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Iowa State University

Soybean

Entomology

Entomology Publications

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Management Of Insecticide-Resistant Soybean Aphids In The Upper Midwest Of The United States, Robert L. Koch, Erin W. Hodgson, Janet J. Knodel, Adam J. Varenhorst, Bruce D. Potter Jan 2018

Management Of Insecticide-Resistant Soybean Aphids In The Upper Midwest Of The United States, Robert L. Koch, Erin W. Hodgson, Janet J. Knodel, Adam J. Varenhorst, Bruce D. Potter

Entomology Publications

Since the first observation of soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), in North America in 2000, it has become the most economically damaging insect of soybean in the Upper Midwest of the United States. For the last 17 yr, soybean aphid management has relied almost entirely on the use of foliar-applied broad-spectrum insecticides. However, in 2015 in Minnesota, failures of foliar-applied pyrethroid insecticides were reported and pyrethroid resistance was confirmed with laboratory bioassays using lambda-cyhalothrin and bifenthrin. In 2016 and 2017, further reports of failures of pyrethroid insecticides and/or laboratory confirmation of resistance occurred in Iowa, North Dakota ...


Reduced Fitness Of Virulent Aphis Glycines (Hemiptera: Aphididae) Biotypes May Influence The Longevity Of Resistance Genes In Soybean, Adam J. Varenhorst, Michael T. Mccarville, Matthew E. O'Neal Sep 2015

Reduced Fitness Of Virulent Aphis Glycines (Hemiptera: Aphididae) Biotypes May Influence The Longevity Of Resistance Genes In Soybean, Adam J. Varenhorst, Michael T. Mccarville, Matthew E. O'Neal

Entomology Publications

Sustainable use of insect resistance in crops require insect resistance management plans that may include a refuge to limit the spread of virulence to this resistance. However, without a loss of fitness associated with virulence, a refuge may not prevent virulence from becoming fixed within a population of parthenogenetically reproducing insects like aphids. Aphid-resistance in soybeans (i.e., Rag genes) prevent outbreaks of soybean aphid (Aphis glycines), yet four biotypes defined by their capacity to survive on aphid-resistant soybeans (e.g., biotype-2 survives on Rag1 soybean) are found in North America. Although fitness costs are reported for biotype-3 on aphid ...


Survey Of Soybean Insect Pollinators: Community Identification And Sampling Method Analysis, K. A. Gill, M. E. O'Neal Jun 2015

Survey Of Soybean Insect Pollinators: Community Identification And Sampling Method Analysis, K. A. Gill, M. E. O'Neal

Entomology Publications

Soybean, Glycine max (L.) Merrill, flowers can be a source of nectar and pollen for honey bees, Apis mellifera L. (Hymenoptera: Apidae), wild social and solitary bees (Hymenoptera: Apoidea), and flower-visiting flies (Diptera). Our objectives were to describe the pollinator community in soybean fields, determine which sampling method is most appropriate for characterizing their abundance and diversity, and gain insight into which pollinator taxa may contact soybean pollen. We compared modified pan traps (i.e., bee bowls), yellow sticky traps, and sweep nets for trapping pollinators in Iowa soybean fields when soybeans were blooming (i.e., reproductive stages R1–R6 ...


Aboveground Feeding By Soybean Aphid, Aphis Glycines, Affects Soybean Cyst Nematode, Heterodera Glycines, Reproduction Belowground, Michael T. Mccarville, David H. Soh, Gregory L. Tylka, Matthew E. O'Neal Jan 2014

Aboveground Feeding By Soybean Aphid, Aphis Glycines, Affects Soybean Cyst Nematode, Heterodera Glycines, Reproduction Belowground, Michael T. Mccarville, David H. Soh, Gregory L. Tylka, Matthew E. O'Neal

Entomology Publications

Heterodera glycines is a cyst nematode that causes significant lost soybean yield in the U.S. Recent studies observed the aphid Aphis glycines and H. glycines interacting via their shared host, soybean, Glycine max. A greenhouse experiment was conducted to discern the effect ofA. glycines feeding on H. glycines reproduction. An H. glycines-susceptible cultivar, Kenwood 94, and a resistant cultivar, Dekalb 27–52, were grown in H. glycines-infested soil for 30 and 60 d. Ten days after planting, plants were infested with either zero, five, or ten aphids. At 30 and 60 d, the number of H ...


