A comparison of tricarboxylic acid cycle intermediates in the haemolymph of healthy Culex pipiens, Aedes taeniorhynchus and Anopheles quadrimaculatus larvae and larvae parasitised by the mermithid Romanomermis culicivorax

Abstract

Tricarboxylic acid cycle intermediates in the haemolymph of healthy and infected larvae of Culex pipiens, Aedes taeniorhynchus and Anopheles quadrimaculatus were determined by enzymatic analyses and gas-chromatographic procedures. Pyruvate increased by over 100% in C. pipiens late fourth stage healthy larvae compared with early fourth stage larvae and α-ketoglutarate contents were reduced in the late fourth stage larvae of all three species. Malate was the predominant haemolymph acid with appreciable amounts of citrate and lactate. Haemolymph from larvae infected with Romanomermis culicivorax, compared with that from healthy larvae of C. pipiens and A. taeniorhynchus showed no change in succinate, but fumarate, malate and citrate concentrations were higher. Lactate and α-ketoglutarate concentrations were elevated in A. taeniorhynchus but remained unchanged in the other two species. Oxaloacetate was reduced to undetectable levels in C. pipiens and A. taeniorhynchus infected larvae. Lactate, succinate, malate, oxaloacetate and fumarate remained unchanged between healthy and infected A. quadrimaculatus larvae, but citrate and pyruvate were reduced. Pyruvate concentration was also reduced in C. pipiens infected larvae, but remained constant in A. taeniorhynchus.