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Aphids In The Air: What Is The Risk For 2007?, Wayne Ohnesorg, Matthew E. O'Neal, Marlin E. Rice Dec 2006

Aphids In The Air: What Is The Risk For 2007?, Wayne Ohnesorg, Matthew E. O'Neal, Marlin E. Rice

Integrated Crop Management News

The 2006 growing season has come to a close and with it another year's worth of experience with the soybean aphid. For many, it was a quiet, "low aphid" year with few reports of economic outbreaks within Iowa. Reflecting these low populations in the field, we observed fewer aphids within our suction traps (Figure 1) compared to the 2005 growing season when the traps collected nearly 100 times more aphids (Figure 2). For the last two years, the Iowa suction trap network (Figure 3) has been part of a larger network of suction traps located in nine states throughout ...


High-Level Resistance To Bacillus Thuringiensis Toxin Cry1ac And Cadherin Genotype In Pink Bollworm, Aaron J. Gassmann, Robert W. Biggs, Jeffrey A. Fabrick, Bruce E. Tabashnick, Timothy J. Dennehy, Yves Carriere, Shai Morin Dec 2006

High-Level Resistance To Bacillus Thuringiensis Toxin Cry1ac And Cadherin Genotype In Pink Bollworm, Aaron J. Gassmann, Robert W. Biggs, Jeffrey A. Fabrick, Bruce E. Tabashnick, Timothy J. Dennehy, Yves Carriere, Shai Morin

Aaron J. Gassmann

Resistance to transgenic cotton, Gossypium hirsutum L., producing Bacillus thuringiensis (Bt) toxin Cry1Ac is linked with three recessive alleles of a cadherin gene in laboratory-selected strains of pink bollworm, Pectinophora gossypiella (Saunders), a major cotton pest. Here, we analyzed a strain (MOV97-R) with a high frequency of cadherin resistance alleles, a high frequency of resistance to 10 μg of Cry1Ac per milliliter of diet, and an intermediate frequency of resistance to 1,000 μg of Cry1Ac per ml of diet. We selected two strains for increased resistance by exposing larvae from MOV97-R to diet with 1,000 μg of Cry1Ac ...


Circadian Rhythms Of Feeding, Oviposition, And Emergence Of The Boll Weevil (Coleoptera: Curculionidae), Shoil M. Greenberg, J. S. Armstrong, Mamoudou Setamou, Thomas W. Sappington, Randy J. Coleman, Tong-Xian Liu Dec 2006

Circadian Rhythms Of Feeding, Oviposition, And Emergence Of The Boll Weevil (Coleoptera: Curculionidae), Shoil M. Greenberg, J. S. Armstrong, Mamoudou Setamou, Thomas W. Sappington, Randy J. Coleman, Tong-Xian Liu

Entomology Publications

Circadian rhythm of feeding, oviposition, and emergence of boll weevil adults were determined at five different photophases (24, 14, 12, 10, and 0 hours) and a constant 27°C temperature, 65% RH in the laboratory. Squares from Petri dishes, where they were exposed to boll weevil females, were removed and examined for feeding and oviposition punctures every 4 hours during daylight (0700–1900 h) and every 12 h at night (1900–0700 h) over eight consecutive days. Cohorts of randomly selected egg-punctured squares were sampled from ovipositing females at 0700, 1100, 1500, and 1900 during 24 hours and under different ...


Sampling European Corn Borer (Lepidoptera: Crambidae) Larvae From Seed Corn 1 Drying Bins For Bt Resistance Monitoring, Jarrad R. Prasifka, Douglas V. Sumerford, Richard L. Hellmich, Leslie C. Lewis, Dennis D. Calvin Dec 2006

Sampling European Corn Borer (Lepidoptera: Crambidae) Larvae From Seed Corn 1 Drying Bins For Bt Resistance Monitoring, Jarrad R. Prasifka, Douglas V. Sumerford, Richard L. Hellmich, Leslie C. Lewis, Dennis D. Calvin

Entomology Publications

Monitoring for resistance to Bacillus thuringiensis Berliner (Bt) toxins in transgenic crops is challenging, in part because alleles conferring resistance appear to be rare. Consequently, several complementary methods are used to identify, collect and test putatively resistant individuals. A series of experiments conducted at commercial seed production facilities explored an alternative sampling method. Larvae of the European corn borer, Ostrinia nubilalis Hübner, were collected from bins containing Bt hybrid seed corn and their inbred progeny (both F2 and backcross- F2 larvae) were tested for resistance to the Bt toxin Cry1Ab. Marked, laboratory-reared O. nubilalis larvae also were placed beneath drying ...


