Amino acids and phosphates stimulate hatching of Ochlerotatus koreicoides (Diptera : Culicidae) eggs

A tree-hole mosquito species, Ochlerotatus (Finlaya) koreicoides has been reared in laboratory by stimulating their hatch using dried yeast powder. This method shows to be more effective than lowering the dissolved oxygen concentration by mechanical, chemical or biological means. From a hatch test guided fractionation of the water extract of dried yeast, glutamic acid was isolated as the main compound of the hatch stimulating fraction. This amino acid alone did not show hatch stimulating effect but it was effective in combination with the phosphates that are also constituents of dried yeast. Among 20 amino acids, only histidine and proline showed similar effects as glutamic acid. A concentration of 0.1mg/ml of each glutamic acid and trisodium phosphate gave high percentage hatch in 18 h.