Why do plants affected by spider mites turn yellow and wilt? - briefly
Spider mites pierce leaf cells to extract sap, stripping chlorophyll and impairing water movement, which causes the foliage to yellow. The resulting nutrient loss and reduced transpiration make the plant wilt.
Why do plants affected by spider mites turn yellow and wilt? - in detail
Spider mites feed by piercing leaf cells with their stylet-like mouthparts and extracting the contents of the cytoplasm. This feeding removes chlorophyll‑rich tissue, directly reducing the leaf’s green pigment and causing the characteristic yellowing. The loss of photosynthetic material lowers the plant’s ability to produce carbohydrates, which weakens overall vigor and accelerates tissue collapse.
The damage also disrupts the plant’s water balance. By extracting sap, mites create microscopic wounds that increase transpiration rates. The resulting dehydration reduces turgor pressure in cells, leading to the visible wilting of stems and leaves. Additionally, the plant’s defensive response often involves the production of reactive oxygen species and the accumulation of defensive compounds, which can further impair cellular function and exacerbate chlorosis.
Key physiological effects of spider‑mite infestation include:
- Chlorophyll degradation: feeding removes pigment‑bearing cells, diminishing photosynthetic capacity.
- Reduced carbohydrate synthesis: lower photosynthesis limits energy supply for growth and repair.
- Increased water loss: wounds and altered stomatal regulation accelerate transpiration.
- Cellular stress: defensive signaling pathways divert resources from normal metabolism.
- Secondary pathogen entry: damaged tissue provides entry points for fungi and bacteria, compounding stress.
Collectively, these mechanisms explain why plants attacked by spider mites exhibit both yellow discoloration and loss of rigidity. The combination of nutrient depletion, impaired photosynthesis, and heightened water loss creates a rapid decline in plant health, manifesting as the observed symptoms.