Effect of Exposure Time on EPN's Progeny Production and Mortality of Spodoptera litura Fabricius (Lepidoptera: Noctuidae) and Galleria mellonella (L.) (Lepidoptera: Noctuidae) Shakeela V.1,*, Hussaini S.S.2 1Bio-control Research Laboratories, Pest Control India Pvt. Ltd., Bangalore, Karnataka, India 2Ex National Bureau of Agriculturally Important Insects, Bangalore, Karnataka, India *Corresponding author; E-mail: shakeela.v@gmail.com
Online published on 26 December, 2016. Abstract Effect of exposure time on nematode induced mortality of larvae of Spodoptera litura and Galleria mellonella was significant. Larval mortality increased as exposure to nematodes increased. Species effects were observed in larval mortality and progeny production during shorter time periods. In general, it was observed that Heterorhabditis spp. required longer exposure period than Steinernema spp. to bring in comparable mortality. S. feltiae and S. abbasi were found highly virulent causing absolute mortality of insects at shorter exposure periods 1 and 3 h., while S. carpocapsae PDBC EN 11 caused absolute mortality of larvae in 3, 6 and 9 h exposure. Larvae of S. litura exposed to S. feltiae for 3h and to S. abbasi and S. carpocapsae for 6h and to heterorhabditids for 9h suffered 100% mortality. In case of G. mellonella, 1h. exposure to S. feltiae and S. abbasi, 3h to S. carpocapsae and 6h to heterorhabditids caused absolute mortality. It was observed that a period of 3h of exposure was sufficient for steinernematids to cause infection above 60%. However, the minimum exposure period of 6h was required in case of H. indica and H. bacteriophora to achieve significant mortality. The progeny production of nematode species also showed significant variation with respect to time exposed. Progeny production of nematode species was maximum in insect larvae exposed for 6 and 9h. So the exposure with nematodes for at least 6h is necessary to induce significant mortality as well as nematode multiplication in target insects. Top Keywords Entomopathogenic nematode, Steinernema, Heterorhabditis, Exposure time assay, Spodoptera litura, Galleria mellonella. Top |