Impact of artificial lights on insects

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Context

• Artificial lights that remain on throughout the night, such as streetlights, can lead to tougher leaves on urban trees, making them less palatable to insects.
• This phenomenon may pose a risk to urban food chains, as revealed in a recent study published in Frontiers in Plant Science.

Details

• The research, titled “Artificial Light at Night Decreases Leaf Herbivory in Typical Urban Areas,” was conducted by University of Chinese Academy of Sciences (Beijing).

Key Findings

Leaf Toughness and Insect Activity:

• The study found that higher illuminance levels correlated with tougher leaves.
• Tougher leaves had fewer signs of insect feeding. In areas with the brightest artificial lighting, there was no evidence of insect damage.

Nutrient and Chemical Changes:

• Artificial light exposure altered nutrient and chemical defense levels in leaves.
• For instance, Japanese pagoda trees exposed to more artificial light showed reduced phosphorus levels in their leaves, which also had less insect damage.

Ecological Implications:

• The study suggests that decreased herbivory could trigger trophic cascading effects in ecosystems.
• Lower insect populations might lead to reduced numbers of insectivorous predators, potentially impacting broader food chains. This trend has the potential to disrupt ecological balance.

Possible Explanations

Photosynthesis Stress:

• Although the exact reasons behind the tree responses to artificial light are unclear, the researchers hypothesize that extended photosynthesis cycles due to continuous light might stress the plants.
• Prolonged photosynthesis can overwhelm trees, possibly leading to detrimental effects on their health.

Conclusion

• The study underscores the need to understand the broader ecological impacts of artificial lighting in urban environments, particularly concerning its effects on plant-insect interactions and food chains.

PRACTICE QUESTION Q. Artificial light exposure has been shown to alter various characteristics in plant leaves. Based on recent studies, which of the following statements is/are correct? 1.Trees exposed to higher levels of artificial light have increased phosphorus levels in their leaves. 2.Reduced phosphorus levels in leaves of trees exposed to artificial light are associated with less insect damage. 3.Increased artificial light exposure has no impact on the nutrient composition of leaves.   Select the correct answer using the code below: a) 1 and 2 only b) 2 only c) 1 and 3 only d) 1, 2, and 3   Answer: b) 2 only Explanation: The study indicates that trees exposed to more artificial light showed reduced phosphorus levels in their leaves. Despite the reduced phosphorus, these leaves also had less insect damage. This suggests that lower phosphorus levels, associated with artificial light exposure, correlate with decreased herbivory by insects. Statement 1 is incorrect because higher levels of artificial light are associated with reduced phosphorus levels in leaves, not increased. Statement 3 is incorrect as the study shows that artificial light exposure does impact the nutrient composition of leaves.

SOURCE: eastmojo