Impact Of Trap Design, Windbreaks, And Weather On Captures Of European Corn Borer (Lepidoptera: Crambidae) In Pheromone-Baited Traps, Brendon James Reardon, Douglas V. Sumerford, Thomas W. Sappington Dec 2006

Impact Of Trap Design, Windbreaks, And Weather On Captures Of European Corn Borer (Lepidoptera: Crambidae) In Pheromone-Baited Traps, Brendon James Reardon, Douglas V. Sumerford, Thomas W. Sappington

Entomology Publications

Pheromone-baited traps are often used in ecological studies of the European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae). However, differences in trap captures may be confounded by trap design, trap location relative to a windbreak, and changes in local weather. The objectives of this experiment were, first, to examine differences in O. nubilalis adult (moth) captures among the Intercept wing trap, the Intercept bucket/funnel UNI trap, and the Hartstack wire-mesh, 75-cm-diameter cone trap (large metal cone trap) as well as among three cone trap designs. Second, we examined the influence of the location of the large metal cone trap ...


Insect-Mediated Seed-Set Evaluation Of 21 Soybean Lines Segregating For Male Sterility At 10 Different Loci, E. Ortiz-Perez, Harry T. Horner, S. J. Hanlin, R. G. Palmer Dec 2006

Insect-Mediated Seed-Set Evaluation Of 21 Soybean Lines Segregating For Male Sterility At 10 Different Loci, E. Ortiz-Perez, Harry T. Horner, S. J. Hanlin, R. G. Palmer

Genetics, Development and Cell Biology Publications

The first requirement to establish a successful hybrid soybean program is the availability of a stable male-sterile, female-fertile system. Male sterility has been an important tool in soybean breeding programs to improve traits such as yield, seed-protein and seed-oil content, and seed size. However, improvement of seed-set per se on male-sterile plants has not been an important breeding objective. The evaluation of the out-crossing potential of the available male-sterile, female-fertile soybean lines is crucial to determine the future of hybrid soybean. The objective of this study was to evaluate seed-set among 21 soybean lines segregating for male sterility at 10 ...


Integrated Pest Management 101: Corn-Damaging Caterpillars, Marlin E. Rice Nov 2006

Integrated Pest Management 101: Corn-Damaging Caterpillars, Marlin E. Rice

Proceedings of the Integrated Crop Management Conference

One of the foundational elements of an integrated pest management program is correct identification of potential pest species. This presentation will provide participants an opportunity to test their identification skills in the arena of insect identification. The six most common caterpillar species (Order Lepidoptera) that attack mid- to late-vegetative stage or reproductive stage corn plants will be presented in a multiple-choice format. Circle the correct letter for each caterpillar photograph shown in the PowerPoint presentation. The key identifying characteristics for larvae in the mid to late instars are listed below for each of the correct species.


Western Bean Cutworm In Iowa, Illinois, Indiana And Now Ohio: Did Biotech Corn Influence The Spread Of This Pest?, Marlin E. Rice, David L. Dorhout Nov 2006

Western Bean Cutworm In Iowa, Illinois, Indiana And Now Ohio: Did Biotech Corn Influence The Spread Of This Pest?, Marlin E. Rice, David L. Dorhout

Proceedings of the Integrated Crop Management Conference

The western bean cutworm, Striacosta albicosta (Lepidoptera: Noctuidae), is native to North America. It was first reported as a pest of Colorado pinto beans in 1915. In 1935, adults were captured in western Nebraska (Hagen 1963) and later, in 1954, it was identified as a pest of corn in southern Idaho (Blickenstaff 1979). Since its discovery in the late 1880s, it has slowly and steadily expanded its known distribution eastward from Arizona to Iowa (Rice 2000) and Minnesota (O'Rourke and Hutchison 2000). The western bean cutworm was known to occasionally occur in western Iowa prior to 1975, but it ...


Rotation-Resistant Corn Rootworms 2006, Jon Tollefson, Patricia Prasifka, Benjamin Kaeb Nov 2006

Rotation-Resistant Corn Rootworms 2006, Jon Tollefson, Patricia Prasifka, Benjamin Kaeb

Proceedings of the Integrated Crop Management Conference

Corn rootworms have been, and in many cases still can be, managed with crop rotations. However, some populations of both northern and western corn rootworms (CRWs) have adapted to the com-soybean rotation. Regular, annual rotations between corn and soybeans have selected for a variant of the northern CRW that has a two-year life cycle, referred to as extended diapause. Female northern CRWs deposit eggs in the soil within cornfields. When the field is rotated to soybean the next year, most eggs hatch and the larvae starve. However, a portion of the eggs remain dormant in the soil for a second ...


Focus On Insects: Snapshots Of Newly Published Research In Agricultural Entomology, Marlin E. Rice Nov 2006

Focus On Insects: Snapshots Of Newly Published Research In Agricultural Entomology, Marlin E. Rice

Proceedings of the Integrated Crop Management Conference

The scientific literature contains a wealth of new information on insect biology, ecology, behavior and management, but seldom does this research directly reach the crop advisor or agri-business professional. During the last year, numerous research papers have been published that may have relevance to crop production and management in Iowa. Articles were selected from the scientific journals Environmental Entomology or journal of Economic Entomology. These journals are published bi-monthly with Environmental Entomology focusing on the interaction of insects with the biological, chemical, and physical aspects of their environment, while journal of Economic Entomology emphasizes articles on the economic significance of ...


