Effect of climatic and management factors on the abundance of dubas bug, Ommatissus lybicus Bergevin (Hem.: Tropiduchidae) in northern Hormozgan and southern Fars Provinces

The dubas bug, Ommatissus lybicus Bergevin, is one of the most important pests of date palm, Phoenix dactylifera L. in several countries in the Middle East such as Iran and North Africa. In this study, the effect of climatic and crop management factors were investigated on the density of dubas bug in north of Hormozgan and south of Fars Provinces during 2010-2011. Correlation and factor analysis were used to determine the relationship between dubas bug density and management factors. Correlation analysis between pest density and management variables showed that in most studied regions, there were positive correlations with variables such as age and height of date palms, mixed cultivation with citrus, application of fertilizers, yellow wasp (Vespidae) population, intensity of weeds and number of date palm leaves, and negative correlations with variables such as irrigation period, application of pesticides, mites and scale population and distance between date palm stands. According to the results of factor analysis, seven factors explained 74.68 percent of total variance. To evaluate the impact of these factors on the population density of dubas bug, the multivariate regression was used. The results showed that the factor which included variables such as wall around the palm orchards, yellow wasp population and distance between date palms had the most contribution to prediction of dubas bug density. The second and third most contributing factors in prediction of pest density were factors which included variables such as collecting the pruned leaves and intensity of weeds, and variables such as irrigation period, age and height of date palm, number of leaves and intercropping with citrus, respectively.The highest nymphal density of the pest on date palm leaflet was observed in Farashband followed by Forg, Hagiabad and Jahrom regions, respectively. Among the weather factors, hourly solar radiation and relative humidity had negative and positive association with dubas bug density, respectively.