Effects of mermithid nematode parasitism on the hemolymph composition of blackflies.

This paper (only an abstract of which is given) was presented at the Sixteenth Annual Meeting of the Society of Nematologists held at East Lansing, Michigan, from 16 to 19 August 1977. An account is given of studies carried out in Canada on the effect of parasitism by the mermithid nematode Neomesomermis flumenalis on the haemolymph composition of last-instar larvae of Simulium venustum Say, which develops in summer, and either Prosimulium mixtum Syme & Davies or P. fuscum Syme & Davies (not determined by the authors), which develop in winter. Parasitised insects usually harboured one nematode. Polyacrylamide-disc electrophoresis showed that parasitism generally caused a non-selective depletion of protein fractions in both hosts. The levels of most amino compounds were reduced by parasitism in Prosimulium, but the effect varied with the compound in Simulium. Phosphoethanolamine, methionine sulfoxide, citrulline, tyrosine and histidine were severely depleted in the blood of both hosts. The depletive effect of the parasite on blood proteins resulted from utilisation by the nematode of host amino acids and caused severe exhaustion of the latter compounds in Prosimulium blood. Pronounced increases in the levels of many blood amino compounds in Simulium may have resulted from differences in nutrition, the primary structure of proteins, or rates of protein catabolism between the 2 parasitised host species. The effects of parasitism on haemolymph carbohydrate levels of the hosts were noted.ADDITIONAL ABSTRACT:This paper (only an abstract of which is given) was presented at the Sixteenth Annual Meeting of the Society of Nematologists held at East Lansing, Michigan, from 16 to 19 August 1977. An account is given of studies carried out in Canada on the effect of parasitism by the mermithid nematode Neomesomermis flumenalis on the haemolymph composition of last-instar larvae of Simulium venustum Say, which develops in summer, and either Prosimulium mixtum Syme & Davies or P. fuscum Syme & Davies (not determined by the authors), which develop in winter. Parasitised insects usually harboured one nematode. Polyacrylamide-disc electrophoresis showed that parasitism generally caused a non-selective depletion of protein fractions in both hosts. The levels of most amino compounds were reduced by parasitism in Prosimulium, but the effect varied with the compound in Simulium. Phosphoethanolamine, methionine sulfoxide, citrulline, tyrosine and histidine were severely depleted in the blood of both hosts. The depletive effect of the parasite on blood proteins resulted from utilisation by the nematode of host amino acids and caused severe exhaustion of the latter compounds in Prosimulium blood. Pronounced increases in the levels of many blood amino compounds in Simulium may have resulted from differences in nutrition, the primary structure of proteins, or rates of protein catabolism between the 2 parasitised host species. The effects of parasitism on haemolymph carbohydrate levels of the hosts were noted.ADDITIONAL ABSTRACT:Neomesomermis flumenalis parasitism of Prosimulium mixtum/fuscum and Simulium venustum in most cases caused a non-selective depletion of all protein fractions in both hosts, reduced blood amino acid concentrations in P. mixtum/fuscum and depleted levels of phosphoethanolamine, methionine sulphoxide, citrulline, tyrosine and histidine..