scholarly journals A meta-analysis of crop pest and natural enemy response to landscape complexity

2011 ◽  
Vol 14 (9) ◽  
pp. 922-932 ◽  
Author(s):  
Rebecca Chaplin-Kramer ◽  
Megan E. O’Rourke ◽  
Eleanor J. Blitzer ◽  
Claire Kremen
Keyword(s):  
Natural Enemy ◽  
Meta Analysis ◽  
Landscape Complexity ◽  
Crop Pest

scholarly journals Pest control of aphids depends on landscape complexity and natural enemy interactions

PeerJ ◽  
2015 ◽  
Vol 3 ◽  
pp. e1095 ◽  
Author(s):  
Emily A. Martin ◽  
Björn Reineking ◽  
Bumsuk Seo ◽  
Ingolf Steffan-Dewenter
Keyword(s):  
Pest Control ◽  
Natural Enemy ◽  
Landscape Complexity

scholarly journals Enemies mediate distance- and density-dependent mortality of tree seeds and seedlings: a meta-analysis of fungicide, insecticide and exclosure studies

2021 ◽  
Vol 288 (1943) ◽  
pp. 20202352
Author(s):  
Xiaoyang Song ◽  
Richard T. Corlett
Keyword(s):  
Density Dependence ◽  
Natural Enemies ◽  
Natural Enemy ◽  
Plant Pathogens ◽  
Meta Analysis ◽  
Seedling Stage ◽  
Forest Community ◽  
Density Dependent ◽  
Density Dependent Mortality ◽  
Dependent Mortality

Conspecific negative distance- and density-dependence is often assumed to be one of the most important mechanisms controlling forest community assembly and species diversity globally. Plant pathogens, and insect and mammalian herbivores, are the most common natural enemy types that have been implicated in this phenomenon, but their general effects at different plant life stages are still unclear. Here, we conduct a meta-analysis of studies that involved robust manipulative experiments, using fungicides, insecticides and exclosures, to assess the contributions of different natural enemy types to distance- and density-dependent effects at seed and seedling stages. We found that distance- and density-dependent mortality caused by natural enemies was most likely at the seedling stage and was greater at higher mean annual temperatures. Conspecific negative distance- and density-dependence at the seedling stage is significantly weakened when fungicides were applied. By contrast, negative conspecific distance- and density-dependence is not a general pattern at the seed stage. High seed mass reduced distance- and density-dependent mortality at the seed stage. Seed studies excluding only large mammals found significant negative conspecific distance-dependent mortality, but exclusion of all mammals resulted in a non-significant effect of conspecifics. Our study suggests that plant pathogens are a major cause of distance- and density-dependent mortality at the seedling stage, while the impacts of herbivores on seedlings have been understudied. At the seed stage, large and small mammals, respectively, weaken and enhance negative conspecific distance-dependent mortality. Future research should identify specific agents of mortality, investigate the interactions among different enemy types and assess how global change may affect natural enemies and thus influence the strength of conspecific distance- and density-dependence.

scholarly journals Meta-analysis of tree diversity effects on the abundance, diversity and activity of herbivores' enemies

2021 ◽  
Author(s):  
Alex Stemmelen ◽  
Hervé Jactel ◽  
Eckehard Brockerhoff ◽  
Bastien Castagneyrol
Keyword(s):  
Natural Enemies ◽  
Natural Enemy ◽  
Meta Analysis ◽  
Mixed Forest ◽  
Forest Tree ◽  
Tree Diversity ◽  
Enemies Hypothesis ◽  
Natural Enemies Hypothesis ◽  
Abundance And Diversity ◽  
Diversity Effects

