Biotic potential and reproductive parameters of Spodoptera ornithogalli (Guenée, 1852) (Lepidoptera: Noctuidae) in the laboratory

Abstract

The yellowstriped armyworm, Spodoptera ornithogalli (Guenée, 1852) (Lepidoptera: Noctuidae), is distributed throughout the Americas, with the exception of Chile. Its polyphagous larvae are significant pests, damaging major annual crops, vegetables, ornamentals, and plant nurserie. This study evaluates the biotic potential and reproductive parameters of this species under controlled conditions (25 ± 1 °C, 70 ± 10% RH, and a 14-h photophase). Two experimental sets were conducted. The first (Set 1), was designed to allow comparisons with data from other species studied under similar conditions, and assessed reproductive parameters using one couple per cage. The second (Set 2), evaluated reproductive parameters using groups consisting of one female and five males per cage. Overall, maintening one female with five males significantly altered reproductive parameters. Female longevity, the durations of the pre-oviposition and oviposition periods, were significantly reduced, whereas the number of matings and observed fecundity were significantly increased. The estimated biotic potential of S. ornithogalli was 1.724 × 10 32 individuals/female/year under the one-pair-per-cage condition, increasing to 6.555 × 10 33 individuals/female/year when females were kept with five males. Similarly, reproductive parameters such as the net reproductive rate ( R ₀ ), intrinsic rate of increase ( r ₘ ), and finite rate of increase ( λ ) were higher in the group with one female and five males, while the mean generation time ( T ) was shorter compared to the one-pair-per-cage condition. Compared to other agriculturally significant noctuid pests, S. ornithogalli exhibits a higher biotic potential, suggesting a greater capacity for rapid population grow.

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