Complex sentence: It was reported that studies also identified sub-lethal effects of neo-nicotinoids and fungicides, pesticides that may impair the bee's immune system and may leave the bee more susceptible to bee viruses.
Split into simpler sentences: It was reported that studies also identified sub-lethal effects of neo-nicotinoids and fungicides, pesticides that may impair the bee's immune system. It is hypothesized that these pesticides impair the bee's immune system, which leaves the bee more susceptible to bee viruses.