Influence of egg size on egg and larval development of Sympetrum striolatum at different prey availability (Odonata: Libellulidae)

Abstract

Egg size differences might have an important influence on reproductive success because they may lead to different offspring conditions, hatching date or larval size. We presumed that egg size in odonates positively correlates with egg development time, and larger eggs lead to larger larvae. However, we assumed that the size benefit could only be maintained under harsh, but not under good conditions. Harsh and good conditions were simulated by different diets with specific feeding intervals; high prey level fed every day, low prey level fed every second day. The prey organisms used were Artemia salina and Chironomus riparius. The study was conducted with the libellulid Sympetrum striolatum. Our results showed that larger eggs caused a longer development time. Larger eggs resulted in significantly larger first instar larvae. However, larger larvae maintained their size benefit only in the high prey level with C. riparius. We found no significant differences between low prey and high prey level within the two prey types. We therefore assume that the differences between the two prey levels in this study were not large enough. In general, A. salina seems to be more nutrious than C. riparius for the first larval stadia.

Keywords: Odonata, Dragonfly, egg size, larval size, egg development time, prey, Anemia salina, Chironomus riparius

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