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

Abstract

Florida 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 (Bemisia tabaci Genn., MEAM1; Hemiptera: Aleyrodidae) and the melon aphid (Aphis gossypii Glover, Hemiptera: Aphididae) jeopardizes plant development and transmit viruses of economic importance that can cause up to 50% yield loss in organic squash crops.Pesticides are generally used for insect management in conventional squash, but the development of insecticide resistance and their non-target effects are major concerns. Organic growers have limited pest management tactics for insect pest management since pesticides are not allowed. 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, while natural enemies were more abundant when the predatory mite Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) was released alone or together with sweet alyssum.All companion plants used in this study increased natural enemies, but only African marigolds and sweet alyssum ultimately increased biological control activities.

Effects of intercropping marigold, cowpea and an insecticidal soap on whiteflies and aphids in organic squash

“…Aphids can reproduce parthenogenically all year round in Florida; thus, it is not surprising that aphids were present from September to November. Our findings confer with Lopez and Liburd (2022), showing a higher aphid population when squash was planted next to cowpea. The high density of aphids justifies the higher presence of coccinellids in the cowpea, including D. catalinae , C. septempunctata , Cy.…”

“…In the first year of our study, intercropping squash with marigold increased marketable yields by 58%; with cowpea by 43%; and with the mixed treatment by 37% compared with the control plots. Previous studies have also shown significantly higher squash yields when grown with and after legumes (Peoples et al, 1995; Sant'Anna et al, 2018) and when grown alongside marigolds (Lopez & Liburd, 2022). A higher number of predators and parasitoids found in the diversified treatments may have indirectly influenced the higher proportion of marketable squash yields through their biological control services on nymphal whiteflies.…”

“…These coccinellids have been shown to be effective suppressants of aphids (Bista & Omkar., 2013; Isikber, 2005; Khan & Zaki, 2007; Razze et al, 2016; Sharma et al, 1991). Coccinellids have also been observed in high numbers when cabbage and squash were intercropped with cowpea (Borkakati et al, 2019; Lopez & Liburd, 2022). Through in situ counts and YST, we show that marigold and cowpea plots supported a higher density of parasitoids than the control for both years.…”

“…Intercropping interrupts the visual orientation of insects from the host plant and can introduce plant chemical volatiles that interfere with olfactory‐driven host‐finding mechanisms (Andow, 1991; Smith & McSorley, 2000). Although intercropping is widely adopted in organic vegetable production systems, very few studies have documented the benefits of managing pests of squash (Kopittke et al, 2012; Lopez & Liburd, 2022).…”

“…African marigolds ( Tagetes erecta L., Asteraceae) have been used as companion plants and cover crops to increase soil quality and enhance beneficial arthropod communities in diversified cropping systems (Bakshi & Ghosh, 2022; Hooks et al, 2010; Zavaleta‐Mejia & Gomez, 1995). Intercropping marigold has been shown to suppress pests on the cash crop by increasing biological control activities (Iamba & Teksep, 2021; Lopez & Liburd, 2022; Silveira et al, 2009; Souza et al, 2019). Cowpea ( Vigna unguiculata (L.) Walp.…”