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|Title:||Bio-efficacy of different entomopathogenic nematode species against Scarab Grubs|
|Authors:||Rathour, K S|
|Abstract:||Entomopathogenic Nematodes (EPNs) of the families Steinernematidae and Heterorhabditidae are being used as potential biological control agents against several insect-pests of turf grass, citrus, vegetables, fruits and other agriculturally important crops, as well as many veterinary and house-hold insect pests including termites. They carry symbiotic bacteria <i>Xenorhabdus </i>spp. (Steinernematidae) and <i>Photorhabdus </i>spp.(Heterorhabditidae) which is required to kill the insect host and to digest its tissues, thereby providing nutrient conditions for nematode growth and development. These nematodes kill the host insect within 24-48 h. by causing septicemia, complete their life cycle inside the cadavers and emerge <i>en-masses </i>within 4-5 days after mortality in case of steinernematidae and 9-15 days in case of helerorhabditids. Scarabs (Order Coleoptera) are serious pests of several field crops. Their adults feed on foliage while their larval forms, commonly called as white grubs, live in soil and feed on roots. Our recent surveys showed heavy population of grubs in the rhizosphere of sugarcane in Meerut. The grubs were collected from the fields for use in the present study. Managing scarab grubs by entomopathogenic nematodes is highly challenging because they tend to avoid infection by frequent defecation. The biocontrol efficacy of 8 EPN species/strains viz. <i>Steinernema thermophilum; S. glaseri; S. riobrave </i>strain GAU-M; S. <i>carpocapsae </i>strain Megha-1; <i>Heterorhabditidae</i> <i>bacteriophora </i>strain GAU; indica strain Megha-3; <i>Heterorhabditiditis </i>strain Haryana-2 and Haryana-5 was tested against scarab (<i>Hototrichia cosanguina</i>) larvae. All the species/strain were found to be highly efficacious against scarab larvae and could induce 80-100% mortality with in 5-6 DAI (days after inoculation). Among the tested species/strain <i>S. glaseri </i>was found to be highly efficacious inducing 100% mortality within 5 DAI; followed by <i>S.</i> <i>thermophilum, </i>and <i>H. indica </i>causing 100% mortality within 6 DAI. The other tested species/strain <i>S. riobrave, S.</i> <i>carpocapsae, Heterorhabditis </i>strain Haryana-2. <i>H. bacteriophora </i>and <i>Heterorhabditis </i>strain Haryana-4 could induce only 80% mortality up to 6 DAI. The higher efficacty of <i>S. glaseri </i>is attributed to its cruising type behavior best suited for accessing scarab larvae. In view of the pesticide resistance being developed in several insects, EPNs can be a suitable eco-friendly option for incorporating in integrated pest management programmes.|
|ISSN:||0975-2412 (Online); 0771-7706 (Print)|
|Appears in Collections:||BVAAP Vol.18(1) [June 2010]|
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