, ITV said: "We are always fully transparent about our protocols and we have a very strict environmental plan in place on the show.
"As a production, we comply with all regional and national laws concerning the use of insects, animals and reptiles.
"Welfare and safety is always the primary priority on any of our programmes, and at any Bushtucker trial that features animals, we have qualified and experienced animal handlers on-site at all times.
"We inform the RSPCA NSW of all of our activities on the show and they have an open invitation to attend the site at any time."