Ecological Entomology (2018) 43, 332-341

Keith A. Hobson, Kyle Doward, Kevin J. Kardynal and Jeremy N. McNeil (2018)
Inferring origins of migrating insects using isoscapes: a case study using the true armyworm, Mythimna unipuncta, in North America
Ecological Entomology 43 (3), 332-341
Abstract: 1. Many important insect pests undertake seasonal migrations at continental scales in response to changes in resource quality and availability. The frequency and timing of these events could be influenced by the impact of climate change on the suitability of the different sites exploited throughout the year, yet, in many cases, little is known about the origin of seasonal populations, as tracking insect movements is extremely challenging due to their small body size.
2. The use of stable isotope measurements in insect tissues combined with the development of tissue-specific 'isoscapes' of modelled geographic isotope patterns presents a potentially valuable but rarely used approach for obtaining such information on important pest species. In this paper it is illustrated how stable hydrogen isotope analyses (δ²H) in wing chitin of the true armyworm (Mythimna (Pseudaletia) unipuncta Haworth), a seasonal migrant, clearly delineated between 2016 spring immigrants and later locally produced moths in southern Ontario, Canada.
3. It is shown that adult moths captured in early fall in Texas were immigrants from farther north, the first direct confirmation of a southward return migration of this species. Stable carbon isotope (δ¹³C) measurements indicated that spring immigrants in Ontario and autumn immigrants in Texas were from exclusively C3 biomes. Stable nitrogen isotope (δ¹⁵N) measurements also provided information on the probability of individuals coming from agriculturally intensive (i.e. higher δ¹⁵N) sites. Finally, several recommendations are provided regarding future research that could improve the Bayesian assignment models and thus improve assignment accuracy.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Jeremy N. McNeil

Research topic(s) for pests/diseases/weeds:
population dynamics/ epidemiology

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Mythimna unipuncta		Canada (east)
	Mythimna unipuncta		U.S.A. (mid S)