Continuous production of aphid parasites requires continuously available aphid hosts. Early season greenhouses do not necessarily have any aphids, so greenhouse biocontrol practitioners using aphid parasites have 2 choices: Regularly purchase and release aphid parasites knowing that the parasites will eventually find hosts, or culture aphids purposefully to support parasite reproduction. Fortunately, there are aphid species that will host the parasites but not attack most greenhouse crops. IPM Labs produces two aphid species for this purpose, Rhopalosiphum padi and Acyrthosiphon pisum. R. padi supports Aphidius colemani which controls Myzus persicae (green peach aphid) and Aphis gossypii (melon or cotton aphid). A. pisum supports Aphidius ervi which controls Aulacorthum solani (foxglove aphid) and Macrosiphum euphorbiae (potato aphid). Advantages and disadvantages of the 2 systems are discussed as well as reasons for success or failure.
