How Different Populations and Host Plant Cultivars Affect Two-Sex Life Table Parameters of the Date Palm Hopper, Ommatissus lybicus (Hemiptera: Tropiduchidae)

Abstract

Worldwide distribution of the Date Palm Hopper (DPH) , Ommatissus lybicus de Bergevin along with intensive regional chemical and cultural practices to control this pest provide a basis for development of high genetic div ergence. This genetic divergence can result in demographically distinct populations. In this study, the demographic parameters of three genetically diverged Iranian populations o f DPH (Bam, Jiroft, and Tezerj) were determined on two date palm cultivars (Berhi and Kh unizi). The age-stage, two-sex life table theory was used to unveil biological differen ces among these populations. All experiments were carried out in a laboratory at 27± 2 ̊C, 65±5% RH, and a photoperiod of 14:10 (L: D) hour. The results revealed significant differences in life history traits and growth parameters of different populations. The sho rtest development time was observed in the Bam population (75.86 and 85.03 days on Berh i and Khunizi, respectively). The highest values of the intrinsic rate of increase ( r ) and finite rate of increase ( λ ) were detected in Bam population (0.0377 and 1.0433 per d ay on Berhi as well as 0.0284 and 1.0288 per day on Khunizi, respectively). Based on these results, we can consider Bam as an aggressive population with higher infestation ra te compared with the other populations due to its higher r and λ values as well as shorter mean generation time on both host cultivars. The significant differences in life history traits and variation in population growth parameters may suggest the presen ce of cryptic species among these populations. It can stem from the high genetic dive rgence among DPH populations which may be orchestrated by mismanagement of the pest. Keywords : Berhi date, Demographic parameters, Dubas bug, Kh unizi date, Insect population growth.