Symposium 1: Biodiversity and Ecological Processes in Agroecosystems
Organized by: I Perfecto and A Power
Monday, August 4. 8:00 AM to 11:30 AM, SITCC Oglethorpe Auditorium.

Biological control of red scale.

Murdoch, William*,1, Swarbrick, Susan1, Briggs, Cheryl2, 1 University of California, Santa Barbara, CA2 University of California, Berkeley, CA

ABSTRACT- In most cases of successful biological control there is likely to be more than one natural enemy that attacks the pest. Credit for control is sometimes given to just one of these enemies, and in others it has been argued that the multiple enemies are in some way complementary, and perhaps even essential to control. This is a difficult issue to resolve. We created experimental outbreaks of California red scale, a pest of citrus whose successful control in southern California requires Aphytis melinus. We have shown that Aphytis responded to increased scale density and that the mortality it imposed can account for outbreak suppression. It appears that the other agents present did not respond, or not adequately, to increased scale density. The other enemies may, however, have an important effect on control by increasing red scale ?background? death rate. We are investigating this possibility in a model of the system.

Key words: biological control, parasitoids, regulation