Intraspecific Hybridization Improves Performance of the Biological Control Agent Hypena opulenta

Area of Science:

• Applied Ecology
• Genetics
• Biological Control

Background:

• Introduced species can lose genetic diversity through drift and selection, potentially hindering their effectiveness.
• Biological control agents often have low genetic diversity due to small founding populations and long-term rearing.
• Intraspecific hybridization may counteract diversity loss by increasing heterozygosity and improving performance.

Purpose of the Study:

• To evaluate if intraspecific hybridization can enhance genetic diversity and performance of Hypena opulenta, a biological control agent.
• To assess the impact of short-term isolation on genetic structure and heterozygosity in H. opulenta populations.
• To compare the performance of hybridized H. opulenta with source populations under laboratory and field conditions.

Main Methods:

• Whole Genome Sequencing (WGS) was used to analyze genetic divergence and heterozygosity in lab-reared and field-established H. opulenta populations.
• A third population was created by crossing individuals from the lab and field populations.
• Performance was compared across the three populations (lab, field, and hybridized) in both laboratory and field settings.

Main Results:

• Despite recent separation, distinct genetic structures were observed between lab and field populations, both showing low heterozygosity.
• The outbred (hybridized) population exhibited significantly higher genome-wide heterozygosity.
• Hybridization led to improved performance, including increased pupal production, greater host plant defoliation, and higher second-generation adult emergence in the field.

Conclusions:

• Even short-term isolation can cause significant genetic divergence in populations.
• Intentional intraspecific hybridization is a viable strategy to increase genetic diversity and enhance the performance of biological control agents.
• Outcrossing recently separated populations offers a practical method to improve biological control agent effectiveness before field release, with implications for conservation.