A newly invasive species may promote dissimilarity of pest populations between organic and conventional farming systems

Bloom, Elias H.; Constancio, Natalie; Hauri, Kayleigh; Szendrei, Zsofia

doi:10.1002/eap.2615

Cited by 4 publications

(4 citation statements)

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“…Although we hypothesized that small-scale organic farms would suffer the highest losses from swede midge because of lack of land for rotation and effective biopesticides, these characteristics did not significantly influence loss in our statistical models. A field study conducted within the same timeframe as our survey in 2018-19 found slightly higher abundance of swede midge on organic farms vs. conventional farms in Michigan (Bloom et al 2022). Surprisingly, only 36% and 41% of survey respondents with known swede midge infestations representing small (<50 acres) and large farms (>50 acres) indicated that this pest was one of their "most problematic pests," respectively.…”

Section: Respondent Characteristicsmentioning

confidence: 57%

Farm-level Losses and Grower Willingness to Try Management Strategies for Swede Midge in Vegetable Crops

Hodgdon¹,

Campbell²,

Conner³

et al. 2022

hortte

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Since its introduction to North America in the 1990s, the invasive swede midge (Contarinia nasturtii) has become an important pest of cruciferous (Brassicaceae) vegetables in the northeast and Great Lakes regions of the United States and the Canadian provinces of Québec and Ontario. Swede midge reduces yield in cruciferous vegetables through larval feeding that distorts growth. Overlapping generations, cryptic larval feeding, and lack of effective biopesticides pose challenges for managing swede midge effectively using current tools. In 2018, we distributed an online survey for commercial vegetable growers in the United States and Canada to measure farm-level economic impacts of swede midge and grower perspectives on new management strategies for this pest. Growers reported losing $3808 US ($4890 Canadian) on average per acre per year due to swede midge–related vegetable crop losses. Both organic and conventional growers expressed an interest in paying more for nonchemical swede midge management vs. insecticides and were interested in trying new management strategies, particularly biological control.

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Section: Respondent Characteristicsmentioning

confidence: 57%

Farm-level Losses and Grower Willingness to Try Management Strategies for Swede Midge in Vegetable Crops

Hodgdon¹,

Campbell²,

Conner³

et al. 2022

hortte

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“…More broadly, greater adoption of sustainable pest management practices could yield environmental benefits for organic farming systems. While organic farms are more ecologically sustainable than conventional farms (Reganold and Wachter, 2016), they represent a spectrum of practices used by different farmers (Bloom et al, 2022). Due to this spectrum, organic and conventional farms can have similar ecological outcomes (e.g., for the conservation of biological control agents) (Orpet et al, 2020).…”

Section: Discussionmentioning

confidence: 99%

“…Multiple studies show organic farms conserve soil microorganisms that promote plant defenses and reduce insect herbivores (Phelan, Mason and Stinner, 1995; Mäder et al, 2002; Phelan, 2009; Mohanram and Kumar, 2019; Blundell et al, 2020; Khatri and Sharma, 2021). Conservation tillage, mulches, cover crops, and organic soil amendments are known to promote pest-suppressive soil microorganisms in organic farms (Alyokhin, Nault and Brown, 2020), yet organic farmers are not homogenous in the practices they use (e.g., farmers use a spectrum of practices under the same certification) (Darnhofer et al, 2010; Bloom et al, 2022). Variation in practices among farmers is further linked with farmer beliefs (Guerin and Guerin, 1994).…”

Section: Introductionmentioning

confidence: 99%

Motivating organic farmers to adopt practices that support the pest-suppressive microbiome relies on understanding their beliefs

Bloom,

Atallah,

Casteel

2024

Renew. Agric. Food Syst.

