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

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 conditions at ۲۷±۱ºC, ۷۰±۵% RH, and a ۱۴:۱۰ hours (L: D) photoperiod. Data were analyzed based on the age-stage, two-sex life table theory to take the variable developmental rate among individuals and both sexes into consideration. Results showed that different varieties of date palm influenced development time and fecundity of dubas bug. The total pre-adult developmental time was the shortest on Zahdi (۸۵.۲۱ days) and the longest on Khasi (۸۸.۳۹ days). The longevities of both male and female adults on different varieties were significantly different. The mean fecundity per female was significantly higher on Zahdi (۷۸.۶۲ eggs) and Mazafati (۶۸ eggs) than on Shahani (۴۳.۵۳ eggs) and Khasi (۴۶.۳۲ eggs). The highest and lowest net reproductive rates were obtained on Zahdi (۴۰.۵۸ offspring per individual) and Shahani (۱۶.۸۸ offspring per individual), respectively. The intrinsic rates of increase were ۰.۰۴۰۱, ۰.۰۳۶۸, ۰.۰۳۵۵, ۰.۰۳۱۲ and ۰.۰۳۰۱ per day on Zahdi, Piarom, Mazafati, Khasi and Shahani, respectively. The mean generation times ranged from ۹۲.۷۸ days reared on Zahdi to ۹۵.۲۵ days on Mazafati. According to results 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