Genome size evolution in the beetle genus Diabrotica.

Area of Science:

• Genomics
• Insect Biology
• Evolutionary Biology

Background:

• Diabrotica (Diabrocite) corn rootworms are major maize pests in the US and Europe.
• These insects are increasingly used as models for studying insect-plant interactions.
• Understanding their genome size is crucial for evolutionary and pest management studies.

Purpose of the Study:

• To estimate and compare the genome sizes of several Diabrotica species.
• To identify the genomic factors contributing to observed genome size variations.
• To investigate the evolutionary history of genome size in Diabrotica.

Main Methods:

• Flow cytometry was used to estimate genome sizes.
• Genome sequencing reads from Diabrotica subgroups were analyzed.
• Acalymma vittatum was used as an outgroup for phylogenetic comparison.

Main Results:

• Genome sizes for Diabrotica subgroups fucata and virgifera ranged from 1.56–1.64 Gb and 2.26–2.59 Gb, respectively.
• Acalymma vittatum had a genome size of approximately 1.65 Gb.
• The significant increase in genome size in the virgifera group ancestor was linked to a higher abundance of transposable elements, including miniature inverted-transposable elements and gypsy-like long terminal repeat retroelements.

Conclusions:

• Genome size expansion in the Diabrotica virgifera group ancestor is primarily driven by transposable elements.
• These findings provide insights into the genomic basis of pest evolution and diversification.
• Comparative genomics can elucidate the evolutionary dynamics of economically important insect pests.