EGU21-10497
https://doi.org/10.5194/egusphere-egu21-10497
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Is silicon a double-edged sword against insect herbivores? 

Tarikul Islam1,2, Ben D. Moore1, and Scott N. Johnson1
Tarikul Islam et al.
  • 1Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith NSW 2751, Australia (tarikul.islam@westernsydney.edu.au)
  • 2Department of Entomology, Faculty of Agriculture, Bangladesh Agricultural University, Memensingh-2202, Bangladesh (tarikul.entom@bau.edu.bd)

In recent years, silicon (Si) has been increasingly linked to biotic stress management in plants including insect herbivory. The effectiveness of Si against chewing insects is now well recognized. Silicification of plant tissues makes them abrasive and tougher, reducing their masticability and digestibility to insect herbivores. This can cause mandibular wearing of chewers and affect their growth and feeding. Although there has been extensive research on the effects of Si on plant defences (i.e. antixenosis and antibiosis), it remains unclear how feeding on silicified plants affects insect defences to their natural enemies. Insect herbivores show morphological and behavioural defences when encountering predators and parasitoids. For example, lepidopteran larvae can regurgitate, twist the body, or even drop off the plants when attacked by natural enemies. Moreover, insects possess innate immunity (physiological defence) against the attackers, demonstrating cellular and humoral responses upon attack. Notably, there could be potential trade-offs between different defence and immunity traits. Given that feeding on Si-rich plants affects insect growth rates, this could impact their relative investment in different defences, thereby making insects more susceptible to their enemies. We are investigating the effects of Si on plant resistance and tolerance to herbivory and its cascading effects on insect defences to their enemies. We have been growing the model grass, Brachypodium distachyon, a high Si-accumulator, hydroponically with or without Si and examining the effects of Si against the global insect herbivore, Helicoverpa armigera. Our preliminary results suggest that Si supplementation enhances plant antixenotic and antibiotic traits and increases plant tolerance to herbivory. We are currently exploring insect defence and immunity traits when fed on silicified versus non-silicified plants. Our study would shed light on the impacts of Si on insects’ susceptibility to biocontrol agents and provide a better understanding of the effects of Si on insect-plant-natural enemy interactions.

How to cite: Islam, T., Moore, B. D., and Johnson, S. N.: Is silicon a double-edged sword against insect herbivores? , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10497, https://doi.org/10.5194/egusphere-egu21-10497, 2021.