Fungus and fruit consumption by harvestmen and spiders (Opiliones, Araneae): the vegetarian side of two predominantly predaceous arachnid groups

In this review, we report on harvestmen and spiders feeding on fungi, fruits, and seeds. Fungivory in harvestmen is widespread, with most reports referring to tropical species in the family Sclerosomatidae, which consume mainly small forest mushrooms (families Marasmiaceae and Mycenaceae). In contrast, consumption of fungal material by spiders apparently occurs only if airborne spores trapped in the viscid threads of orb-webs (e.g., Araneidae and Tetragnathidae) are ingested along with old webs prior to the construction of new webs. Consumption of fruit pulp by harvestmen is also widespread, with several records of Leiobunum spp. (Sclerosomatidae) feeding on Rubus spp. berries and other lipid-poor fruits in the Holarctic region. In Neotropical forests, harvestmen in the families Cosmetidae and Gonyleptidae feed on lipidpoor pulp of fallen fruits. Among spiders, we document several cases of synanthropic species opportunistically feeding on fruit waste (e.g., pieces of banana, papaya, watermelon, or orange pulp) inside houses or disposed in yards. Only one case of a spider feeding on a wild fruit in the field was found in our search. Finally, we report several cases of harvestmen and spiders feeding on elaiosomes or arils (i.e., lipid-rich seed appendages). In conclusion, harvestmen consume mushrooms, fruit pulp, seeds, and seed appendages more frequently than spiders probably because they are ``solid food feeders'', which means they can ingest solid tissues by biting off small pieces. In turn, spiders are ``fluid feeders'' and feed on vegetable matter most frequently in the form of fluids (e.g., nectar, stigmatic exudate, plant sap, and honey dew), rather than fungal or plant tissues.