Demographic histories of three predatory lady beetles reveal complex patterns of diversity and population size change in the United States

Arun Sethuraman, Fredric J. Janzen, Michael A. Rubio, Yumary Vasquez, John J. Obrycki

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Predatory lady beetles (Coccinellidae) contribute to biological control of agricultural pests, however, multiple species frequently compete for similar resources in the same environment. Numerous studies have examined ecological interactions among the native North American convergent lady beetle (Hippodamia convergens) and two introduced species, the seven-spotted lady beetle (Coccinella septempunctata) and the Asian lady beetle (Harmonia axyridis), in agricultural fields and described multiyear population dynamics. However, the evolutionary dynamics of these interacting species of predatory beetles are uncharacterized. We utilize publicly available multilocus genotype data from geographically disjunct populations of these three species to estimate demography across North American populations. Coalescent analyses reveal (1) a recent (∼4–5 years) decline (>12 fold) in microsatellite effective population size of H. convergens, while expanding (mutation scaled growth rate in 1/u generations = 2910, SD = 362) over evolutionary time scales, (2) a massive (>150 fold), and very recent, effective population size decline in Ha. axyridis, and (3) population size growth (mutation scaled growth rate = 997, SD = 60) over recent and evolutionary time scales in C. septempunctata. Although these estimates are based on genetic data with different mutation rates and patterns of inheritance (mitochondrial versus nuclear), these dynamic and differing population size histories are striking. Further studies of the interactions of these predatory lady beetles in the field are thus warranted to explore the consequences of population size change and biological control activities for evolutionary trajectories in North America.

Original languageEnglish
Pages (from-to)1065-1079
Number of pages15
JournalInsect Science
Issue number6
StatePublished - Dec 2018

Bibliographical note

Publisher Copyright:
© 2017 Institute of Zoology, Chinese Academy of Sciences


  • biological control
  • bottleneck
  • demography
  • effective population size
  • invasiveness
  • predatory lady beetles

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Agronomy and Crop Science
  • General Biochemistry, Genetics and Molecular Biology
  • Insect Science


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