Biology and demography of the dubas bug, Ommatissus lybicus (Hem.: Tropiduchidae), at three constant temperatures

Biology and demography of Ommatissus lybicus de Bergevin was studied under controlled conditions at 25 ± 1, 30 ± 1 and 35 ± 1˚C and 60 ± 5% RH and 16: 8 L: D. Forty eggs of the pest (0-24 h old) were used in each temperature treatment. Developmental time was obtained 82.48 ± 0.72, 75.79 ± 0.55 and 89.85 ± 0.71 days at 25, 30 and 35˚C, respectively. Moreover, at 35˚C, most of the biological activities of the dubas bug were disrupted and individuals, especially females, incurred relatively high mortalities. Female life span was significantly higher at 25˚C (108.21 ± 1.33 days) comparing to that of the other temperatures. The net reproductive rate (R0) was 45.93 and 52.31 at 25 and 30˚C; however, it extremely decreased at 35˚C (5.82). The intrinsic rate of increase (rm) was 0.054, 0.062 and 0.029 at 25, 30 and 35˚C, respectively. Similarly, doubling time (DT) was also close at 25 and 30˚C (14.2 vs 12.3 days) but it increased dramatically at 35˚C (29.27 days). Based on life table parameters observed, it was concluded that 30˚C could be an optimum temperature for the biological activities of O. lybicus.