The Bumblebee Ecological Protection and Preservation State

Bumblebees are Among
Some Parasitic Specie

Source
Wikimedia Commons

Unfortunately there are some "bumblebee" between parasite species and therefore are not productive in pollination processes for farmers.

So it is not uncommon for employers of agricultural and agribusiness, large- cale use of pesticides in order to reduce or extinguish the population mass of these parasitic species of bumblebees, however and yet so far but with a purpose to protect their crops, often drastically alter the populations of bumblebees parasites and even pollinators, gaping a remarkable ecological imbalance then began to decline and even certain plant species disappear due to indiscriminate use of pesticides. 

Bumblebee Asocciation - The Bumblebee Ecological Protection and Preservation State

That is why in the UK the association was founded: "Bumblebee Conservation Trust", whose main objective is to protect and encourage the conservation of all species of bumblebees especially in those that are in danger of extinction. However, despite the joint efforts, many species of bumblebees have disappeared, hence a constant concern for the species occurring in danger of extinction because its destruction would result in a major ecological imbalance that would not only affect but also Hymenoptera other floral and even food species. 

It should be noted and mentioned that due to the massive use of some pesticides have disappeared not only some species of bumblebees in the U.K., but also in America.

In my personal opinion I think you should study further the use or implementation of methods of natural pest control so as not to create ecological imbalances as marked and/or permanent in the short, medium and long term would have serious and undesirable consequences not only for different species of bumblebees but for all wildlife and captive.