Development and population growth of Stephanitis pyri (F.) (Heteroptera : Tingidae) at five temperatures

Abstract

Pear lace bug, Stephanitis pyri (F.) (Heteroptera: Tingidae) is a pest of apple and pear trees and ornamental Rosaceae plants in Mediterranean countries and palearctic region. The aim of this study is to determine the effects of temperatures on S. pyri in the laboratory. Development and fecundity of S. pyri reared on apple leaves (Pyrus malus L.) were investigated at five constant temperatures (20, 23, 26, 29 and 32 +/- 1 degrees C) and a 16L:8D photoperiod. Longevity was determined to be 12.6 days at 32 degrees C and 58.7 days at 20 degrees C for females, and 9.7 and 37.7 days for males. Females laid 186.9 eggs per female with the highest number achieved during 28.5 days of oviposition period at 26 degrees C. Female lifetime fecundity was reduced at 32 degrees C (40.0 eggs per female). While the net reproductive rate (R-0) was highest at 26 degrees C, the intrinsic rate of natural increase (r(m)) was highest at both 26 and 32 degrees C. The mean generation time (G) was estimated to be 27.2-78.4 days at 20 and 32 degrees C, respectively. The longest development times for egg and total nymph stages were obtained as 22.0 and 24.9 days, respectively, at 20 degrees C. S. pyri developed fastest from egg to egg in 24.3 days at 32 degrees C. The lower developmental threshold (T-0) was 9.7 degrees C and the thermal constant (K) was 517.3 degree-days for S. pyri. Thus, S. pyri is calculated to have 3.8 theoretical generations in Tekirdag. The optimum developmental temperature for S. pyri was 26 degrees C.