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We studied host damselflies Enallagma boreale (Odonata: Coenagrionidae) and their gregarine parasites (Apicomplexa: Eugregarinidae) to elucidate the causes and consequences of any sex biases in parasitism of adult hosts. Larvae of both sexes were highly infected, but there was no difference between male and female larvae in either prevalence or intensity of gregarine infections. Newly emerged adults had few or no parasites, thereby setting the stage for investigating accumulation of parasites by adults. Adult females had a higher prevalence and intensity of infection by gregarines than did males, but only on 1 (of 2) days when the potential confounding factor of host age was controlled for. Both adult males and females showed a positive correlation between longevity under conditions of food stress and the number of gregarines they initially carried. This finding may be explained if the food ingested with the infective cysts is more beneficial than the parasites are harmful, and it also has implications for investigating sex biases in numbers of trophically transmitted parasites of such insects.

We studied parasitism by gut protozoans (Apicomplexa: Eugregarinidae) in the damselfly, Nehalennia irene (Hagen) (Odonata: Coenagrionidae). We tested whether there was any seasonal pattern, as has been found for other parasites of damselflies and which has implications for selection on emergence and breeding. Using aggregate data from 12 date-by-site comparisons involving five sites, we found that both prevalence and intensity of gregarine parasitism were seasonally unimodal. Parasitism first increased and then declined seasonally after peaking mid-season. This damselfly species has shown seasonal increases in density followed by declines at several sites including a site sampled in this study. Therefore, similar seasonal changes in a directly transmitted parasite were expected and are now confirmed. Other factors that might account for seasonal changes in parasitism by gregarines are either unlikely or can be discounted including sampling of older damselflies mid-season but not late in the season, or sex biases in parasitism and overrepresentation of the more parasitized sex mid-season.

96 SummaryThe distribution of species of the Xiphinema americanumgroup in Hungary was studied by collecting 272 samples from 53 localities. Samples have been taken from soil in the rhizosphere of 70 plant species. In total, 12.86 % of the samples contained at least one species from the Xiphinema americanum-group. Three species were found: Xiphinema brevicollum, X. pachtaicum and X. simile. Xiphinema brevicollum occurred in 4.41 %, X. pachtaicum in 3.67 % and X. simile in 4.77 % of the samples. New data on plants associated with the reported species and developmental patterns for X. brevicollum and X. pachtaicum are also presented.