A set of web links about the effects of insecticides on bees :-

Two new studies add to the mountain of evidence that neonicotinoids are harmful to pollinators (New Scientist)
https://www.newscientist.com/article/2101308-decline-of-wild-bee-species-in-england-linked-to-pesticide-use/

Europe poised for total ban on bee-harming pesticides (The Guardian)
https://www.theguardian.com/environment/2017/mar/23/europe-poised-for-total-ban-on-bee-harming-pesticides

Strongest evidence yet that neonicotinoids are killing bees (New Scientist)
https://www.newscientist.com/article/2139197-strongest-evidence-yet-that-neonicotinoids-are-killing-bees/

Would we starve without bees? (BBC)
http://www.bbc.co.uk/guides/zg4dwmn

Attack of the bee killers: Documents show Bayer and Syngenta teamed up with farmers to get around bee-friendly regulation (Politico)
https://www.politico.eu/article/europes-lost-colonies-bees-neonicotinoids/

Controversial pesticides can decimate honey bees, large study finds (Science)
http://www.sciencemag.org/news/2017/06/controversial-pesticides-can-decimate-honey-bees-large-study-finds

Farms could slash pesticide use without losses (The Guardian)
https://www.theguardian.com/environment/2017/apr/06/farms-could-slash-pesticide-use-without-losses-research-reveals

Pesticide Lobby Spends Millions To Defend Chemicals Tied To Bee Deaths (Huffington Post)
http://www.huffingtonpost.com/2013/03/29/pesticide-lobby-bees_n_2980870.html