Effects of Plagiorchis elegans (Trematoda : Plagiorchiidae) infection on the carbohydrate metabolism of fourth instar Aedes aegypti (Diptera : Culicidae)

Infection of fourth-instar Aedes aegypti (L.) with the entomopathogenic dig enean Plagiorchis elegans (Rudolphi) alters the carbohydrate metabolism of the insect. Within 24 h of cercarial penetration, total body extracts of in fected fourth instars exhibited decreased trehalase activity, increased tre halose-6-phosphatase activity, and a concomitant accumulation of trehalose when compared with uninfected larvae. The amounts of glucose, glycogen and lipids, and the activity of glycogen phosphorylase a were similar in extrac ts of infected and control larvae. The predominant fatty acids, in both con trol and infected larvae, were C 18:0, C 18:1, and C 18:3. There were no si gnificant differences in the types or proportions of fatty acids found in c ontrol and infected larvae. Parasitic infection is discussed in terms of im paired trehalose metabolism.