Is gut <i>p</i>H regulated by midgut endocrine system in larvae of <i>Rhynchophorus ferrugineus </i>Fab.?

Abstract

Midgut of the larvae of <i>R. ferrugineus </i>can be divided into anterior saccular midgut, anterior tubular midgut, posterior saccular midgut and posterior tubular midgut. <i>p</i>H of the contents in the anterior saccular midgut was 5-5.4. Effect of extracts of midgut epithelium on maintenance of gut <i>p</i>H in the final instar larvae has been studied employing an <i>in vitro </i>method. For this, ligated tubes of the anterior saccular midgut filled with <i>p</i>H indicator - buffer solutions having <i>p</i>H either 4 or 7 were incubated with midgut epithelial extract in a bioassay apparatus at 37°C. <i>p</i>H of the contents of midgut preparations changed to normal

range following incubation with epithelial extract as indicated by turning of colours. No change in colour was observed in controls incubated with insect saline for 60 min. The effect is both dose and time dependent. The midgut epithelial factor regulating <i>p</i>H in gut lumen could be a hormone.