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

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Abstract

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.

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