Mollashahi M., Sahragard A., Mohaghegh J., Hosseini R., Sabouri H. (2016): Effect of two host plants, Helianthus annuus L. and Sinapis arvensis L., on life table parameters of Nysius cymoides (Spinola) (Hemiptera: Lygaeidae) under laboratory conditions. Plant Protect. Sci., 52: 209-216.The false chinch bug, Nysius cymoides (Spinola) is a pest of sunflower attacking sunflower fields from their weedy and cultivated hosts. The effect of sunflower and wild mustard (wild host) on the life table parameters of N. cymoides was studied under laboratory conditions (24 ± 1°C, 65 ± 5% RH, a 16 : 8 h (L : D) photoperiod). Data were analysed based on the age-stage, two-sex life table theory. Developmental time (sum of incubation and nymphal periods) on wild mustard was longer than on sunflower with significant difference (P < 0.05). The adult longevity was significantly shorter on wild mustard than on sunflower. The adult pre-oviposition period (APOP), total pre-oviposition period (TPOP), mean fecundity and adult longevity reared on sunflower and wild mustard showed significant differences (P < 0.05). The highest fecundity (58.72 eggs) and the longest female longevity (68.09 days) were on sunflower and lowest fecundity (5.67 eggs) was on wild mustard. The intrinsic rate of increase (r) on sunflower was higher than that on wild mustard, as it was 0.0437 ± 0.0039 on sunflower and 0.00033 ± 0.00599 per day on wild mustard and net reproductive rate (r 0 ) on sunflower and wild mustard was 12.94 ± 2.77 and 1.075 ± 0.34 (offspring), respectively. The mean generation time (T) was 58.01 ± 1.59 and 56.76 ± 2.43 days, on sunflower and wild mustard, respectively. The life expectancy (e xj ), survival rate (s xj ), and cumulative reproductive rate (r x ) on sunflower were higher than wild mustard. The results showed that sunflower was more suitable host than wild mustard to N. cymoides.