Estimating insect pest density using the physiological index of crop leaf

Area of Science:

• Ecology
• Crop Science
• Agricultural Entomology

Background:

• Estimating insect pest population density, like the brown planthopper (BPH), is crucial for crop management but current methods are inefficient.
• BPH infestations in rice cause significant crop losses by feeding on plant sap.
• Physiological changes in host plants due to insect feeding are potential indicators for pest density estimation.

Purpose of the Study:

• To develop a novel, efficient method for estimating brown planthopper (BPH) density in rice plants.
• To investigate the relationship between BPH feeding and physiological changes in rice leaves.
• To create a model for automated and non-professional pest density assessment.

Main Methods:

• Measured physiological traits in rice leaves, including chlorophyll (SPAD), water, silicon, and soluble sugar content.
• Developed four ratio physiological indices comparing BPH-damaged leaves to healthy leaves.
• Constructed a rice growth stage-independent linear model incorporating these indices, damage duration, and population increase rate.

Main Results:

• BPH feeding significantly reduced chlorophyll, water, silicon, and soluble sugar content in rice leaves.
• The four ratio physiological indices showed significant correlation with BPH density.
• The developed linear model demonstrated reasonable accuracy in estimating BPH density.

Conclusions:

• Physiological traits of rice leaves can be effectively used to estimate BPH population density.
• The new method offers a promising alternative to traditional, labor-intensive pest survey techniques.
• This approach facilitates non-professional and automated pest density estimation for improved crop management.