Sentence:  "Secondary parasites", or <WSD>"hyperparasites</WSD>", are parasites of primary parasites and have quite the opposite ecological effect since they constrain the population of the primary parasite. [...] A few species are able to function as "facultative <WSD>hyperparasites</WSD>", attacking both the host and its primary parasites. 
Meaning of the word marked with <WSD> tags:  An insect that parasitizes another parasitic insect.