Cholinesterase in mosquito larvae: histochemical identification and localization in fourth instar Culiseta inornata (Williston) (Diptera: Culicidae)

The Goraori acetylthiocholine technique was used to investigate the distribution of cholinesterase in fourth instar larvae of Culiseta inornate (Nilliston). Fixed and especially prepared larvae were incubated in the substrate solution for the required time, the larvae were imbedded in paraffin, and serial sections were prepared. Microscopic examination of the material revealed a strong histochemical reaction throughout the central nervous system. Faint reactions, not apparent in many of the preparations, were sometimes found associated with muscle, gastric caecae, or Malpighian tubules. The use of selective enzyme inhibitors indicated that the cholinesterase in C. inomata larvae cannot be catagorized as either acetylcholinesterase or pseudo-cholinesterase.