Habitat manipulation to mitigate the impacts of invasive arthropod pests

Jonsson, Mattias; Wratten, Stephen D.; Landis, Doug; Tompkins, Jean; Cullen, Ross

doi:10.1007/s10530-010-9737-4

Cited by 68 publications

(49 citation statements)

References 107 publications

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“…In particular, the number of flowers within gardens directly negatively affected aphid densities, but counter to our predictions did not directly affect parasitism. This contrasts with previous studies of parasitism in rural agricultural systems where parasitism increases with agroecosystem floral availability (Jonsson, Wratten, Landis, Tompkins, & Cullen, 2010), but supports other findings that local factors including floral availability have no direct effect on parasitism in urban systems (Hanks & Denno, 1993;Dale & Frank, 2014;Lowenstein, Gharehaghaji, & Wise, 2017). Flowers may, however, instead attract other aphidophagous predators that are negatively affecting aphid densities.…”

Section: Influence Of Garden Management Factors On Herbivore-parasitocontrasting

confidence: 51%

Herbivore regulation in urban agroecosystems: Direct and indirect effects

Egerer

Liere

Lin

et al. 2018

Basic and Applied Ecology

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Urban agroecosystems can provide habitat for biodiversity and can benefit human communities through urban food provisioning. Moreover, urban agroecosystems could be managed so as to optimize ecosystem services like natural pest control provided by trophic interactions between natural enemies and herbivores. As in other ecosystems, predation and parasitism regulate herbivores in urban settings, but less is known about the relative importance of direct and indirect effects at local and landscape scales in highly managed urban agroecosystems. We collected data on herbivore (cabbage aphid) density and parasitism ratios (proportion of parasitized aphid "mummies") in 25 community gardens in three counties in the California central coast, USA. We used structural equation modeling to examine the effects of direct factors (host plant characteristics and parasitism) and indirect factors (soil, garden, and landscape characteristics) on herbivore density changes at two time points in the growing season (June and August). Aphid density, but not parasitism, varied across counties over the season, and there was a strong negative relationship between aphid density and parasitism. Direct effects were strong drivers of aphid density but not parasitism. In June, aphid density increased with host plant volume but decreased with greater floral density, while parasitism was only influenced by aphid density. In August, host plant volume similarly positively affected aphid density, and soil water holding capacity increased host plant volume. In addition, host plant density had a strong negative effect on parasitism. Urban gardeners may be able to reduce aphid pest densities by increasing floral resource density and strategically spatially distributing host plants throughout garden beds, though these processes depend on the season. The indirect effects of soil water holding capacity on aphid densities further suggest a critical role of human management on pest populations and pest control services through soil amendments and irrigation.

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Section: Influence Of Garden Management Factors On Herbivore-parasitocontrasting

confidence: 51%

Herbivore regulation in urban agroecosystems: Direct and indirect effects

Egerer

Liere

Lin

et al. 2018

Basic and Applied Ecology

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“…In this respect, the important factor in the evaluation of landscape effects might be initial complexity of landscape structure. Jonsson et al (2010) and Tscharntke et al (2012) favoured bell shaped parasitism rate-complexity relationships with the consequence that we should expect detectable parasitoid biocontrol effects only at intermediate levels of landscape complexity. We note that agricultural intensification in Poland was comparably low during the last 20 years.…”

Section: Discussionmentioning

confidence: 96%

Landscape structure and agricultural intensification are weak predictors of host range and parasitism rate of cereal aphids

