A case of abnormal size in eggs and larvae of the Taiga tick, Ixodes persulcatus (Acari: Ixodidae).

Egg batches laid by females of Ixodes persulcatus (maintained under a photoperiod of L:D 20:4 before feeding) contained eggs of two sizes: numerous normal eggs of 0.578 x 0.421 mm and some giant eggs of 0.776 x 0.515 mm. Giant eggs were 32-34% greater in length and 22-24% greater in width than normal eggs. Females maintained under a short-day photoperiod (L:D 12:12) laid only normal eggs (0.588 x 0.417 mm). There were no differences between these eggs in viability and developmental time, but larvae hatched from giant eggs were larger (length of body 23-28% greater and of gnathosoma 12-15% greater) than larvae from normal eggs. This dimorphism of eggs and larvae was not sex determined, but may be a maternal photoperiodic effect.