Infectivity of native populations of entomopathogenic nematodes against teak defoliators
Nitin Kulkarni, Vinod Kumar Mishra and Sanjay D Paunikar
The paper reports evaluation of hitherto unknown infectivity of six native populations of entomopathogenic nematodes (EPNs) (five of the genus Steinernema, and one genus Heterorhabditis), including a new-to-science species Steinernema dharanaii (TFRIEPN-57) against two important defoliators of teak (Tectona grandis); Eutectona machaeralis and Hyblaea puera. The study was carried out during the months, July to October all through 20012 to 2015, aiming to explore possibility of using these EPNs as foliar spray against the target pests as biological control. The penultimate instar larvae of both the defoliator species collected from teak plantation and forest areas in Madhya Pradesh and subsequently reared in laboratory for the purpose, were exposed to all six native populations of the EPN, Heterorhabditis spp. (TFRIEPN-50) and five populations of Steinernema spp. (TFRIEPN-56, TFRIEPN-49, TFRIEPN-23, TFRIEPN-57, TFRIEPN-15), in 10 doses ranging from 3 to 50 IJs larvae-1. Two known NBAII populations; Steinernema carpocapsae and Heterorhabditis indica were also used as standards for comparison of results. Results indicated population-specific and dose-dependent mortality (>80%) at and above 35 IJs L-1 by all populations except TFRIEPN-56. All EPNs caused infectivity at and above the dose of 10 IJs L-1. EPN, Heterorhabditis indica (TFRIEPN-50) and H. indica exhibited highest level of mortality (85.71%) 25 to 30 IJs L-1 and proved the best populations in terms of infectivity against the targeted pests.