Changes in infestation rate and age structure of Dermanyssus hirundinis and Ornithonyssus sylviarum (Acarina) during nidification and breeding period of penduline tit.

Populations of 2 parasitic mites, Dermanyssus hirundinis (Hermann) (63,169 collected individuals) and Ornithonyssus sylviarum (Canestrini et Fanzago) (3,425 collected individuals), in 305 penduline tit, Remiz pendulinus L., nests were studied in 1993 and 1994. The nests were divided into 4 groups: nests without eggs, nests with eggs, nests with nestlings, and nests just after fledging. The average percentage of infested nests increased from the nests without eggs to the nests after fledging (at 20% in both years of investigation), and the increase of mite abundance was exponential. Presence of nestlings in the nests stimulated intensive reproduction of parasitic mites. An increasing infestation intensity in nests was observed during the host breeding period. The 2 mite species exhibited similar age structure patterns in the nests of all the groups and during the entire penduline tit breeding period as well. A decrease in the proportion of adult mites (mainly females) and an increase of nymphs (above all of protonymphs) occurred at the time of fledging and at the end of host breeding period. The percentage of the ovigerous females increased in the individual nests, but decreased during the breeding period of penduline tit. The quantitative parameters of D. hirundinis populations in the highly infested nests depended on the individual nidification and nidobiology of the host, whereas the qualitative parameters (age structure) of these populations depended more on abiotic factors and life strategy of the ectoparasite.