THE FUTURE VISIONS AND THE INFLUENCE OF CLIMATIC FACTORS ON THE SPATIAL DISTRIBUTION OF DUBAS BUG OMMATISSUS LYBICUS (DEBERGEVIN) ON DATE PALM TREES IN IRAQ
Date palm trees and fruits are subjected to infestation by many serous pests causing a big decline in date production and quality. Infestation distribution and severity are varied according to kind of infestation and species of the pest along with the governing environmental factors. The dubas bug Ommatissus lybicus (Debergevin) is considered as a key pest attacking date palm trees mostly in the central region of Iraq. This pest was almost absent in Al-Anbar Province during the past years, however, field survey conducted in different regions of this province during spring and fall seasons of the year 2007 indicated the presence of dubas bug on date palm trees in some orchards toward the east of Hit city. The second generation of the pest was the most damaging in terms of affected trees and accumulation of honey dew. Scattered infestations were also recorded in some orchards west of Hit city toward Al-Qaim at the upper Euphrates regions. Since the spread of this pest occurred in a discontinuous manner with no correlation with closely infested Provinces, this study was initiated to explore the limiting factors influencing the spatial distribution of dubas bug in Iraq with special emphasis on Al-Anbar Province. Results indicated that the mean insects density was 40 nymphs/leaflet recorded during hatching time, at the last week of April and early May of 2008 , reduced to less than 5 nymphs/leaflet during the third week of May of the same year .This reduction was attributed to the severe winter of 2008 in which the minimum temperature dropped below zero in Al-Anbar Province for several days causing the death of date palm leaves in many orchards and resulted in harmful effects on dubas eggs inserted in these leaves. The continuous occurrence of dust storms was another factor which had harmful effects on moving stages. The reduction of dubas infestation to non-damaging levels was continued during spring and fall generations of 2008 and 2009 as a result of the indicated climatic factors. Insects were mainly found on offshoots near the ground with a density ranging between 1-15 individuals/tree. Results have also indicated that the arrival or transmission of the pest to some regions of Al-Anbar Province happened in a way other than the normal distribution due to the limiting climatic factors, therefore, this pest may not persist in the region for a long time. The population might be reduced to non-damaging levels or even disappear during the coming few years. A reliable monitoring system is essentially needed in order to keep the pest under control within a comprehensive IPM program against date palm pests in the country.
Ali, A.-S.A. (2010). THE FUTURE VISIONS AND THE INFLUENCE OF CLIMATIC FACTORS ON THE SPATIAL DISTRIBUTION OF DUBAS BUG OMMATISSUS LYBICUS (DEBERGEVIN) ON DATE PALM TREES IN IRAQ. Acta Hortic. 882, 929-935
date palm hopper, Al-Anbar, dust storm, Euphrates, hit, new spread