In science, the term "synergy" is used in pharmacology and in ecology.
The term synergy is used when two combined medications have a greater effect than the sum of their individual effects.
The term synergy is used in the same way as in pharmacology, but applied to pesticides or stress agents. For example, studies tested the synergy of an insecticide combined with a pathogen on bees.
Insecticide families work in synergy (organophosphates and pyrethroids, for example). Researchers have realised that when used individually, some insecticides have a reduced effectiveness due to the adaptation of some insects, but when used in combination these insecticides are once again effective.
The term "cocktail effect" is also used.
Some insecticides work in synergy. © bugman50, Flickr, CC by-nc 2.0