Journal of Economic Entomology (2021) 114, 1173-1179

K. Harrington, Y. Carrière and A.M. Mostafa (2021)
Re-evaluating the economic injury level for alfalfa weevil (Coleoptera: Curculionidae) control in low desert irrigated alfalfa
Journal of Economic Entomology 114 (3), 1173-1179
Abstract: Alfalfa (Medicago sativa L.) dominates cropping systems in the Western United States and is first in terms of acreage planted in Arizona. The alfalfa weevil, Hypera postica (Gylenhall) and/or Hypera brunneipennis (Boheman), respectively, is the most destructive pest in terms of yield loss in low desert-grown alfalfa hay. The current economic threshold of 15–20 larvae per sweep, established in California in 1975, is currently not suitable or adopted by growers in the western U.S. low desert. Here, we conducted 4 yr of field trials to re-evaluate this economic threshold. Supporting observations of agricultural growers and professionals in the region, our results indicate that the economic threshold established in 1975 is too high. Specifically, one to three large larvae often cause a significant decrease in yield justifying weevil control based on current hay prices and costs of insecticide application. These results are discussed in the context of sustainable alfalfa production in the western U.S. low desert.
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Full text of article
Database assignments for author(s): Yves Carriere

Research topic(s) for pests/diseases/weeds:
control - general
thresholds/decision-support systems

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Hypera postica	Alfalfa/lucerne (Medicago sativa)	U.S.A. (SW)