Many ladybird beetles respond to a potential predation event by `reflex bleeding' or secreting a noxious defensive chemical
that is similar to hemolymph. Both adults and larvae show this response. Reflex bleeding is known to reduce predator attack
rates and increase prey survival after an attack, especially when reflex bleeding is employed in combination with other cues
such as odor and warning coloration. In this experiment, we examined how variability in the number of reflex bleeding events
and food quality in the larval stage of the aposematic ladybird beetle
Harmonia axyridis affected elytral color, development time, and terminal size in adults. Effects of reflex bleeding were subtle and may have
been influenced by diet treatments. Adult color did not differ between bleed treatment groups but beetles that reflex bled
tended to take longer to develop and grow to smaller sizes than control group beetles. There were clear and strong effects
of larval diet on adult phenotype: an ad libitum pollen diet resulted in paler adult coloration, shorter development time,
and larger adult size relative to a limited-availability aphid diet. Our results suggest that the best environment for producing
bright-red coloration may not be the best environment for favorable expression of life history characters, especially under
stressful conditions. Interactions between different life history stages of
H. axyridis are also discussed.
Key words Aposematic coloration - Chemical defense - Coccinellidae - Harmonia axyridis - Reflex bleeding
Received: 20 April 1997 / Accepted: 30 September 1997