Survey on the prevalence of jasmine leaf web worm, Nausinoe geometralis and its natural enemies in Tamil Nadu
I Merlin Kamala and JS Kennedy
Jasmine leaf webworm (Nausinoe geometralis) was found to be the serious pest of jasmine posing severe threat to the plant. Roving surveys were conducted in 2014-15 in the major jasmine growing districts of Tamil Nadu, to study the incidence of jasmine leaf webworm and the natural enemies associated with it in managing the pest naturally. Field surveys indicated the presence of the pest incidence in the entire surveyed region in varying intensity with maximum incidence recorded in Madurai (28.75%) and Coimbatore districts (27.65 %) respectively. Cocinellid predators like Cheilomenes sexmaculata, Cocinella transversalis, Scymnus sp., Coccinella septumpunctata, Brumus suturalis, Illeis cincta and Chilocorus sp. were present in the jasmine ecosystem with a mean population of 3.04 cocimellids per plant. Neuropteran predators, Chrysoperla zastrowi sillemi andMallada boninensis were found effectively managing the egg and early instars of leaf webworm with a mean population of 2.2 per plant. A wide range of preying mantises and spiders with a mean population of 3.8 and 4.3 per cent respectively was present. Larval parasitoids like Bracon sp., Elasmus sp., and Apanteles sp., played a vital role in natural suppression of the pest. Native weeds and flowering plants like Parthenium hysterophorus, Rosa sp., Nerium oleander, Vernonia cinera, Datura metal, Lantana camara, Tagetus erceta, Ipomea carnea, Helianthus annus and Coriander sativumwere found to provide nectar to the adult stages of the parasitoid. The mean parasitism of the leaf webworm larva by these parasitoids was 1.74 per cent.