In Forests and Insects: 18th Symposium of the Royal Entomological Society(eds A. Watt, N.E. Stork & M. Hunter). Chapman & Hall, London, Pp.341-361.

Ficus: a resource for arthropods in the tropics, with particular reference to New Guinea



Yves Basset, Vojtech Novotny and George Weiblen

Abstract

We summarize the records available worldwide of 1875 species of arthropods feeding on Ficus (Moraceae), including 742 species feeding on syconia,481 sap-sucking, 369 leaf-chewing and 283 stem/wood-boring species. Some preliminary data from a local study of Agaonidae, Auchenorrhyncha and leaf-chewing insects feeding on 15 species of Ficus in Papua New Guinea are presented.The literature and the field data suggest that the most speciose taxa feeding on Ficus include (a) representatives of some rather polyphagous families, such as certain Cerambycidae, Aleyrodidae, Coccidae, Pseudococcidae, Aphrophoridae,Bostrichidae, Lymantriidae and Noctuidae; and (b) some specialised taxa,such as certain Agaonidae, Drosophilidae, Curculionidae and Tephritidae, feeding internally on syconia; Homotomidae feeding on phloem; certain gall-making Phlaeothripidae feeding on mesophyll; and certain Choreutidae, Nymphalidae, Crambidae, Bombycidae and Noctuidae, feeding on leaf tissues. Further, the present field data (consisting of almost 12,000 individuals representing 440 species) suggest that, at a higher taxonomic level, the local composition of the insect fauna feeding on New Guinean Ficus appears to be similar to that feeding on Ficus elsewhere, with two differences: (1) since New Guinea represents an area of considerable diversity and endemism for Ficus, its associated leaf-feeding fauna may be more diverse there than elsewhere; and (2) fig wasp assemblages exploiting monoecious figs may be more species-rich than those exploiting (gyno)dioecious figs, which are prevalent in New Guinea. The field data also suggest that (1) leaf-feeding insect species restricted to particular Ficus species are rare; and(2) some Ficus species which support many species of herbivorous insects are not particularly attractive to frugivorous vertebrates. Thus, the keystone-species concept is difficult to substantiate for Ficus-feeding insects in our study area and, further, cannot be applied across different guilds of consumers.