ARTHROPOD PREDATORS OF THE PEA APHID, ACYRTHOSIPHON-PISUM HARR (HOM, APHIDIDAE) IN PEAS (PISUM-SATIVUM L), CLOVER (TRIFOLIUM-PRATENSE L) AND ALFALFA (MEDICAGO-SATIVA L)

Arthropod predators of the pea aphid (Acyrtbosiphon pisum Harr.) were collected using pitfall traps in peas (Pisum sativum L.), clover (Trif olium pratense L.) and alfalfa (Medicago sativa L.). Aphid densities w ere monitored using a vacuum suction sampler. Gut dissections were per formed on Coccinella 7-punctata L., Pterostichus melanarius Ill., P. c upreus L. and Bembidion lampros Hbst. to see if they had eaten pea aph ids. When aphid numbers were high, 50-80% of C. 7-punctata had eaten p ea aphids. Few of the carabids ate pea aphids in the field. There was no correlation between numbers of predators caught and numbers of aphi ds at peak in any system. Carabids were more common in peas while spid ers and staphylinids were more common in clover and alfalfa. Colder we ather in 1991 affected both aphid and predator abundance. The importan ce of synchrony in time and space for the predator-prey relationship a re discussed.