The polyvalent sequestration ability of an economically important beetle

Area of Science:

• Ecology
• Evolutionary Biology
• Chemical Ecology

Background:

• Specialized herbivores often sequester single classes of toxic plant compounds for protection.
• The ability of herbivores to utilize multiple classes of plant toxins for defense remains largely unexplored.
• Understanding this mechanism is crucial for comprehending multitrophic interactions.

Purpose of the Study:

• To investigate if and how herbivores can utilize multiple classes of plant toxins for self-protection.
• To determine the effectiveness of sequestered mixtures of toxins compared to individual toxins in protecting herbivore offspring.
• To explore the adaptive significance of exploiting plant chemical diversity in herbivore defense.

Main Methods:

• Feeding trials with Diabrotica virgifera beetles on host plants containing different classes of toxins.
• Chemical analysis to identify and quantify sequestered benzoxazinoids, cucurbitacins, glucosinolates, and cyanogenic glycosides in beetles and their eggs.
• Predation assays using generalist predators to assess the protective efficacy of eggs containing single or mixed toxins.

Main Results:

• Diabrotica virgifera beetles selectively sequestered benzoxazinoids, cucurbitacins, and glucosinolates, but not cyanogenic glycosides.
• Sequestered toxins were transferred to eggs, providing protection against generalist predators.
• Eggs containing a mixture of sequestered toxins exhibited enhanced protection compared to eggs with single toxins.

Conclusions:

• Polyphagous herbivores like Diabrotica virgifera can exploit diverse plant chemical defenses by sequestering multiple toxin classes.
• The transfer of mixed toxins to eggs represents a novel adaptive mechanism enhancing offspring survival.
• This strategy contributes to the complex structuring of ecological interactions within multitrophic networks.