The effect of squash domestication on a belowground tritrophic interaction

Area of Science:

• Plant-herbivore interactions
• Chemical ecology
• Evolutionary biology

Background:

• Plant domestication often leads to loss of defense compounds.
• Squash domestication 10,000 years ago reduced toxic cucurbitacins.
• Banded cucumber beetles sequester cucurbitacins, but their defensive role is unclear.

Purpose of the Study:

• Investigate the impact of squash domestication on chemical defense of banded cucumber beetle larvae against predators.
• Examine the role of sequestered cucurbitacins in protecting larvae from rove beetles.
• Explore belowground tritrophic interactions in the context of plant domestication.

Main Methods:

• Larval feeding trials on domesticated and wild squash varieties.
• Quantification of cucurbitacin content in plant tissues.
• Assessing predation rates by rove beetles on herbivore larvae.

Main Results:

• Cucurbitacins did not confer protection to banded cucumber beetle larvae against predatory rove beetles.
• Larvae feeding on cucurbitacin-free domesticated squash experienced less predation than those on high-cucurbitacin wild squash.
• Predation avoidance may be inversely related to cucurbitacin sequestration.

Conclusions:

• Sequestered cucurbitacins do not protect banded cucumber beetle larvae from rove beetle predation.
• Plant domestication has altered belowground tritrophic interactions.
• A trade-off may exist between coping with plant toxins and avoiding predation.