Trichomes and spider-mite webbing protect predatory mite eggs from intraguild predation

Area of Science:

• Ecology
• Entomology
• Agricultural Science

Background:

• Predaceous arthropods are more abundant on plants with pubescent or domatia-bearing leaves compared to glabrous leaves.
• Plant pubescence may offer protection to predatory mites from intraguild predation by other arthropods.

Purpose of the Study:

• To test the hypothesis that leaf pubescence protects predatory mite eggs from intraguild predation by western flower thrips (Frankliniella occidentalis).
• To investigate the role of plant topography, including pubescence and webbing, in mediating intraguild predation dynamics.

Main Methods:

• Laboratory experiments using apple leaf pubescence and artificial cotton fibers to simulate trichomes.
• Assessing predation rates of Typhlodromus pyri and Phytoseiulus persimilis eggs by Frankliniella occidentalis on pubescent vs. glabrous surfaces and in Tetranychus urticae webbing.
• Manipulating cotton fiber density to determine its effect on predation.

Main Results:

• Predation by thrips on T. pyri eggs was significantly lower on pubescent apple leaves compared to glabrous leaves.
• Phytoseiid eggs in cotton fibers and T. urticae webbing were preyed upon significantly less by thrips than eggs on bare surfaces.
• Increased cotton fiber density had a minor additional effect on reducing predation.

Conclusions:

• Complex plant leaf topography, including pubescence and webbing, effectively reduces intraguild predation intensity by western flower thrips.
• These findings highlight the importance of plant structural defenses in supporting natural enemy populations in agroecosystems.