Arthropod communities of Proteaceae with special emphasis on plant-insect interactions

[摘要] ENGLISH ABSTRACT:Arthropod communities of five proteaceous species viz. Protea repens. P. neriifolia. P.cynaroides,Leucospermum cordifolium and Leucadendron /aureolum were studied. A faunal list of the insects wascompiled according to the feeding guilds of insects. Six phytophagous guilds were recognized: flowervisitors, thrips, endophages, ectophages, sap-suckers, and ants. The guild composition, species packing andseasonal distribution for the free-IMng insects, spiders and other arthropods were investigated on thedifferent plant species. The ants, flower visitors and sap-sucking species found on the plant species, werevery similar, but the number of leaf chewing species common to all the plant species was low, suggestingthat some species were monophagous. Insect abundance increased during the wet winter months when theplants were in flower. Of the total number of herbivores collected, flower visitors represented 69,5%, leaffeeders 14,5% and sap-suckers 16,1 %. The chewers constituted 60,1% of the total herbivore. biomass. Leafdamage increased with age ; young leaves were practically free of herbivore damage, while older leaveswere stm acceptable as food. The degree of insect damage differed amongst the plant species varying from2% to 15%. The following leaf characteristics were investigated to determine the factors involved in defenceagainst insect herbivory : total phenolic content, protein precipitating ability, cyanogenesis, nitrogen content,leaf toughness, woodiness and fibre content lt appears that the plant species use different mechanisms toprotect their leaves. The infructescences of Protea repens were exploited by the larvae of four Coleopteraand four Lepidoptera species. The community structure of these phytophagous insects was determinedlargely by negative interactions. Various strategies are followed (e.g. niche segregation in time and space)to lessen interspecific competition.

[发布机构] Stellenbosch University