PHENOTYPIC PLASTICITY IN CHOLEVA-AGILIS TO MAINTAIN FITNESS IN AN UNPREDICTABLE ENVIRONMENT (COLEOPTERA, CHOLEVIDAE)

Choleva agilis Illiger 1789 is a cord season species which reproduces and develops in winter months and obligatorily aestivates in the early adult stage from IV until IX. Aestivation delays, and tends to synchr onize, the developmental cycle with the season rather than avoids dete riorating climatic conditions. Females [FF] oviposit for about 150 day s. However, at the end of pre-imaginal development in the spring the a dults emerge within a relatively narrow time interval df about 35 days . Synchronisation of individual development within the population is c aused by the differences in thermal thresholds in subsequent pre-imagi nal stages, and by the changing temperatures during winter months as w ell. The narrow time interval of adult emergence is not maintained unt il the age of first reproduction. By contrast, diapause intensity vari es and gives the capability to spread the onset of reproduction over a time interval of more than 200 days, even between full sibs. Spreadin g the age at first reproduction even within families, and the relative ly low heritability in the duration of diapause (h(2) = 0.12 +/- 0.018 ), are interpreted as bet-hedging mechanisms to cope with the vagaries of weather conditions in an unpredictable environment. Temporal sprea ding of reproduction is so pervasive that it provides the opportunity for at least some daughters of each single dam to match the correct da te of oviposition, independently of birth dates and weather conditions which could be expected in the area of study. There is insufficient s ynchronisation of the developmental cycle with the season by diapause intensity when (a) oviposition is very early in the season, and (b) th e entire pre-imaginal development occurs at extremely high temperature s. Under these circumstances an ecological tuning by photoperiod and t emperature is necessary.