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Certified organic farming is a suite of regulated practices that can support social, economic, and ecological sustainability in agriculture. Despite the standardization and regulation of certifying bodies, practices adopted by organic farmers vary with potential heterogeneous effects on environmental outcomes. While it is accepted that beliefs can enable or constrain the adoption of farming practices, it remains unclear if variation in organic farmer beliefs mediates observed heterogeneity in practices and the ecology of farms. Communities of soil microorganisms that induce plant resistance and regulate insect herbivores offer a lens to explore the relationship between beliefs and practice adoption. Variation in insect herbivores across organic farms is common but none have studied the role of farmer beliefs in regulating pests through the soil microbiome. Herein, we hypothesized that variation in adoption of microbiome-supportive practices by organic farmers is driven by heterogeneity in their microbiome beliefs. We also investigate the importance of demographic variables and farm characteristics, compared to farmer beliefs, for adoption of practices that support the microbiome. To test our hypothesis, we surveyed the microbiome beliefs, farming practices, and motivations of 85 organic farmers in New York State, USA. We used affinity propagation to cluster farmers by their beliefs, and statistical models to evaluate variation in farming practice adoption and farmer motivations. Our survey received a 30.5% response rate, most organic farmers (≈96%) believed the soil microbiome was important for supporting plant defenses and reducing pests, and <16% believed their farming practices were unimportant for promoting beneficial microbiomes. Seven clusters of farmers were identified that varied in their microbiome beliefs. Among the clusters ≈42% of farmers believed on-farm management and external factors (e.g., climate change) were important for promoting the microbiome. These farmers used fewer pesticides and synthetic mulches, more pre-planting practices (e.g., solarization), and were more motivated to adopt new practices to support the microbiome than their peers. The most important factors motivating adoption were reductions in pests, increased yields, and biodiversity benefits. Beliefs, demographics, and farm characteristics (e.g., time in organic management) were correlated with similar suites of farming practices, but only beliefs predicted farmer motivations. Our study suggests beliefs are key to understanding farmer motivations and promoting organic farming system sustainability via the pest-suppressive microbiome. More broadly, we suggest the need for socio-ecological approaches that account for farmer beliefs when studying the adoption of conservation practices in agroecosystems.

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“…We also evaluated the partial contribution of each bee species, floral species and landscape class to beta diversity at the local ( n = 31) and landscape level ( n = 1079) by applying a jackknife approach (Benito & Birks, 2020; Bloom, Constancio, et al, 2022). This approach consists of removing one bee species, floral species and landscape class at a time and recomputing the partial turnover value for each term in the additive partition of Sørenson's beta diversity (Equations 1 and 2; Baselga, 2010), at both scales (local and landscape level).…”

Section: Methodsmentioning

confidence: 99%

Long‐term organic farming and floral diversity promotes stability of bee communities in agroecosystems

Bloom,

Illán,

Brousil

et al. 2023

Functional Ecology

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Increasing bee diversity promotes pollination services on farms. Yet, given the high turnover in pollinator communities, without knowledge of how pollinator communities assemble, it is difficult to conserve or increase bee diversity. Thus, a mechanistic understanding of factors mediating pollinator community assembly could promote pollinator conservation measures. To assess the determinants of pollinator community assembly and structure, we surveyed bee communities and floral resources on 36 farms ranging from 0 to 43 years in organic production. We used niche‐based and stochastic species abundance models to characterise the mechanisms driving community assembly, and an additive partition of beta diversity to evaluate resource and species turnover (i.e. community structure). We then used statistical models to assess whether resource turnover or time in organic production altered community assembly and beta diversity, and a jackknife analysis to assess the sensitivity of top models to resource and species identity. We show that bee communities on farms that practiced organic methods for longer assembled by niche‐based rather than stochastic processes and had less turnover in bee species across years. Because our model of niche‐based processes assumes resource use, these results indicate bee communities reflect underlying species‐specific resource preferences (e.g. floral and/or nesting resources) and that longer periods of organic management reduced dissimilarity mediated by species replacement. Our jackknife approach then examined the role of species identity effects in beta diversity, showing changes in floral resources increased dissimilarity driven by bee species loss, but only in landscapes simplified by urbanisation. This jackknife analysis then indicated that landscape resource replacement which was not driven by particular landscape classes, mediated bee species replacement wherein dissimilarity was driven by a generalist native bee, suggesting bee life history (e.g. flexibility in resource use) and landscape complementarity, rather than identity, underlie patterns identified using the beta diversity equations. Our results show bee communities assemble by niche‐based processes, evidenced by collinearity in resource and bee species turnover. Because niche‐based assembly indicates ecosystem health, farmers who adopt crop diversification and practice organic methods for longer may promote pollinator diversity and stability leading to improved pollination in farms. Read the free Plain Language Summary for this article on the Journal blog.

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A newly invasive species may promote dissimilarity of pest populations between organic and conventional farming systems

Cited by 4 publications

References 53 publications

Farm-level Losses and Grower Willingness to Try Management Strategies for Swede Midge in Vegetable Crops

Farm-level Losses and Grower Willingness to Try Management Strategies for Swede Midge in Vegetable Crops

Motivating organic farmers to adopt practices that support the pest-suppressive microbiome relies on understanding their beliefs

Long‐term organic farming and floral diversity promotes stability of bee communities in agroecosystems

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