Studies on in vitro Growth Rate of Culturable Gut Bacterial Flora of Three Stem Borers Infesting Rice (Oryza sativa)

Stem borers are the most devastating pest of rice globally. The present experiment was conducted to compare the in vitro growth rate under different temperature conditions of culturable gut bacteria isolated from three different rice stem borers viz., Scirpophaga incertulas (YSB), Chilo suppresalis (SSB) and Sesamia inferens (PSB). Growth was recorded spectrophotometrically by measuring optical density at 660 nm. The gut bacterial consortia of YSB and PSB grew better than those of SSB at lower temperatures (15 and 20 °C) while that of PSB performed equally well in the entire range of temperatures. The gut bacterial consortium of SSB grew luxuriantly with the increase in temperature with the peak growth at 30 °C. There was no marked difference in the growth trend of all the bacterial isolates at 30 °C. These results indicate differential temperature preferendum of gut flora and give insights into their possible relation with behavioural response of the host insect species at different temperature.