Studies on ascaridoid nematodes in pythons: the life history and development of Polydelphis anoura in Australian pythons

Abstract

SUMMARYP. anoura was found in 55 % of pythons (M. spilotes variegatus) in Brisbane. Eggs contained first stage larvae after 8 days development; the first moult was completed by 10 days; the eggs were infective after 14 days. After ingestion by tadpoles, the larvae hatched from the eggs and migrated into the tissues but did not show any growth. In mice and rats the larvae migrated mainly to the liver, lungs and intestinal wall, where growth occurred to a length of 5–6 mm by 6 months after infection. The second moult was not observed, but the larvae were infective to pythons after 39–42 days development. From their structure it was assumed that after this time the larvae in mouse tissues were third-stage larvae.Various species of Australian python, Morelia spilotes, Liasis amethistinus, L. fuscus and L. childreni, were experimentally infected with larvae of Polydelphis anoura by feeding nodules from the wall of the small intestine of experimentally infected mice and rats. The third moult occurred in the stomach within 14 days, moulting larvae at this stage measured between 3.5 and 7.0 mm long. Fourth-stage larvae occurred in all python species, the smallest being 4 mm. Growth and development of the fourth stage occurred at first in the oesophagus and stomach. Up to 2 months after infection, larvae had not grown more than 12 mm, yet they were clearly differentiated into males and females. In mouse-infected M. spilotes growth to 20 mm was reached by 154 days, but it was not until 183 days that adults were observed.Comparison with adult specimens from P. reticulatus from Malaya confirmed the previous observation that Australian male specimens have relatively shorter spicules than male specimens from other geographical regions. Growth, development and location of larvae in mice, experimentally infected with eggs from Australian and Malayan specimens, appeared to be the same.