Correlates of spread rates for introduced insects

Samuel Fahrner, Brian H. Aukema

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Aim: The rate at which introduced insects disperse into novel habitats is a key determinant of the impacts of biological invasions and the efficacy of importation biological control programs. Understanding which life-history traits or abiotic factors moderate spread rates is important for designing trapping and eradication programs for invasive insects and for designing release protocols of imported natural enemies. Our aim was to identify variables that can explain variation in spread rates of introduced insects. Location: Global. Spread rates from 30 different countries were compiled. Time period: 1976–2014. Major taxon studied: Insecta. Methods: We compiled 147 published spread rates of 86 non-native insects. Spread rates were averaged per species so that each insect was only represented once in statistical analyses. Simultaneously, we collected information on several variables associated with the introduced insects such as adult longevity, diet breadth, diet preference, eusociality, fecundity, taxonomic order, role of passive dispersal (important versus not important), size, type (invasive species versus biological control agent), voltinism (i.e., the number of generations per year) and duration of spread. In addition to analysis of the complete data set, analyses of several subsets of the data were conducted to determine robustness and sensitivity of findings. Results: In the global analysis, voltinism was clearly the most significant predictor of spread rates. Insects with more than one generation per year spread faster than those with one or fewer generations. Analyses limited to either invasive species or importation biological agents further confirmed that multivoltine insects spread faster on average than univoltine insects. Main conclusions: Whereas previous work has shown that accidentally introduced insects spread faster than those introduced intentionally, the identification of voltinism as a key predictor of spread may enhance risk analyses and accuracy of forecasting, especially where a changing climate may alter patterns of voltinism.

Original languageEnglish (US)
Pages (from-to)734-743
Number of pages10
JournalGlobal Ecology and Biogeography
Issue number6
StatePublished - Jun 2018

Bibliographical note

Funding Information:
College of Food, Agricultural, and Natural Resource Sciences at the University of Minnesota; McKnight Land-Grant Professorship; USDA Forest Service award 15-DG-1142004-237; University of Minnesota Doctoral Dissertation Fellowship

Funding Information:
We thank our global colleagues from the International Union of Forest Research Organizations meeting on invasive alien species and international trade in San Carlos de Bariloche, Argentina, for valuable discussions and feedback on an early version of this work in 2015, and faculty and students in the Department of Entomology at the University of Minnesota, Saint Paul, for valuable feedback as it was developed into a doctoral program seminar. This research was enabled by the work of graduate students, museum curators, and federal, state and university researchers, who have collected and published data on insect life histories and spread rates. Funding was provided by the College of Food, Agricultural and Natural Resource Sciences at the University of Minnesota, McKnight Land-Grant Professorship funds to BHA, USDA Forest Service award 15-DG-1142004-237, and a University of Minnesota Doctoral Dissertation Fellowship to SF. This manuscript was greatly improved by the insightful comments of two referees.

Publisher Copyright:
© 2018 John Wiley & Sons Ltd


  • dispersal
  • importation biological control
  • invasive
  • non-native
  • range expansion
  • voltinism


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