Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:In phytophagous arthropods, atranorin was reported to elicit a significant avoidance (Nimis and Skert 2006) or to reduce growth of insect larvae (Pöykkö et al. 2005; Slansky 1979) but no protective effect of atranorin was noticed in snails (Gauslaa 2005; Hesbacher et al. 1995).
Category: