Director: Center of Biological Control & IPM, Faculty of Agriculture, Cairo University, Egypt

Abstract
The previously existing natural balance since thousands of years among fauna and flora in the natural desert ecosystem in Egypt was obviously disturbed by intervention of man reclaiming land for growing monocultured large areas. This intervention led to changes in many food chains resulting sometimes to be in favor of certain insect species to flourish on such monoculture and develops into devastating economic pests. The emerged problem of the rose shafer, Tropinota squalida Scop. (Scarabaeidae : Coleoptera) in the newly reclaimed desert land as serious economic pest on deciduous fruit plantations in the North of Egypt is a classic example for such intervention. On one side, man removed the desert perennial wild flora which produces flowers in spring being the only food for adults of this univoltine scarabaeid insect; and instead man planted economic plants giving their flowers also in spring offering huge amounts of food for this shafer. On the other side, the heavy agricultural machines destroyed the ground nests of the desert insectivorous shrew Crocidura (Ord. Insectivora; Fam. Soricidae) which is the main natural biocontrol agent suppressing population of T. squalida along the year in the Egyptian desert ecosystem. Thus, by time T.squalida built up high populations causing high economic losses reaching 80-90% in some areas. Rebuilding up Crocidura populations by preservation methods, took 20 years to reach the natural balance level between the pest and its main concerned natural enemy.

Taking the case of T. squalida into consideration, the recently emerged problem of the thrips Dendrothrips eremicola Priesner (Dendrothripidae) as newly devastating pest to olive trees in the reclaimed desert land in Egypt, has similarly been slowly started since intervention of man to construct large areas of olive groves as monoculture without entomolgical concern within biodiversity in such a stable ecosystem. The Oleaceae wild desert flora, Ligustrum ovalofolium, L.privit and Syringa sp. are the natural host plants for D. eremicola in the desert ecosystem in Egypt. By land reclamation, man applied different agricultural practices for creating the new agroecosystem; among which removal of the limited amounts of wild flora hosting this thrips; and instead offering the insect large areas of another food source,i.e., the economic Oleaceae species Olea europeae. The slight similarity between damage symptoms of sand storms on olive leaves and those caused by infestation with this thrips was a very important factor contributed in covering up the developing problem for years, where the olive growers considered both as one, and correlated it simply to the usually known sand storms in the area. Following the international literature, this is a unique case of olive man-made pest problem found only in Egypt recording D. eremicola as a key pest for the first time attacking domestic olive resulting from disturbing the natural biodiversity.