Effect of temperature on the survival and infectivity of new species of entomopathogenic nematode, Steinernema dharanaii (TFRIEPN-15) from Madhya Pradesh, central India
Sanjay Paunikar, Nitin Kulkarni
The effect of different temperatures ranges on the survival and infectivity of indigenous isolated entomopathogenic nematode, Steinernema dharanaii (TFRIEPN-15) was studied in the laboratory. The temperature ranges 00C to 400C were exposed to IJs for different time period. The exposed IJs was also assessed the infectivity in different temperature. The result indicated that exposure TFRIEPN-15 IJs to 10 to 340C for 72 hrs IJs did not show any marked effect, but temperature below 100C and above 340C exhibited significant mortality. The Infective Juveniles (IJs) of TFRIEPN-15, when exposed to 00C and 380C, could tolerate only up to 12 hrs, above which exposure time no survival was observed. The exposure to extreme temperature of 400C, allowed only 31.20 and 8.80% survival respectively at exposure period of 15 and 30 min., with finally 100.0% mortality after 60 min. of exposure. The infectivity of IJs pre-exposed to extreme temperature to waxmoth larvae was proportional to the exposure period. The period of exposure of IJs to 00C above 8 hrs affected infectivity potential of the pre-exposed IJs. IJs exposed for 2 hours were able to infect 100.0% Galleria mellonella larvae. Thereafter, the percentage of infectivity decreased. The IJs exposed for 4 and 6 hrs infected 80.0% and 32.0%, Further exposure to 8 hrs proved detrimental to the infectivity potential with only 16.0% infectivity to waxmoth larvae. Therefore, while temperature of 27±0C (control) proved optimum for mass-economical mass-multiplication purpose. However, this native population could sustain temperature range of 10 to 340C for 72 hrs, 0 and 380C for 12 hrs, which is a sufficient time for exploiting it as biological control agent, if planned judiciously.