Volatile-mediated oviposition preference for healthy over root-infested plants by the European corn borer

Area of Science:

• Agricultural Science
• Entomology
• Chemical Ecology

Background:

• Oviposition site selection is critical for insect fitness and progeny survival.
• The Preference-Performance hypothesis suggests females choose sites optimal for offspring.
• The impact of root herbivory on the oviposition behavior of other herbivores is poorly understood.

Purpose of the Study:

• To investigate how maize root infestation by Western corn rootworm (WCR) affects European corn borer (ECB) oviposition preference.
• To assess the impact of WCR root infestation on ECB larval performance.
• To explore plant-mediated interactions between above- and below-ground herbivores.

Main Methods:

• Olfactometry and oviposition assays using maize plants with and without WCR root infestation.
• Analysis of plant volatile compounds, specifically identifying upregulated compounds like undecane.
• Larval performance bioassays measuring growth and survival on infested versus healthy plants.

Main Results:

• ECB females exhibited a preference for healthy maize plants, avoiding WCR-infested ones.
• The plant volatile undecane was upregulated in WCR-infested plants and acted as a repellent for ECB oviposition.
• ECB larvae performed significantly better on WCR-infested plants compared to healthy plants, consuming more leaf tissue.

Conclusions:

• Plant root infestation by one herbivore can alter above-ground herbivore oviposition behavior.
• ECB larvae benefit from maize plants stressed by WCR root infestation, contradicting the Preference-Performance hypothesis ('bad motherhood').
• Understanding these below-ground-above-ground herbivore interactions is vital for predicting pest outbreaks and developing integrated pest management strategies.