The life table of the lucerne beetle, Gonioctena fornicata (Brüggem) (=Phytodecta fornicatus Brüggem) (Coleoptera, Chrysomelidae) on alfalfa under laboratory conditions

Abstract

In this study, the life table of Gonioctena fornicata (Brügg.) was constructed at 25±1 °C constant temperature, 60±5% relative humidity and 16:8 light:dark period in a climate cabinet. Life table parameters were calculated using the Euler-Lotka iteration method and their values were: Intrinsic rate of increase (rm), 0.015; Net reproductive rate (Ro), 180.25 females/female; Mean generation time (To), 353.03 days; Gross reproductive rate (GRR), 287.93 females/female; Doubling time, (T2) 47.11 days and Finite rate of increase (λ), 1.02 females/female. The fecundity rate was fitted in the Enkegaard equation and parameters were calculated as a = 0.886±0.055 ; b = 0.052±0.002. Mean development times for both sexes were: egg, 5.07, 2.85 days; larvae1, 2.83, 2.72 days; larvae2, 2.10, 2.36 days; larvae3, 2.15, 2.29 days; larvae4, 4.46, 4.29 days; pupae, 7.92, 7.69 days; total development time, 24.40, 24.32 days for females and males, respectively. Additionally, preoviposition, oviposition, postoviposition and generation times were 305.53, 32.73, 30.07 and 331.60 days, respectively. Life span of females was 366.07 days and it was 371.7 days for males. The best survivership curve was fitted to the Weibull distribution; its shape was defined as a Type I survivorship pattern and the calculated parameters were: b = 382.14±0.429 and c = 11.34±0.231.