Effects of the mermithid nematode Mermis nigrescens on the levels of hemolymph and fecal uric acid in its host, the migratory locst Locusta migratoria

In further investigations on the effects of parasitism by Mermis nigrescens on locusts [see RAE/A 61, 4050; 63, 1919], second- and third-instar nymphs of Locusta migratoria (L.) were infected with ova of the mermithid. After 24 days (when parasitic development had been completed), the haemolymph of parasitised locusts contained over 5 times the concentration of uric acid as that of unparasitised ones, while the concentration of faecal uric acid was reduced to one-quarter. These results are discussed in relation to the host-parasite relationship.ADDITIONAL ABSTRACT:The haemolymph of Locusta migratoria 24 days after infection with 80 Mermis nigrescens ova contained over 5 times the concentration of uric acid than that of uninfected controls. The concentration of faecal uric acid was reduced by infection to a quarter of that in controls. At the end of the experiment the locusts harboured an average of about 20 4th-stage larvae in their haemocoel..