The interaction between two individuals in which both individuals gets benefited from each other is known as mutualism. So in mutualism both individual helps each other for their survival. For example in lichens, fungi provide nutrients to algae and algae provide food to the fungal partner.
Here beetles are benefitted because they are getting food by chewing the petals and harvesting nectar but the trees which produce these flowers are not getting benefits as beetles are not dusted with pollens so their genes are not getting spread by beetles to other flowers. Therefore this interaction is not a mutualistic interaction.
