Improved Management of Cotton Aphids in Cotton in the San Joaquin Valley of California: Biology and Implications of Overwintering Sexual Populations

Cotton aphid, Aphis gossypii Glover, is a highly damaging insect pest to several crops in CA, e.g., citrus, cucurbits, cotton, celery, eggplants, nursery plants, etc. This pest, with >300 reported hosts, hinders the agricultural economy by reducing crop yields via removal of crop photosynthates, contaminates commodities with excreted honeydew and insect parts, transmits serious virus diseases, and contributes to increased crop protection costs. In recent years, aphid populations in cotton, which threaten the quality of the harvested lint via the deposition of honeydew, and citrus tristeza virus, an aphid-transmitted virus of citrus, have been severe problems.  Pomegranates are the only identified overwintering/primary host for cotton aphid in CA.  An increase in pomegranate acreage to over 30,000 acres has occurred in recent years. Through these studies, we have been studying several key characteristics of the overwintering biology of this species. Investigations and refinement of management plans for cotton aphid on the overwintering host, pomegranates, may represent a 'weak point' in the life cycle and may offer a unique opportunity to favorably impact management of this key pest.  Biorational insecticides, cultural, and biological approaches are being investigated.