Pest Management Science (2021) 77, 5375-5381

Acácio Gonçalves Netto, Erick M.G. Cordeiro, Marcelo Nicolai, Saul J.P. de Carvalho, Ramiro Fernando Lopez Ovejero, Caio A.C.G. Brunharo, Maria I. Zucchi and Pedro J. Christoffoleti (2021)
Population genomics of Digitaria insularis from soybean areas in Brazil
Pest Management Science 77 (12), 5375-5381
Abstract:
BACKGROUND
Digitaria insularis is a weed species that has gained considerable importance in Brazil's soybean production areas that rely on glyphosate-resistant cultivars. Herbicide-resistant weed populations of this species have been reported in many regions in Brazil, first in the south, followed by later reports in the north. We hypothesized that the spread of herbicide-resistant D. insularis is facilitated by movement of agricultural machinery from the southern regions of Brazil.
RESULTS
Population genomics revealed a weak or no genetic structure (F_ST = [0; 0.16]), moderate expected heterozygosity (H_E = 0.15; 0.44) and low inbreeding (F_IS = [-0.1; 0.1]) in D. insularis populations. Our data supported the hypothesis that herbicide resistance gene flow predominantly occurred in a south-to-north direction based on a migration analysis. We also found evidence of local adaptation of resistant populations in the northern soybean-growing regions of Brazil.
CONCLUSION
Evidence in our work suggests that gene flow of glyphosate-resistant D. insularis is associated with movement of agricultural machinery, although local selection pressure seems to play an important role in the evolution of herbicide resistance throughout the country. Our results suggest preventive practices such as equipment sanitation should be implemented to limit the spread of herbicide resistant D. insularis.
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Full text of article
Database assignments for author(s): Pedro Jacob Christoffoleti

Research topic(s) for pests/diseases/weeds:
pesticide resistance of pest

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Digitaria insularis (weed)	Soybean (Glycine max)	Brazil (south)
	Digitaria insularis (weed)	Soybean (Glycine max)	Brazil (NW)
	Digitaria insularis (weed)	Soybean (Glycine max)	Brazil (NE)