Population Fluctuation and Thermal Requirement for Development of Empoasca decipiens (Homoptera, Cicadellidae) on Different Bean Species in Natural Conditions

Abstract

The leafhopper Empoasca decipiens Paoli is a widespread polyphagous insect pest of several major crops especially bean in Iran and many other parts of the world. Population fluctuation and thermal requirement for development of E. decipiens was studied on four bean species including Phaseolus vulgaris L. (var. Talash), P. lunatus L. (var. Sadaf), P. calcaratus Roxb. (var. Goli) and Vigna sinensis L. (var. Parastoo) in Tehran region, Iran during 2004-2005. In both years, the highest population density of the leafhopper was observed on V. sinensis and on all host plants species, this density increased with increasing temperature and decreasing relative humidity. During two years, the highest and lowest population density of the pest was in early September and late October, respectively. Significantly, the highest and lowest rate of thermal constant related to overall nymph period (max: 288.95; min: 197.43 Degree-days) and overall immature period (max: 473.75; min: 384.05 Degree-days) was recorded on P. calcaratus and V. sinensis, respectively, in which the shortest development time was recorded on V. sinensis (11.59 days for overall nymph and 22.58 days for overall immature). It could be concluded that the host-plant species influence population fluctuation, development time and thermal requirement for development of immature stages of E. decipiens. Thermal requirements can be used to predict the occurrence, development and population dynamics of E. decipiens on different bean species.