The natural enemies hypothesis predicts that the abundance and diversity of antagonists such as predators and parasitoids of herbivores increases with the diversity of plants, which can lead to more effective top-down control of insect herbivores. However, although the hypothesis has received large support in agricultural systems, fewer studies have been conducted in forest ecosystems and a comprehensive synthesis of previous research is still lacking. We conducted a meta-analysis of 65 publications comparing the diversity, abundance or activity of various groups of natural enemies (including birds, bats, spiders and insect parasitoids) in pure vs. mixed forest stands. We tested the effects of forest biome, natural enemy taxon and type of study (managed vs experimental forest). We found a significant positive effect of forest tree diversity on natural enemy abundance and diversity but not on their activity. The effect of tree diversity on natural enemies was stronger towards lower latitudes but was not contingent on the natural enemy taxon. Overall, our study contributes substantially toward a better understanding of the natural enemies hypothesis in forest systems and provides new insights about the mechanisms involved. Furthermore, we outline potential avenues for strengthening forest resistance to the growing threat of herbivorous insects.

A mathematical study of a crop-pest-natural enemy model with Z-type control

2021 ◽  
Author(s):  
Dibyendu Sekhar Mandal ◽  
Abdennasser Chekroun ◽  
Sudip Samanta ◽  
Joydev Chattopadhyay
Keyword(s):  
Natural Enemy ◽  
Mathematical Study ◽  
Crop Pest

scholarly journals Meta-analysis reveals that seed-applied neonicotinoids and pyrethroids have similar negative effects on abundance of arthropod natural enemies

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2776 ◽  
Author(s):  
Margaret R. Douglas ◽  
John F. Tooker
Keyword(s):  
Biological Control ◽  
Natural Enemies ◽  
Natural Enemy ◽  
Control Function ◽  
Meta Analysis ◽  
Field Studies ◽  
Target Species ◽  
Crop Species ◽  
Pyrethroid Insecticides ◽  
Toxin Exposure

BackgroundSeed-applied neonicotinoids are widely used in agriculture, yet their effects on non-target species remain incompletely understood. One important group of non-target species is arthropod natural enemies (predators and parasitoids), which contribute considerably to suppression of crop pests. We hypothesized that seed-applied neonicotinoids reduce natural-enemy abundance, but not as strongly as alternative insecticide options such as soil- and foliar-applied pyrethroids. Furthermore we hypothesized that seed-applied neonicotinoids affect natural enemies through a combination of toxin exposure and prey scarcity.MethodsTo test our hypotheses, we compiled datasets comprising observations from randomized field studies in North America and Europe that compared natural-enemy abundance in plots that were planted with seed-applied neonicotinoids to control plots that were either (1) managed without insecticides (20 studies, 56 site-years, 607 observations) or (2) managed with pyrethroid insecticides (eight studies, 15 site-years, 384 observations). Using the effect size Hedge’sdas the response variable, we used meta-regression to estimate the overall effect of seed-applied neonicotinoids on natural-enemy abundance and to test the influence of potential moderating factors.ResultsSeed-applied neonicotinoids reduced the abundance of arthropod natural enemies compared to untreated controls (d= −0.30 ± 0.10 [95% confidence interval]), and as predicted under toxin exposure this effect was stronger for insect than for non-insect taxa (QM= 8.70, df = 1,P= 0.003). Moreover, seed-applied neonicotinoids affected the abundance of arthropod natural enemies similarly to soil- or foliar-applied pyrethroids (d= 0.16 ± 0.42 or −0.02 ± 0.12; with or without one outlying study). Effect sizes were surprisingly consistent across both datasets (I2 = 2.7% for no-insecticide controls;I2 = 0% for pyrethroid controls), suggesting little moderating influence of crop species, neonicotinoid active ingredients, or methodological choices.DiscussionOur meta-analysis of nearly 1,000 observations from North American and European field studies revealed that seed-applied neonicotinoids reduced the abundance of arthropod natural enemies similarly to broadcast applications of pyrethroid insecticides. These findings suggest that substituting pyrethroids for seed-applied neonicotinoids, or vice versa, will have little net affect on natural enemy abundance. Consistent with previous lab work, our results also suggest that seed-applied neonicotinoids are less toxic to spiders and mites, which can contribute substantially to biological control in many agricultural systems. Finally, our ability to interpret the negative effect of neonicotinoids on natural enemies is constrained by difficulty relating natural-enemy abundance to biological control function; this is an important area for future study.

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