The BBC reports that northern England is currently under attack by exploding zombie caterpillars.
From the report:
Caterpillars are being killed by a bug which turns them into "exploding zombies", a wildlife expert has said. Lancashire, Manchester and North Merseyside Wildlife Trust said the skins of insects have been found on Winmarleigh Moss, near Garstang.
The caterpillars usually eat heather and bilberry but are being infected by a baculovirus which causes them to seek light so they climb up trees where they explode and the baculovirus is released to seek new hosts.
Fortunately higher animals such as humans are immune from such things ... or not!
It's not clear if the "trick" of the virus is to get it to climb high up to be heated by the sun in order to explode (releasing virus copies), or if the virus causes it to directly explode and it's high up to spread further (spray wider before hitting ground), or being high is to be seen and eaten by birds so that birds spread the virus, or combo. If the purpose is to get eaten by birds, then exploding is not necessary, and thus may be a side-effect of being high (too much sun). Thus, what role do birds and sun play, if any? Birds were mentioned in passing only.
what role do birds and sun play, if any?
None.Scientists have replicated this phenomenon in a laboratory setting. I forget if they identified which viral proteins are responsible.
The viral protein necessary is known:https://www.ncbi.nlm.nih.gov/m/pubmed/25443568/ [nih.gov]
What! You're actually imputing purpose to evolution?