Life cycle and fecundity of Spodoptera exigua (Lep.: Noctuidae) on five soybean varieties

Effect of five soybean varieties (Sahar, JK, BP, Williams and L17) on life cycle and fecundity of the beet armyworm, Spodoptera exigua (Hübner) was evaluated at temperature of 25 ± 1°C, 60 ± 5% R.H. and a photoperiod of 16: 8 (L: D) h. The preimaginal development period of males and females was longest on L17 (30.17 ± 0.28 and 29.63 ± 0.23 days) and shortest on BP and Sahar. The adult longevity of males and females was longest on Williams (13.86 ± 1.14 and 20.20 ± 1.12 days) and shortest on Sahar (9.36 ± 0.59 and 12.75 ± 0.69 days), respectively. The life span was longest on L17 (44.86 ± 0.85 days) and shortest on Sahar (39.00 ± 0.50 days). The highest percentage of egg and larval mortality was observed on L17 (73.48 and 39.35%, respectively), but the highest percentage of pupal mortality was on Sahar (12.50%). The lowest percentage mortality of egg (57.96%) and larval (10.81%) stages was obtained on Williams. The pupal weight of females was heaviest on Sahar (88.10 ± 3.01 mg) and lightest on BP (73.00 ± 4.18 mg) compared to the other varieties. The highest number of eggs laid per female per day was 58.19 ± 4.53 on L17 and the lowest number of eggs was 37.91 ± 3.01 on BP. The results showed that total number of eggs laid per female was highest on Williams (569.50 ± 29.8 eggs) and lowest on Sahar (448.90 ± 19.5 eggs). Knowledge of the biology of S. exigua on soybean varieties can aid us to detect and monitor the pest infestation, variety selection and crop breeding.