Management of root grub [Holotrichia longipennis (Blanch)] infesting Ginger (Zingiber officinale Rosc.) through entomopathogenic nematodes

Studies on the infectivity of EPNs Steinernema abbasi, S. carpocapsae and Heterorhabditis indica against root grub (Holotrichia longipennis) and the suitability of this insect for multiplication of infective juveniles of EPNs at different temperatures viz., 20, 25, 30 and 35°C was also tested. The results indicated that all tested EPNs were pathogenic to root grub. Although, per cent mortality and multiplication of IJs varied from species to species. % mortality of root grub and multiplication of infective juveniles of test EPNs were influenced by temperatures. Among the tested EPNs, H. indica and S. abbasi caused 100% mortality to root grub. However, S. carpocapsae killed 83% root grub after 72 hrs. Among the tested EPNs, H. indica yielded maximum number of infective juveniles followed by S. abbasi, whereas the lesser number of S. carpocapsae juveniles multiplied on root grub. At all temperatures studied, H. indica showed highest virulence, whereas S. carpocapsae the lowest one. Among the test temperatures, maximum mortality of insect was found at 30°C followed by 25°C, whereas the least mortality of root grub was recorded at 20 and 35°C. Maximum number of IJs was obtained at 30°C followed by 25°C, however, no multiplication of EPNs was recorded at 20°C, except multiplication of H. indica. In the present study, H. indica was found promising against root grub. The infectivity of the tested EPNs against root grub is opens up a new hope of utilizing them in insect pest management in ginger.