Bioinsecticidal potential of Vinca rosea against the tobacco caterpillar, Spodoptera litura Fabricius (Lepidoptera: Noctuidae)

The tobacco caterpillar Spodoptera litura Fabricius has emerged as a serious and dominant pest on many agricultural crops causing enormous losses. The use of plant extracts of various medicinal plants against the different developmental stages of S. litura  to test their efficacy in organic farming is the need of the day. A crude aqueous extract of leaves of Vinca rosea at different concentrations from 2 per cent to 40 per cent at an increment of 5 per cent was administered to lab-reared; pre starved fourth instar larvae topically as well as through food. The fourth instar larvae treated topically with the 25 per cent extract exhibited a total larval mortality of 91.66±1.66 per cent and the maximum total per cent mortality was 93.33±1.66 during its development to the adult stage. The larvae that were administered the plant extract through their food showed an 85.0±2.88 per cent total larval mortality and 93.0±1.66 per cent total mortality at 25 percent concentration. Deformities were observed in the dead larvae, pupae and adults. The LC 50 and LC 90 for topical application was 18.87 and 42.98 .The same for leaf application was 21.07 and 45.38. The botanical showed its continued bioinsecticidal effect in the F1 generation. There was a reduced hatchability of eggs (47.66 p±0.66 per cent compared to the 65.33±0.88 per cent in the absolute control, for topical application.) and also a significant per cent mortality of first instar larvae within two hours of hatching (53.36±0.66 per cent for topical application and 21.36±0.33 per cent for leaf application) crude aqueous leaf extract of Vinca rosea was found to be effective in the management of the polyphagous pest S  litura F