Antifeedant and Growth Inhibitory Effects of Medicinal Plant Extracts against Tobacco Caterpillar, Spodopteralitura Fab.

摘要

The intensive and indiscriminate use of pesticides inagriculture has caused many problems to the environment such aswater, soil, animal, food contamination and elimination of non-targetorganisms. The plant extracts not only act as insecticides but alsofunction as antifeedants, oviposition deterrents and ovicides. Keepingin view the imperative demand of safer plant protects and aiming tominimize the negative effects of pesticides, present study isundertaken to study the impact of aqueous medicinal plant extractson growth and development parameters of 7 days old larvae ofSpodopteralitura. Among the twelve plants tested,Cinnamoumcamphora and Withaniasomnifera showed strongantifeedant activity with C-value of 0.41 and 0.42 respectively. Highfeeding deterrent property was exhibited by C. camphora withfeeding inhibition of 59.18 followed by W. somnifera 57.89% and alow level of deterrent activity was exhibited by E. cardamomum(4.53%) followed by B. orellana (7.23%). The significant impact wasobserved on pupal deformity with all the plant extracts. Maximumpupal deformity was observed with W. somnifera 10.37 and 10.73%followed by A. paniculata, 8.09and8.33% at 25and50 % concentrationrespectively. All the plant extracts at 50% concentration significantlyreduced the growth index, the values for the different plant specieswere; P. zeylanica (2.01), A. paniculata (2.06), B. monnieri (2.44),W. somnifera (2.51), R. serpentina (3.15) and C. camphora (3.35) incomparison to control (3.80). The extracts of W. somnifera and B.orellanapossess insecticidal and juvenomimetic properties against S.litura, as total growth and development were reduced, resulting indeformed individuals which will ultimately affect the futuregeneration of the test insect.