NATURE OF THE CONDITIONING EFFECT ON PECAN BY BLACKMARGINED APHID

Leaves previously exposed to various levels of blackmargined aphid feeding supported fewer aphids than prior unexposed leaves in early- and mid-season, but the reverse occurred in late-season. Blackmargined aphids were smaller from foliage that had supported 349 aphid-days compared to foliage supporting 245 or fewer aphid-days of development. There was no relationship between leaves exposed to heavy prolonged aphid feeding and water potential of the pecan tree. No differences were observed in the pbotosynthetic efficiency between leaves conditioned by blackmargined aphids and leaves kept free of aphid feeding in sleeve cages in the field.