Hawro

Ceryngier

Kowalska

et al. 2016

Ecological Research

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Landscape structure and agricultural intensification are weak predictors of host range and parasitism rate of cereal aphids Abstract Proportions of specialist and generalist primary parasitoids have been described by the resource breadth and the trade-off hypothesis. These alternative hypotheses predict either decreased or increased, respectively, parasitism rate of shared aphid species by specialist parasitoids. We tested both hypotheses and the confounding effects of landscape structure and agricultural intensification (AI) using extensive samplings of aphids and their parasitoids in Polish agricultural landscapes. Abundances, species composition of aphids, primary parasitoids, and parasitism rate of aphids by specialists and generalist parasitoids were analysed. Contrary to our expectations we found equally decreased parasitism rates by both types of primary parasitoids at higher aphid densities and thus proportion of specialists to generalists did not change with increasing host density. In line with the resource breadth hypothesis, specialist parasitoids had always lower abundances and parasitism rates than generalist parasitoids. Landscape diversity and agricultural intensification did not influence the host-parasitoid population dynamics. We speculate that these contrasting results could be caused by the additional density effects of secondary parasitoids. We conclude that simplistic two-trophic-level population models are not able to fully describe the complex dynamics of trophic networks. We also argue that agricultural intensification has lower effects on abundance and effectiveness of parasitoids than predicted by respective predator-prey models and empirical studies performed in controlled and artificial conditions.

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“…An increase in woody richness may have provided more species of alternative prey (e.g., aphids) for ladybeetles in the trees, potentially lowering our ability to find ladybeetles in the herbaceous vegetation (the strata where our sampling took place). Increases in floral abundance may have provided more pollen and nectar resources, often food resources for ladybeetles, but promoting floral abundance to attract ladybeetles for biological control could be used with caution since increasing floral abundance may lower predation rate in some agricultural settings [36]. One other study in the same California sites noted lower ladybeetle species richness in smaller gardens [14].…”

Section: Natural Enemiesmentioning

confidence: 99%

“…First, we found that floral abundance had positive effects on both ladybeetle abundance and egg removal. Although increases in ladybeetle abundance might increase predation, increased floral abundance may detract from the impact of ladybeetles as predators [36]. Second, mulch cover increased the abundance of parasitoids in both locations and enhanced egg predation in California.…”

Section: Recommendationsmentioning

confidence: 99%

Agroecological Pest Management in the City: Experiences from California and Chiapas

et al. 2018

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Urban gardens are a prominent part of agricultural systems, providing food security and access within cities; however, we still lack sufficient knowledge and general principles about how to manage pests in urban agroecosystems in distinct regions. We surveyed natural enemies (ladybeetles and parasitoids) and conducted sentinel pest removal experiments to explore local management factors and landscape characteristics that influence the provisioning of pest control services in California, USA, and Chiapas, Mexico. We worked in 29 gardens across the two locations. In each location, we collected data on garden vegetation, floral availability, ground cover management, and the percentage of natural, urban, and agricultural land cover in the surrounding landscape. We sampled ladybeetles, Chalcidoidea, and Ichneumonoidea parasitoids with sticky traps, and monitored the removal of three different pest species. Ladybeetle abundance did not differ between locations; abundance decreased with garden size and with tree cover and increased with herbaceous richness, floral abundance, and barren land cover. Chalcicoidea and Ichneumonoidea parasitoids were more abundant in Chiapas. Chalcicoidea abundance decreased with herbaceous richness and with urban cover. Ichneumonoidea abundance increased with mulch and bare ground cover, garden size, garden age, and with agriculture land cover but decreased with tree richness and urban cover. Predators removed between 15-100% of sentinel prey within 24 h but prey removal was greater in California. Generally, prey removal increased with vegetation diversity, floral abundance, mulch cover, and urban land cover, but declined with vegetation cover and bare ground. Although some factors had consistent effects on natural enemies and pest control in the two locations, many did not; thus, we still need more comparative work to further develop our understanding of general principles governing conservation biological control in urban settings.

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Habitat manipulation to mitigate the impacts of invasive arthropod pests

Cited by 68 publications

References 107 publications

Herbivore regulation in urban agroecosystems: Direct and indirect effects

Herbivore regulation in urban agroecosystems: Direct and indirect effects

Landscape structure and agricultural intensification are weak predictors of host range and parasitism rate of cereal aphids

Agroecological Pest Management in the City: Experiences from California and Chiapas

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