Effects of Plant Extract Formulation, Kingbo on Larval Mortality, Food Consumption and Utilization, and Digestive Enzyme Activity of Agrotis Ipsilon
摘要
Agrotis ipsilon is a serious and polyphagous pest. The insecticidal activity of plant extract formulation, Kingbo on A. ipsilon larvae has not been reported before. Here, the toxicity of Kingbo, and its latent effects on food consumption and utilization and enzyme activity of larvae were tested. Our results demonstrated that Kingbo showed pronounced toxicity against A. ipsilon. Kingbo caused complete larval mortality (100%) at 0.5 ppm after 7 days and at 1 ppm after 5 days with higher toxicity levels (LC50 = 0.08, 0.02 and 0.014 ppm) after 3, 5 and 7 days of treatment, respectively. A concentration of 0.1 ppm was sufficient to induce full inhibition of pupation and adult emergence. Also, CI, GR and RMR of the fourth and fifth larval instars of A. ipsilon decreased with increasing Kingbo concentration levels. The CI, GR and RMR values of the fourth larval instar decreased to 176.0 ± 3.02, 15.0 ± 0.22 and 14.56 ± 1.32 at a concentration of 0.1 ppm, compared to 371.0 ± 3.73, 202.0 ± 7.87 and 74.55 ± 2.16 for the untreated larvae, respectively. The AD, ECI and ECD of the fourth larval instar decreased to 83.25, 4.18 and 4.33% at a concentration of 0.1 ppm, compared to 96.69, 56.16 and 67.96% for the untreated larvae, respectively. Exposure to Kingbo suppressed the digestive enzyme activities of proteases, lipase and amylase in treated larvae of A. ipsilon. These findings indicate that plant extract formulation, Kingbo was found to be a very effective toxicant and should be incorporated into A. ipsilon IPM strategies.