Objectives
In Heteroptera, only a small number of species
overwinter at the nymphal stages. A scutellerid
bug, Poecilocoris lewisi, overwinters at
final (5th) instar nymphs. In addition, adult
females show considerably long pre-oviposition
period in nature.
This study aims to clarify the seasonal adaptations
of this species with reference to
1) photoperiodic responses of nymphs and
adults,
2) geographical variation in those responses
among three local populations, and
3) ecological significance of the adult photoperiodic
response in relation to their host plant
phenology.
Conclusions
The final (5th) instar nymphs entered diapause
under short-day conditions. The higher the
latitude where they were collected, the longer
was the critical daylength for the induction
of the nymphal diapause.
Adult females showed longer pre-oviposition
periods under long-day conditions than those
under short-day conditions. It is considered
that adult females enter reproductive diapause,
although the difference was very small in
Aomori population.
In Osaka, seed weight of the host plant,
Cornus controversa, reached maximum in early
July. This is why females start oviposition
in this season.