Can the introduction of companion plants increase biological control services of key pests in organic squash?

Florida (USA) is a major producer of squash, Cucurbita pepo L. (Cucurbitaceae), with approximated 16% of the US production in 2019, valued at about 35 million USD. Major insect pests, including the sweetpotato whitefly MEAM1, Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae), and the melon aphid, Aphis gossypii Glover (Hemiptera: Aphididae), jeopardize plant development and transmit viruses of economic importance that can cause up to 50% yield loss in squash crops. Pesticides are generally used for insect management in squash, but the development of insecticide resistance and their non-target effects are major concerns. A combination of non-pesticidal approaches was evaluated, including intercropping flowering plants, augmentation, and conservation biological control to manage key pests in organic squash. Refugia increased natural enemies around the squash; however, only a few beneficial arthropods moved from the companion plants towards the squash plants. Whitefly densities and squash silverleaf ratings were reduced, whereas natural enemies were more abundant when the predatory mite Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) was released alone or together with sweet alyssum, Lobularia maritima (L.) Desv. (Brassicaceae). All companion plants used in this study increased natural enemies, but only African marigolds and sweet alyssum ultimately increased biological control activities.