Larvicidal efficacy of Verbascum spp. methanol extracts against Plodia interpunctella (Hübner, 1813) (Lepidoptera: Pyralidae)

Abstract

Verbascum species (fam. Scrophulariaceae) contain a high concentration of rotenone and verbascoside and traditionally have long been used as insecticides. This study is aimed to investigate the larvicidal efficacy of Verbascum thapsus L. and V. phlomoides L. methanolic extracts in the suppression of the Plodia interpunctella (Hübner, 1813), under laboratory conditions. The experiment was set up in two separate blocks (for two different extracts), each as 3˟3˟3 factorial trial: three concentrations of extracts (1, 2 and 5%) were tested against the three larval age groups (14, 14-28 and 28 days old) and each treatment was repeated three times. Mortality was recorded after 24, 48, 72, and 96 h. Both tested extracts were the most effective 96 h after the exposure in 5% concentration applied on the youngest larvae. Extract of V. thapsus caused the mortality of 64.00%, while in treatment with V. phlomoides extract mortality was 48.00%. Tested Verbascum extracts have shown moderate potential for application as botanical larvicides.