Demographic Analyses of Resistance of Five Varietie s of Date Palm, Phoenix dactylifera L. to Ommatissus lybicus De Bergevin (Hemiptera: Tropiduchidae)

Abstract

Demographic analyses of dubas bug, Ommatissus lybicus de Bergevin, (Hemiptera: Tropiduchidae), reared on five date palm varieties (Zahdi, Mazafati, Piarom, Khasi, and Shahani) were constructed under laboratory conditio ns at 27±1ºC, 70±5% RH, and a 14:10 hours (L: D) photoperiod. Data were analyzed based on the age-stage, two-sex life table theory to take the variable developmental rat e among individuals and both sexes into consideration. Results showed that different v arieties of date palm influenced development time and fecundity of dubas bug. The to tal pre-adult developmental time was the shortest on Zahdi (85.21 days) and the long est on Khasi (88.39 days). The longevities of both male and female adults on diffe rent varieties were significantly different. The mean fecundity per female was signif icantly higher on Zahdi (78.62 eggs) and Mazafati (68 eggs) than on Shahani (43.53 eggs) and Khasi (46.32 eggs). The highest and lowest net reproductive rates were obtained on Zahdi (40.58 offspring per individual) and Shahani (16.88 offspring per individual), respe ctively. The intrinsic rates of increase were 0.0401, 0.0368, 0.0355, 0.0312 and 0.0301 per day on Zahdi, Piarom, Mazafati, Khasi and Shahani, respectively. The mean generation time s ranged from 92.78 days reared on Zahdi to 95.25 days on Mazafati. According to resul ts obtained in this study, Shahani and Khasi were the most resistant varieties while Zahdi was the most susceptible variety to dubas bug among the varieties tested. Keywords: Demography, Date palm variety, Dubas bug .