Population growth of pear bedstraw aphid, Dysaphis pyri, on different pear cultivars

Population growth parameters of pear bedstraw aphid, Dysaphis pyri, were evaluated on four different pear cultivars (Coscia, Williams, Santa-Maria, and Quins.a/Ankara) under field conditions in the Van region of Turkey. Experiments were carried out on exterior leaves of trees 1.5-2 m above the ground. Plexiglas clip-cells (20 mm in diameter and 10 mm in height, with the upper side covered with muslin) were used in this study.  Developmental time, survival and fecundity data were analyzed using the age-stage, two-sex life table to take the variable developmental rate among individuals into consideration. Results indicated that Coscia and Quins.a/Ankara are less favorable hosts for bedstraw aphid because of the longer preadult developmental time, higher preadult mortality rate, and lower total fecundity on these cultivars.  The intrinsic rate of increase (r), the net reproduction rate (R₀) and the finite rate of increase (λ) values were lower on Coscia and Quins.a/Ankara.