Population genetic structure of an invasive forensically important insect

Area of Science:

• Forensic entomology
• Population genetics
• Molecular biology

Background:

• Insect population structure influences forensic utility.
• Limited data exists for introduced species' genetic diversity and differentiation.
• Chrysomya megacephala, an Asian fly, has been present in the continental USA since the 1980s.

Purpose of the Study:

• To characterize the population structure of the introduced fly, Chrysomya megacephala, in the continental USA.
• To assess its genetic diversity and geographic differentiation.
• To evaluate its potential forensic utility compared to native species.

Main Methods:

• Amplified Fragment Length Polymorphism (AFLP) profiling of adult Chrysomya megacephala.
• Analysis of Molecular Variance (AMOVA) to assess genetic variation.
• STRUCTURE and principal coordinate analyses for population clustering.
• Calculation of relative relatedness coefficients.

Main Results:

• Significant but very small genetic variation was found among samples across Florida and Alabama.
• Two distinct genetic clusters were identified, suggesting introduction from two separate source populations.
• Lower genetic diversity was observed in introduced Florida C. megacephala compared to native species and Malaysian C. megacephala.
• Genetic assignment for inferring corpse postmortem relocation was less successful for C. megacephala.

Conclusions:

• Introduced Chrysomya megacephala in Florida exhibits low genetic diversity and admixture, likely due to its introduction history.
• The population structure and reduced genetic diversity of C. megacephala may limit its reliability in forensic applications, particularly for postmortem relocation.
• Further research is needed to understand the long-term genetic consequences of introduction and refine forensic methodologies for non-native species.