Why do we need to conserve endangered species?

Bees are on the decline and may soon be endangered, the UK have lost 3 of the 19 native species already. An example of the importance of conserving ALL species would be the crises with Asian bees. The bees have been pollinating the pear trees for years. Now due to mive expansion and overkill with pesticides the effect on the bee population has been catastrophic. The huge pear plantations now need to be pollinated by hand. Science blames it of CCD (Colony Collapse Disorder) they put it down to some sort of virus, but like all animals they need a varied diet and with only chemically treated pear tree pollen to satisfy them its inevitable that problems would occur. Please read the link.