TV presenter Chris Packham has penned an open letter to Ant and Dec - calling for the pair to step in and end the "abuse of animals" on I'm A Celebrity... Get Me Out Of Here!.
The ITV jungle show returns on Sunday with a new line-up of celebrities, including Allo Allo! actress Vicki Michelle and former motorcycle world champion Carl Fogarty, facing spiders, snakes and cockroaches in the bushtucker trials.
Springwatch host Packham, 53, described the trials as "barbaric" and "silly" and said that the hit show was undoing the work of natural history programmes.
In the open letter, published in Radio Times magazine, he said that t eaching young viewers that killing for "exploitative 'entertainment' is acceptable" is "a shame that I imagine neither of you will want to take to your graves" .
Packham wrote: "Could I please ask you to reconsider the use/abuse of animals in your popular and otherwise entertaining show, I'm A Celebrity... Get Me Out Of Here!?"
The presenter said that the trials "undermined a respect for life, which ... impacts negatively upon conservation ... and ... spoils the show because it's simply out of date, some would say barbaric."
He added: "It's often pretty silly too, because many viewers recognise that the species used are not dangerous, or significantly toxic or venomous in the first place. Or that they've been 'doctored', their fangs sealed, their jaws bound so, even under the stress they're exposed to, they couldn't possibly harm any of your guests."
Packham told the duo: "But then, let's face it, as we all know, you couldn't let that happen anyway. It's a sham."
He wrote: "The problem is that animals such as snakes, spiders, crocodiles, rats and many invertebrates are already misunderstood and thus unfortunately vilified, despite the incredibly important roles they play in the world's ecosystems and our lives.
"By orchestrating a fear of them among your contestants, I'm afraid you're reinforcing and exaggerating a terrible ignorance and intolerance of these remarkable animals."
He wrote: "What particularly frustrates me is that this counters and undoes all the education that I and my colleagues strive to achieve in our natural history programmes.
"Lads, it's not all about the cute and the cuddly; every species plays a role and until we can all see the importance of this, we won't make the urgent progress we need to in conservation."
He said of the ITV show's large audience: "Just imagine getting them all to respect these creatures rather than continue to be unnecessarily revolted by them. Surely that is something you could be genuinely proud of?"
Packham dismissed I'm A Celebrity's use of consultants to advise on animal welfare, saying: "I can guarantee that some animals are harmed during production, because they are fragile or easily stressed. Or simply killed, as they are in your Bushtucker trials."
He criticised the "mockery" of insects being eaten on I'm A Celebrity... when in some parts of the world "invertebrates are routinely eaten without repulsion - normally because there is no choice".
The presenter accused the show of teaching "younger viewers ... that killing things for plain exploitative 'entertainment' is acceptable."
Packham added: "I'm sorry, but that is a shame that I imagine neither of you will want to take to your graves, because I assure you that your grandchildren will not thank you for it.
"The show has been running for years now. Surely it's time for it to mature, for you to accept that, as pillars of the British broadcasting community, you should put an end to this inhumane, embarrassing and destructive aspect of an otherwise great show."
ITV responded to Radio Times, saying: "Ant and Dec are the presenters of the show, and as such are not involved with the formatting of the trials, which are devised by the show's producers.
"ITV takes animal welfare very seriously and expert handlers are on hand at all times."