Relatonbetween orchid ophrys and bumble bee is eg. of mutalism or commensalism.

The relationship between the orchid Ophrys and bumble bee is mutualism. The orchid Ophrys employs sexual deceit to get pollinated by bumble bee. One petal of its flower bears a resemblance to the female of the bumble bee in size, color and markings. The male bee is attracted to the petal perceiving it a female, pseudocopulates with the flower and in that process pollinates the flower.  
It is an example of mutualism because the bumble bee gets reward in the form of pollen and nectar while the plant gets pollinated.