| Abstrakt: |
Background: Entomopathogenic nematodes (EPNs) are one of the widely studied biological control agents. The present study was conducted to evaluate the efficacy of two EPNs species, Heterorhabditis bacteriophora(Poinar) (Rhabditida: Heterorhabditidae) and Steinernema aciari(Qui, Yan, Zhou, Nguyen and Pang) (Rhabditida: Steinernematidae), isolated locally from soils of Majuli river island, Assam, India against two important subterrenean pests; Odontotermes obesus(Rambur) (Isoptera: Termitidae) and Agrotis ipsilon(Hufnagel) (Lepidoptera: Noctuidae) under laboratory conditions. Results: In case of O. obesus,mortality percent was recorded by H. bacteriophoraafter 72 h. at 300 IJs/termite and by S. aciariat 250 and 300 IJs/termite after 96 h. The lowest LD50and LT50values obtained for H. bacteriophorawere 13.054 IJs/termite and 26.639 h., respectively, while those of S. aciariwere 42.040 IJs/termite and 31.761 h., respectively. With respect to A. ipsilon, H. bacteriophoraregistered a highest mortality rate at 300 IJs/larvae after 144 h. S. aciarishowed 100 percent mortality at 300 IJs/larva after 168 h. The lowest values of LD50and LT50for H. bacteriophorawere 35.711 IJs/larva and 83.050 h., respectively. The lowest values of LD50and LT50for S. aciariwere 71.192 IJs/larvae and 97.921 h., respectively. Overall, H. bacteriophoradisplayed more virulence toward O. obesusand A. ipsilonthan S. aciari. Conclusion: Both native EPNs were found effective against O. obesusand A. ipsilon.However, H. bacteriophorawas more virulent toward O. obesusand A. ipsilonthan S. aciariunder the laboratory conditions. |
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