Effects Of Rag1 On The Preference And Performance Of Soybean Defoliators, Robert F. Bruner, Erin W. Hodgson, Aaron J. Gassmann Dec 2013

Effects Of Rag1 On The Preference And Performance Of Soybean Defoliators, Robert F. Bruner, Erin W. Hodgson, Aaron J. Gassmann

Entomology Publications

The Rag1 gene confers antibiotic resistance to soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), and in 2010, varieties expressing Rag1 were released for commercial use in the United States. We do not know how Rag1 varieties will influence the broader community of defoliating insects that inhabit soybean fields. In 2010 and 2011, the preference and performance of pest insects that defoliate soybeans [Glycines max (L.) Merr] were tested using Rag1 and aphidsusceptible varieties. Three coleopterans and four lepidopterans were used: northern corn rootworm, Diabrotica barberi Smith & Lawrence (Coleoptera: Chrysomelidae); southern corn rootworm, Diabrotica undecimpunctata howardi Barber (Coleoptera: Chrysomelidae); bean leaf beetle, Ceratoma trifurcata ...


Measuring The Benefit Of Biological Control For Single Gene And Pyramided Host Plant Resistance For Aphis Glycines (Hemiptera: Aphididae) Management, Michael T. Mccarville, Matthew E. O'Neal Oct 2012

Measuring The Benefit Of Biological Control For Single Gene And Pyramided Host Plant Resistance For Aphis Glycines (Hemiptera: Aphididae) Management, Michael T. Mccarville, Matthew E. O'Neal

Entomology Publications

The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is an economically important pest in the north central United States. In the state of Iowa, economically damaging populations occurred in seven of 11 growing seasons from 2001 to 2011. The high frequency and economic impact of the soybean aphid makes it an ideal candidate for management by using host plant resistance. We compared an aphid-susceptible line to near-isolines that contain Rag1 and Rag2, both alone and pyramided together, to suppress aphid populations and protect yield. Each of four near-isolines, were artificially infested with aphids and grown in small plots in which ...


Soybean Aphid (Hemiptera: Aphididae) Development On Soybean With Rag1 Alone, Rag2 Alone, And Both Genes Combined, Shaylyn Lena Wiarda, Walter R. Fehr, Matthew E. O'Neal Jan 2012

Soybean Aphid (Hemiptera: Aphididae) Development On Soybean With Rag1 Alone, Rag2 Alone, And Both Genes Combined, Shaylyn Lena Wiarda, Walter R. Fehr, Matthew E. O'Neal

Entomology Publications

Aphis glycines Matsumura (Hemiptera: Aphididae) can reduce the yield of aphidsusceptible soybean (Glycine max (L.) Merrill) cultivars. The Rag1 and Rag2 genes confer resistance to some biotypes of A. glycines. These genes individually can limit population growth of A. glycines and prevent yield loss. The impact of these genes when combined is not known. We compared the development of A. glycines on soybean with Rag1 alone (R1/S2), Rag2 alone (S1/R2), both genes combined (R1/R2), or neither gene (S1/S2). In addition, we determined the impact of different levels of aphid infestation on seed yield. The genotypes were ...


What Is The Economic Threshold Of Soybean Aphids (Hemiptera: Aphididae) In Enemy-Free Space?, Michael T. Mccarville, Charles Kanobe, Gustavo C. Macintosh, Matthew E. O'Neal Jan 2011

What Is The Economic Threshold Of Soybean Aphids (Hemiptera: Aphididae) In Enemy-Free Space?, Michael T. Mccarville, Charles Kanobe, Gustavo C. Macintosh, Matthew E. O'Neal

Entomology Publications

Soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is a serious pest of soybean, Glycine max (L.) Merr., in the North Central United States. Current management recommendations rely on the application of insecticides based on an economic threshold (ET) of 250 aphids per plant. Natural enemies are important in slowing the increase of aphid populations and can prevent them from reaching levels that can cause economic losses. However, biological control of A. glycines is inconsistent and can be affected negatively by the intensity of agricultural activity. We measured the impact of a natural-enemy-free environment on the capacity of the current ET ...