Youngsung Joo, from Seoul National University, discusses the effects of climate change on plant-herbivore interactions, with a focus on endangered insect species and their host plants.
Climate change poses a threat to biodiversity. More than 70 percent of endangered species are insects and plants, with about 70 percent of insects relying on plant materials as food. So, climate change can directly affect insect species and also indirectly impact them through changes in their host plants.
The effects of climate change on host plants’ growth and nutrition are then crucial for estimating the future population of endangered insect species.
Studies suggest that increased carbon dioxide levels can act as a fertilizer and positively affect plant growth, potentially increasing food quantity for herbivores. However, the nutrition dilution hypothesis proposes that higher carbon dioxide levels may lead to a decrease in food quality for herbivores due to imbalances between carbon and nitrogen in host plants. Toxicity of plants is another important factor for herbivores, but limited research has been done on how climate change affects this aspect.
A study on a specific endangered species of butterfly and its host plant (Aristolochia contorta) indicates that climate change, with elevated carbon dioxide levels and altered soil moisture content, negatively affects the plant’s growth, nutrition, and production of secondary metabolites (toxic compounds). The negative effects of climate change on the butterfly’s growth will be partially mitigated by increased soil moisture.
Variation in time
Also, the interaction between plants and insects occurs multiple times per year, and the effects of climate change can vary over time, with some effects being neutralized after the first year.
However, climate change also leads to increased growth of generalist herbivores, potential competitors of the endangered species, which can negatively impact the future population of the endangered species through increased competition. Overall, the effects of climate change on host plants negatively affect the future population of endangered insect species.
In summary, it is important to understand the complex interactions between climate change, host plants, and herbivores to be able to predict the impact on endangered species and biodiversity as a whole.