Trichomes on Cotton Leaf Surface Affect the Feeding Behaviors of Cotton Aphids (Aphis gossypii)

Aphis gossypii Glover is one of the most important pests in cotton seedling. The specialized mouthpart and short generation time made them seriously restricted the cotton yield. With the electrical penetration graph (EPG), optical microscope, and scanning electron microscope, the physical characteristics of trichomes on the cotton leaf surface and their effects on the stylet penetration behaviors of cotton aphids were investigated in this study. Two types of leaf trichomes, glandular trichomes, and asteroid non-glandular trichomes were observed on the surface of cotton leaves under optical and scanning electron microscopes. As a whole, EPG results mainly showed differences in non-probing period which meant searching on the leaf surface, and potential drop waveform which meant intracellular punctures. Whereas pathway waveform, xylem ingestion waveform, and phloem ingestion waveform showed inconspicuous differences. Detailed indicators were slightly different at different periods. Our results suggested that the structure of trichomes may affect the searching behaviors of herbivorous insect pests and hence regulate the plant-environment interactions.