Long-term effects of methoxyfenozide on the longevity and reproductive processes of beet armyworm, Spodoptera exigua (Lepidoptera: Noctuidae), adults

LUNA, JUAN CARLOS; ROBINSON, VIRGINIA ANGÉLICA; MARTINEZ, ANA MABEL; SCHNEIDER, MARCELA INÉS; FIGUEROA, JOSE ISAAC; SMAGGHE, GUY; VIÑUELA, ELISA; BUDIA, FLOR; PINEDA, SAMUEL

JOURNAL OF ECONOMIC ENTOMOLOGY

ENTOMOLOGICAL SOC AMER

Año: 2011 vol. 104 p. 1229 - 1235

0022-0493

The long-term effects of methoxyfenozide on the longevity and reproductive processes of beet armyworm, Spodoptera exigua Hübner (Lepidoptera: Noctuidae), adults were assessed following exposure by ingestion. Methoxyfenozide significantly reduced adult male longevity compared to females by 1.1 and 1.5 d at 75 and 150 mg AI/liter, respectively. The mean number of eggs laid per female decreased by more than 60% in both concentrations tested at 72 and at 96 h after treatment, but at 48 h, no significant effect was observed. The carbohydrate, protein, and lipid content in the eggs were determined as representatives of the biochemical effects of methoxyfenozide associated with the disruption of reproductive processes. The content of carbohydrates in the eggs laid 48 h after treatment was similar to that of controls, but it increased by ~1.5 and 2 fold in eggs laid after 72 and 96 h, respectively, compared to controls (15 µg/egg at both collection times). With respect to protein content, there was a reduction of ~2.5 and ~3 fold for each treatment concentration, respectively, compared to the controls (25 and 23 µg/egg for 75 and 150 mg AI/liter, respectively) in eggs collected 72 and 96 h after treatment began. Lipid content significantly decreased by ~1.6 fold in both treatment concentrations in eggs collected at 48 and 96 h after treatment compared to the controls (24 and 21 µg/egg for 48 and 96, respectively), but it was similar to controls (~19 µg/egg) at 72 h (~15 µg/egg) after the beginning of treatment for both concentrations. The biochemical effects of methoxyfenozide on S. exigua egg formation detected in this work are consistent with the reduction in fertility observed, as reported previously.