The effect of harmful entomofauna on plant health in the urban horticulture of Zagreb.
Harmful entomofauna was collected in urban green areas of the Zagreb city (avenues, parks, park forests) in Croatia during 2001 and 2002. Collection and identification included 96 species of harmful entomofauna and mites from the following orders: Thysanoptera (1 species), Hemiptera (34 species), Hymenoptera (7 species), Coleoptera (15 species), Lepidoptera (20 species), Diptera (7 species) and Acari (16 species). Harmful entomofauna was gathered on the representatives of 30 genera of woody plant species. Damage incurred by the detected and identified pests was multiple and included defoliation, sap sucking, physiological weakening of trees, drilling tunnels underneath the bark and in the wood, spoiling the aesthetic appearance of plants, affecting proper plant growth and molesters. The most important defoliator and pest of ash avenues identified by this research was Tomostethus nigritus. The most important plane tree (Platanus) pests were sycamore lace bug (Corythucha ciliata) and leaf miner (Phyllonorycter platani). The appearance and health condition of horse chestnut during this investigation was affected by harmful biotic and abiotic agents, of which horse chestnut leaf miner (Cameraria ohridella) was one of the more important. Aphids from the supra-family Aphidina were represented by 23 species. The harmful nature of these species in the study area was primarily manifested in the molester effect. Mites were represented with 15 species. According to the research, city avenues and parks are sites with simplified natural processes in terms of plant diversity and the host-natural enemy interaction. Consequently, the population dynamics of harmful insects in such anthropogenic conditions differs profoundly from that in the natural environments.