Complex sentence: Attempts to prevent RRSV infections by controlling BPH with insecticides often have the opposite effect of facilitating RRSV outbreaks; this can be due to a disproportionate effect of insecticides on the natural enemies of BPH.
Split into simpler sentences: Attempts to prevent RRSV infections by controlling BPH with insecticides, often have the opposite effect of facilitating RRSV outbreaks. This can due to a disproportionate effect of insecticides on the natural enemies of BPH.