ngdes

Project Designs

This is a study of leaf-chewing herbivores feeding on 62 of the common tree species in the lowland forests of the Madang area: 16 species of Moraceae (including 15 Ficus spp.), 15 of Euphorbiaceae (6 Macaranga spp. and species from 9 other genera), 16 of Rubiaceae (4 Psychotria spp. and species from 12 other genera), and 15 species from other 15 plant families. Insects were hand-collected from the foliage of the target plants and all host plant records verified by feeding tests. Numerous ecological variables of the host plants were measured in the field. The study included 74,118 herbivorous insects from 1,092 species, feeding on the 62 host plants studied. Analyses of this data set highlighted patterns of host use, as well as the host determinants of insect species richness.

This study is planned as an extension of the detailed research on diversity and host specificity of herbivores in the Madang area to other major lowland areas of Papua New Guinea. Caterpillars feeding on hosts from 9 genera (Dysoxylum, Ficus, Gnetum, Hydriastele, Macaranga, Myristica, Pometia, Psychotria and Pterocarpus) will be studied at 8 lowland sites from two major lowland areas, the ancient southern lowlands on Australian Platform and the historically recent and heterogeneous northern lowlands, isolated from the south by a central cordillera. In the North, 3 sites will be located in a terrane, recently accreted to New Guinea, while 2 sites will be in older terranes. Caterpillars will be hand-collected from the foliage of the target plants, their hosts verified by feeding tests, caterpillars digitally photographed and reared. This study will document patterns of beta-diversity of herbivores and their hosts in lowland rain forests on the scale from 120 to 350 km.

This project studied Auchenorrhyncha (Hemiptera) on 15 species of Ficus, targeted also by the study of leaf-chewing insects. The sampling of both herbivore groups is simultaneous, but no feeding tests are performed for the sap-sucking species. Analyses of the 61,777 insects from 491 species focused on species richness, host specialization and seasonality of species from the phloem-, xylem- and cell-feeding guilds of the sap-sucking insects, as well as on the comparison with the leaf-chewers.

Ecological and phylogenetic studies are aimed at understanding the evolution of interactions between the dioecious figs, Ficus subg. Ficus, (Moraceae) and 78 species of their associated wasps (Hymenoptera: Agaonidae).The focus of these studies is Papua New Guinea, a center of diversity and endemism for the dioecious figs.

Using the pyrethrum knockdown technique (canopy fogging), the insect fauna associated with several forest trees, especially in the family Fagaceae, was studied along altitudinal transects near Wau. Many samples focused on the tree Castanopsis acuminitissima in mid-montane rain forest and the analyses have so far emphasized the beetle fauna.

Using a wide variety of techniques, including interception traps, canopy fogging, clipping, hand collecting and beating, the insect herbivores associated with ten species of trees belonging to unrelated plant families were studied at mid-elevation near Wau. The emphasis was on leaf-chewing insects and this allowed testing insect host specificity in the laboratory. Analyses contrasted the species richness, host specificity and similarity of leaf-chewing insects among host-trees.