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Lady beetles rescue pepper plants from aphids

Last fall, a crop of peppers was started in the greenhouse and there was a standing order for biological control agents to be delivered as part of our integrated pest management program. Everything was in place and there should not have been any problems, but then aphids were spotted in the pepper flowers.

Different options for control were considered. Sprays were quickly eliminated as an option since the peppers were going to be eaten and a spraying into the flowers would be difficult. If a biological control agent could be used, it was crucial to find out which aphid was the culprit. The aphid in question turned out to be the foxglove aphid, which is difficult to control biologically. In addition, we used two parasitoids that did not stop the foxglove aphid’s advances. Therefore, the options were limited to releasing the lady beetles.

The convergent lady beetle, Hippodamia convergens, is not grown in a facility, but rather caught in the wild in the western U.S. (typically California) and shipped throughout the U.S. for aphid control. They are an inexpensive, generalist predator (a pint of 9,000 was $50) that prefers aphids, but also consumes scales, thrips and small caterpillars. During their lifetime, one lady beetle can consume 5,000 aphids. One disadvantage is lady beetles do not stay in place without prey to eat.

By the time the lady beetles arrived, the aphid infestation had moved to the rest of the plants. We released half of the lady beetles when they arrived and they immediately colonized the plants. Within a week, our plants were aphid-free. Amazingly, a small number of the lady beetles have stayed in the greenhouse and continued guarding the plants from the aphid invaders.