Related Experiment Video
Updated: Jun 14, 2026
10:14
Double-stranded RNA Oral Delivery Methods to Induce RNA Interference in Phloem and Plant-sap-feeding Hemipteran Insects
Published on: May 4, 2018
14.0K
Defoliation-induced changes in foliage quality may trigger broad-scale insect outbreaks
Louis De Grandpré1, Maryse Marchand2, Daniel D Kneeshaw3
1Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, Quebec City, QC, Canada. louis.degrandpre@canada.ca.
Communications Biology
|May 16, 2022
Summary
Insect herbivory can create a positive feedback loop, enhancing forest nutrient availability and improving plant quality. This boosts insect populations, leading to more severe and self-amplifying outbreaks.
Area of Science:
- Ecology
- Forestry
- Entomology
Background:
- Insect outbreaks are influenced by top-down (predation) and bottom-up (host nutrition) factors.
- Insect defoliation can alter host plant nutritional quality, potentially impacting future outbreaks.
Purpose of the Study:
- To evaluate the hypothesis that herbivory enhances plant nutritional quality through nutrient cycling, creating a positive feedback loop for insect outbreaks.
- To investigate the relationship between spruce budworm outbreaks, forest nutrient dynamics, and host tree foliage quality.
Main Methods:
- Quantified litter nutrient fluxes, soil nitrogen availability, and host tree foliar nutrient status over seven years during a spruce budworm outbreak.
- Assessed these parameters along a forest susceptibility gradient.
Main Results:
- Soil nutrient fluxes and nitrogen availability increased as the spruce budworm outbreak progressed.
- Foliar nutrient status improved in surviving host trees, indicating enhanced plant quality.
- These changes correlate with increased insect fitness, population density, and defoliation levels.
Conclusions:
- Defoliation can create a positive bottom-up feedback in forest ecosystems by increasing nutrient availability.
- This feedback loop fosters conditions conducive to self-amplifying insect herbivore population dynamics and large-scale outbreaks.
Related Concept Videos
01:50Threats to Biodiversity
There have been five major extinction events throughout geological history, resulting in the elimination of biodiversity, followed by a rebound of species that adapted to the new conditions. In the current geological epoch, the Holocene, there is a sixth extinction event in progress. This mass extinction has been attributed to human activities and is thus provisionally called the Anthropocene. In 2019 the human population reached 7.7 billion people and is projected to comprise 10 billion by...
01:21Frequency-dependent Selection
When the fitness of a trait is influenced by how common it is (i.e., its frequency) relative to different traits within a population, this is referred to as frequency-dependent selection. Frequency-dependent selection may occur between species or within a single species. This type of selection can either be positive—with more common phenotypes having higher fitness—or negative, with rarer phenotypes conferring increased fitness.Positive Frequency-Dependent SelectionIn positive...
02:26Defenses Against Pathogens and Herbivores
Plants present a rich source of nutrients for many organisms, making it a target for herbivores and infectious agents. Plants, though lacking a proper immune system, have developed an array of constitutive and inducible defenses to fend off these attacks.
02:26Ecological Disturbance
An ecological disturbance is a temporary disruption in the environment resulting from abiotic, biotic, or anthropogenic factors, causing a pronounced change in an ecosystem. The impact of an ecological disturbance, which can depend on its intensity, frequency, and spatial distribution, plays a significant role in shaping the species diversity within the ecosystem.Ecological disturbances can be caused by an event as small as the trampling of underbrush to an incident as wide-ranging as a forest...
01:17Hypothesis: Accept or Fail to Reject?
The outcome of any hypothesis testing leads to rejecting or not rejecting the null hypothesis. This decision is taken based on the analysis of the data, an appropriate test statistic, an appropriate confidence level, the critical values, and P-values. However, when the evidence suggests that the null hypothesis cannot be rejected, is it right to say, 'Accept' the null hypothesis?
There are two ways to indicate that the null hypothesis is not rejected. 'Accept' the null hypothesis and 'fail to...
There are two ways to indicate that the null hypothesis is not rejected. 'Accept' the null hypothesis and 'fail to...
01:09Microbe-Plant Interactions
Microbe-plant interactions represent a dynamic spectrum of associations shaped by intricate chemical signaling. These interactions can be neutral, beneficial, or detrimental, and profoundly influence plant physiology, growth, and ecosystem function. The plant microbiome, comprising bacteria, fungi, archaea, protists, and viruses, plays a pivotal role in mediating these effects through surface colonization, internal colonization, or systemic symbiosis.Mutualistic associations, particularly with...