Melon aphid (Homoptera: Aphididae) control by inundative convergent lady beetle (Coleoptera: Coccinellidae) release on chrysanthemum

Convergent lady beetles, Hippodamia convergens Guerin-Meneville, collected from aggregations in California were released for control of melon aphids, Aphis Clover, infesting potted chrysanthemum, Dendranthema grandiflora (Tzvelev) 'Hurricane, outdoors. Most beetles dispersed from plants within 1-3 d after a single release during May 1993 and July and September 1993 and 1994. Most dispersing beetles left the study area, although some moved within release plots to adjoining plants or dispersed to nearby plots within approximate to 40 m. Aggregation-collected beetles that were allowed to drink and fly in a screen tent for 7-10 d before release and insectary-reared beetles dispersed more slowly than aggregation-collected beetles that were stored at 4-10 degrees C until the day of release. Although beetles dispersed within days, releases significantly reduced aphid densities during all trials. A single release of 34-42 adult H. convergens per pot provided 25-84% aphid control, calculated according to the Abbott method. Each beetle consumed approximate to 25-170 melon aphids per day. There was a density-dependent functional response in predation; beetles consumed more aphids when released on plants with higher aphid densities. Release of commercially available convergent lady beetles can provide augmentative control of relatively high aphid densities on small potted plants.