Periodic Reporting for period 1 - BISEM (Biological Impact of Benzoxazinoid Metabolization by a Specialist Root Herbivore)
Reporting period: 2021-06-01 to 2023-05-31
Some herbivores can sequester and use plant secondary metabolites for their own defense. Despite many examples of sequestration, the impact of these compounds on herbivore performance is still not well understood, especially for root feeding insects. Diabrotica virgifera virgifera, or Western Corn Rootworms (WCR), the model species of BISEM, is a maize specialist and is able to detoxify the degradation product of benzoxazinoids, the (MBOA). This lipophilic compound is toxic to most insect herbivores, but WCR is able to convert it to MBOA-Glc, by adding a glucose molecule and stabilizing it to a hydrophilic compound. MBOA-Glc has been shown to be present in the cuticle and feces of these larvae and it is repellent to the major enemy of WCR, entomopathogenic nematodes. The main objective of this project was to investigate the impact of benzoxazinoids on the biology of the WCR, one of the major pests of maize crops that sequesters benzoxazinoids from maize root. Through molecular manipulation, we investigated the impact of these secondary metabolites in this sequestering root pest.
During its term, the BISEM project established a protocol to silence D. virgifera genes using dsRNA and artificial diet and developed first insights into the potential role of different candidate genes in MBOA-Glc formation by. D. virgifera. Detoxification genes, such as UGTs, are ubiquitous in all organisms, and are important in many physiological processes, not just metabolization of specialized plant metabolites. With the organization and annotation of the UGTs in D. virgifera, it opened other possibilities of understanding the importance of this group of genes in the biological and ecological aspects of the larvae.
Sustainable agriculture is one of the hot subjects in the field of plant and insect interactions, due to the necessity of protecting crops from pests without harming the environment and human health. The results obtained from BISEM are an important step to understand the main pest of maize crops in the Northern Hemisphere, and consequently provide foundation for crop protection strategies. Strategies such as silencing key genes through dsRNA is already a widespread strategy to counter pests, and silencing genes that are involved in sequestration of chemical protection against their enemies could be a promising method in the future.