How does the spider mite affect its host? - briefly
Spider mites pierce plant cells to withdraw sap, causing chlorophyll loss, stippling, and a decline in photosynthetic efficiency. Severe infestations produce leaf yellowing, webbing, and can markedly reduce plant growth and yield.
How does the spider mite affect its host? - in detail
Spider mites feed by piercing plant cells with their stylet and extracting cytoplasmic contents. This action removes essential nutrients, leading to a rapid decline in photosynthetic capacity. Visible symptoms appear as stippling, chlorotic spots, or a fine webbing that covers leaf surfaces. The loss of chlorophyll reduces the plant’s ability to convert light energy, which slows growth and can cause stunted development.
Feeding damage also triggers physiological stress responses. Plants may increase production of defensive chemicals such as jasmonic acid and salicylic acid, diverting resources from growth to defense. Elevated hormone levels can alter leaf morphology, reduce leaf expansion, and accelerate senescence. In severe infestations, the cumulative loss of tissue integrity can cause leaf drop and premature fruit abscission.
Reproduction of the mite is accelerated by the same feeding injury. The nutrient-rich exudate left on the leaf surface serves as a suitable substrate for egg laying, while the webbing provides protection from predators and environmental extremes. High temperatures and low humidity further boost population growth, resulting in exponential increases within a few weeks.
Secondary effects include increased susceptibility to secondary pathogens. Feeding wounds serve as entry points for bacterial and fungal organisms, compounding damage. Moreover, the webbing creates a microclimate that retains moisture, encouraging fungal spore germination and proliferation.
Economic impact is quantified by yield loss, reduced market quality, and increased management costs. Yield reductions can range from 10 % to 80 % depending on crop type, infestation intensity, and timing of attack. Control measures—chemical miticides, biological agents, or cultural practices—require frequent application to keep populations below economic thresholds, thereby adding to production expenses.
Key points of impact:
- Direct loss of photosynthetic tissue → reduced growth and yield.
- Induction of defensive hormone pathways → allocation shift from growth to defense.
- Creation of favorable conditions for mite reproduction → rapid population spikes.
- Facilitation of secondary pathogen infection → compounded damage.
- Economic consequences → diminished harvest quality and elevated control costs.