Earthworms Help Crops Fight Insects Even When Microplastics Are Present

Greg Howard
6th September, 2024

Earthworms Help Crops Fight Insects Even When Microplastics Are Present

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at Nankai University found that earthworms can help tomato plants grow better in soils contaminated with microplastics (MPs)
  • Earthworms increased the levels of silicon and lignin in damaged tomato leaves, which are important for plant defense against herbivores
  • Earthworms also boosted the plants' antioxidant metabolism, reducing damage from herbivores and helping plants stay healthier under MPs stress
Microplastics (MPs) contamination in agricultural systems is a growing concern due to its potential impacts on soil health and plant growth. A recent study by researchers at Nankai University[1] has shed light on how earthworms can mitigate some of the negative effects of MPs on tomato plants and their interactions with herbivores, specifically the tomato fruitworm, Helicoverpa armigera. Microplastics, tiny plastic particles less than 5mm in size, are pervasive in the environment and have been shown to influence soil carbon dynamics and plant health[2]. This study aimed to explore the ecological risks posed by MPs in agricultural systems by examining both single-organism responses and interactions between different trophic levels. The researchers focused on two common types of MPs: polyethylene (PE) and polypropylene (PP), which are widely used in various plastic products. In their experiment, the team introduced earthworms into soils contaminated with different concentrations of PE and PP MPs (0.02% and 0.2% w/w) to observe the effects on tomato plants and their defense mechanisms against H. armigera. The results demonstrated that earthworms significantly alleviated the inhibitory effects of MPs on tomato growth. This finding is particularly important because MPs have been shown to disrupt soil carbon dynamics and plant growth in previous studies[2]. One of the key findings was that earthworms increased the silicon and lignin content in herbivore-damaged tomato leaves by 19.1% and 57.6%, respectively. Silicon and lignin are crucial for plant structural integrity and defense against herbivores. The presence of earthworms also activated metabolites involved in chemical defense, such as chlorogenic acid, and phytohormones like jasmonic acid, which play vital roles in plant defense signaling pathways. Furthermore, the study found that earthworms effectively reduced oxidative damage induced by H. armigera by promoting antioxidant metabolism in tomato plants. This is significant because oxidative stress can severely impair plant health and productivity. The ability of earthworms to enhance antioxidant metabolism suggests a potential strategy for mitigating the adverse effects of herbivores on plants under MPs stress. The findings of this study align with previous research on plant defense mechanisms. For instance, plants have evolved plastic defense strategies to cope with herbivore attacks, which can vary depending on the herbivore species and the order of attack[3]. The study by Nankai University builds on this understanding by showing that earthworms can influence these defense mechanisms, thereby enhancing plant resilience against herbivores in the presence of MPs. Moreover, the study's results highlight the complex interactions between soil organisms and plant health. Previous research has shown that MPs can affect various soil properties and processes, such as soil organic carbon dynamics and microbial biomass[2]. By incorporating earthworms, the researchers demonstrated that it is possible to mitigate some of these negative effects, suggesting a potential approach for promoting sustainable agriculture. In summary, the study by Nankai University provides valuable insights into the ecological risks of MPs in agricultural systems and offers a promising strategy for mitigating these risks through the use of earthworms. By enhancing plant defense mechanisms and reducing oxidative damage, earthworms can help promote healthier and more resilient crops. This research underscores the importance of considering multi-trophic interactions and the potential benefits of soil organisms in developing sustainable agricultural practices.

AgricultureEnvironmentAnimal Science

References

Main Study

1) Earthworms Enhance Crop Resistance to Insects Under Microplastic Stress by Mobilizing Physical and Chemical Defenses.

Published 5th September, 2024

https://doi.org/10.1021/acs.est.4c04379

Related Studies

2) Global Responses of Soil Carbon Dynamics to Microplastic Exposure: A Data Synthesis of Laboratory Studies.

https://doi.org/10.1021/acs.est.3c06177

3) Plant defence to sequential attack is adapted to prevalent herbivores.

https://doi.org/10.1038/s41477-021-00999-7


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