Influence of the gregarine Stenophora julipusilli (Eugregarinorida, Stenophoridae) on the trophic activity of Rossiulus kessleri (Diplopoda, Julidae)

Abstract

Analysis of the contents of the intestines of Rossiulus kessleri (Lohmander, 1927) revealed presence of gamonts of Stenophora daulphinia Watson, 1916, S. juli (Frantzius, 1846) Labbe, 1899 and S. julipusilli (Leidy, 1853) Crawley, 1903. For the analysis of the consumption of leaves of Acer negundo L. in the course of a two week laboratory experiment 122 specimens of R. kessleri infested with S. julipusilli, and 32 specimens not infested with gregarines were investigated. The initial and final body weight of each millipede was determined as well as the mass of food consumed, the amount of excrement produced and the extent of infestation with gamonts of S. julipusilli. No relationship between the amount of food consumed and initial weight of R. kessleri specimens was found. Nor was any dependence between the amount of excrement, amount of food consumed and change in body mass established. S. julipusilli gamonts and syzygys were found in 79.2% of millipede specimens. The infestation with gamonts of younger R. kessleri specimens was significantly lower than with average to large specimens of millipedes. The sex of the host was not found to influence food consumption, change in body mass or in mass of faeces. The extent of infestation with gamonts of S. julipusilli did not significantly differ between males and females of R. kessleri. In specimens not infested with gregarine gamonts the food consumption during the two-week experiment was at a high level, in those with a slight infestation (1–8 gamonts) it increased by 29%, in those with average and high extent of infestation it decreased by 8% compared with uninfested individuals. During the experiment influence of the number of S. julipusilli gamonts upon change in body mass and production of excrement by R. kessleri was not observed.