Avian regulation of crop and forest pests, a meta-analysis

BACKGROUND

Birds have been shown to reduce pest effects on various ecosystem types. This study aimed to synthesize the effect of birds on pest abundance, product damage and yield in agricultural and forest systems in different environments. Our hypothesis is that birds are effective pest regulators that contribute to a reduction in pest abundance, enhancement of yield quality and quantity and economic profit, and that pest regulation may depend on moderators such as the type of ecosystem, climate, pest, and indicator (ecological or economic).

RESULTS

We performed a systematic literature review of experimental and observational studies related to biological control in the presence and absence of regulatory birds. We retained 449 observations from 104 primary studies that were evaluated through qualitative and quantitative analyses. Of the 79 studies with known effects of birds on pest regulation, nearly half of the 334 observations showed positive effects (49%), 46% showed neutral effects, and very few (5%) showed negative effects. Overall effect sizes were positive (mean Hedges' d = 0.38 ± 0.06). A multiple model selection retained only ecosystem and indicator types as significant moderators.

CONCLUSION

Our results support our hypothesis that there is a positive effect of avian control of pests for each analyzed moderator and this effect was significant for both ecological and economic indicators. Avian regulation of pests is a potential effective approach for environmentally friendly pest management that can reduce pesticide use regardless of the context of implementation. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Ground Predator Activity-Density and Predation Rates Are Weakly Supported by Dry-Stack Cow Manure and Wheat Cover Crops in No-Till Maize

Because it keeps land in production, conservation programs that focus on in-field habitat manipulations may help farmers better support predators than by building predator habitat around fields. We investigated two in-field habitat manipulations that benefit producers and soil quality: fertilizing with dry-stack cow manure and planting a wheat cover crop. We hypothesized that, compared with inorganic fertilizer and fallow plots, both treatments augment habitat and residue and support more small arthropods that can serve as alternative prey for larger predators. As a result, we expected manure and the cover crop to increase ground-active predators. In turn, these predators could provide biological control of pests. Each year in a 3-yr field experiment, we applied manure and in 2 yr planted a wheat cover crop. We found that both planting a cover crop and applying dry-stack manure increased the plant cover in May. In the last year, this translated to greater soil mite (Acari) density. At the end of the experiment, however, neither manure nor the wheat cover crop had increased residue on the soil surface. As a result, our treatments had inconsistent effects on predator activity-density, especially for carabids and spiders. We observed strong edge effects from neighboring grass alleys on carabid activity-density. Regardless of treatment, we observed high predation of sentinel prey. We conclude that even without cover crops or organic fertilizer, the stability of no-till maize and increased weeds in fallow treatments generate sufficient habitat complexity and alternative prey to support robust predator communities.

The Promise of a Multi-Disciplinary, Mixed-Methods Approach to Inform Insect Pest Management: Evidence From Wyoming Alfalfa

Pest management strategies involve a complex set of considerations, circumstances, and decision-making. Existing research suggests that farmers are reflexive and reflective in their management choices yet continue to employ curative rather than preventative strategies, and opt for chemical over biological solutions. In this piece, we detail work from a two-year, multidisciplinary, mixed-methods study of insect pest management strategies in alfalfa in Wyoming, integrating data from four focus groups, a statewide survey, and biological sampling of production fields. We outline how these different sources of data together contribute to a more complete understanding of the challenges and strategies employed by farmers, and specifically on biological pest control. We applied this approach across alfalfa hay and seed crop systems. Relatively few farmers acknowledged biological control in focus groups or surveys, yet biological exploration yielded abundant parasitism of common pest alfalfa weevil. On the other hand, parasitism of seed alfalfa pest Lygus was far less common and patchy across fields. It is only in integrating quantitative and qualitative, biological and social data that we are able to generate a more complete portrait of the challenges and opportunities of working with farmers to embrace a preventative paradigm. In doing so, we offer insights on possible barriers to the adoption of preventative insect management strategies and provide a case study of integrating social science and biophysical techniques to better understand opportunities to expand biological pest control in cropping systems.

Ecological intensification and diversification approaches to maintain biodiversity, ecosystem services and food production in a changing world

How do we redesign agricultural landscapes to maintain their productivity and profitability, while promoting rather than eradicating biodiversity, and regenerating rather than undermining the ecological processes that sustain food production and are vital for a liveable planet? Ecological intensification harnesses ecological processes to increase food production per area through management processes that often diversify croplands to support beneficial organisms supplying these services. By adding more diverse vegetation back into landscapes, the agricultural matrix can also become both more habitable and more permeable to biodiversity, aiding in conserving biodiversity over time. By reducing the need for costly inputs while maintaining productivity, ecological intensification methods can maintain or even enhance profitability. As shown with several examples, ecological intensification and diversification can assist in creating multifunctional landscapes that are more environmentally and economically sustainable. While single methods of ecological intensification can be incorporated into large-scale industrial farms and reduce negative impacts, complete redesign of such systems using multiple methods of ecological intensification and diversification can create truly regenerative systems with strong potential to promote food production and biodiversity. However, the broad adoption of these methods will require transformative socio-economic changes because many structural barriers continue to maintain the current agrichemical model of agriculture.