Bt Rootworm Corn Failures: Understanding The Issues, Jon J. Tollefson, Marlin E. Rice Nov 2006

Bt Rootworm Corn Failures: Understanding The Issues, Jon J. Tollefson, Marlin E. Rice

Integrated Crop Management News

Genetically engineered corn that produces a Bt toxin effective against corn rootworms is now readily available and was widely planted in Iowa during 2006. Several seed companies have registrations, or will have shortly, and they will add additional Bt events and varieties to the choices for corn rootworm management. Does that mean that our corn rootworm management decisions are over, and we don't have to worry about rootworm injury? No. Bt corn rootworm hybrids are another insect management tool that must be thoughtfully incorporated into corn production practices.


Butterflies And Continuous Conservation Reserve Program Filter Strips: Landscape Considerations, Nicole M. Davros, Diane M. Debinski, Kathleen F. Reeder, William L. Hohman Nov 2006

Butterflies And Continuous Conservation Reserve Program Filter Strips: Landscape Considerations, Nicole M. Davros, Diane M. Debinski, Kathleen F. Reeder, William L. Hohman

Ecology, Evolution and Organismal Biology Publications

Filter strips or buffers are areas of grass or other perennial herbaceous vegetation established along waterways to remove contaminants and sediments from agricultural field runoff. In the heavily cultivated regions of the Midwestern United States, these buffer zones established under the Farm Bill provide important habitat for wildlife such as butterflies. The question of how the landscape context of these plantings influences their use has not been adequately researched. We used multiple regression and Akaike’s Information Criteria to determine how habitat width and several landscape-level factors (i.e., landscape composition [total herbaceous cover, amount of developed area, and amount ...


Reminder: Fall Pesticide Training, Keven Arrowsmith Oct 2006

Reminder: Fall Pesticide Training, Keven Arrowsmith

Integrated Crop Management News

Iowa State University's Extension Pest Management and the Environment program, in cooperation with the Iowa Department of Agriculture and Land Stewardship, provides continuing instructional courses (CIC) at sites across Iowa for certified commercial applicators. Obtain a registration form on the Web atwww.extension.iastate.edu/pme or visit your local county extension office.


Effects Of Living Mulches On Predator Abundance And Sentinel Prey In A Corn–Soybean–Forage Rotation, Jarrad R. Prasifka, Nicholas Schmidt, Keith A. Kohler, Matthew E. O'Neal, Richard L. Hellmich, Jeremy Singer Oct 2006

Effects Of Living Mulches On Predator Abundance And Sentinel Prey In A Corn–Soybean–Forage Rotation, Jarrad R. Prasifka, Nicholas Schmidt, Keith A. Kohler, Matthew E. O'Neal, Richard L. Hellmich, Jeremy Singer

Entomology Publications

Living mulches are cover crops grown concurrently within main crops for their benefits to weed control and soil quality. Because living mulches increase the diversity of vegetation in agricultural systems, they may impact the abundance or effectiveness of natural enemies. To examine the effects of living mulches on epigeal predators, arthropod abundance and feeding were examined in a rotation of corn (Zea mays L.), soybean (Glycine max L. Merr.), and forage crops in 2004 and 2005. Compared with a no-mulch control, the presence of alfalfa (Medicago sativa L.) and kura clover (Trifolium ambiguum M. Bieb.) mulches in corn and soybean ...


Dispersal Of Newly Eclosed European Corn Borer Adults (Lepidoptera: Crambidae) From Corn Into Small-Grain Aggregation Plots, Brendon James Reardon, Douglas V. Sumerford, Thomas W. Sappington Oct 2006

Dispersal Of Newly Eclosed European Corn Borer Adults (Lepidoptera: Crambidae) From Corn Into Small-Grain Aggregation Plots, Brendon James Reardon, Douglas V. Sumerford, Thomas W. Sappington

Entomology Publications

Genetically modified, insecticidal Bacillus thuringiensis (Bt) corn, Zea mays L., hybrids are used throughout the Corn Belt for European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), control. To slow development of Bt corn resistance, the Environmental Protection Agency requires growers to plant a refuge. Determining the appropriate distance between a refuge and Bt corn, and development of mitigation–remediation strategies such as mass releases of susceptible moths, requires an understanding of adult dispersal and mating behavior. However, much remains unknown about these behaviors. Because mating often occurs in grass near cornfields where adult O. nubilalis aggregate, we planted small-grain plots ...


Influence Of Elm Foliar Chemistry For The Host Suitability Of The Japanese Beetle, Popillia Japonica, And The Gypsy Moth, Lymantria Dispar, Gretchen Paluch, Fredric Miller, Junwei Zhu, Joel R. Coats Oct 2006

Influence Of Elm Foliar Chemistry For The Host Suitability Of The Japanese Beetle, Popillia Japonica, And The Gypsy Moth, Lymantria Dispar, Gretchen Paluch, Fredric Miller, Junwei Zhu, Joel R. Coats

Entomology Publications

The Asian elm trees that are closely associated with the David complex, Ulmus davidana (Planch), U. propinqua (Koidz), U. japonica (Rehd.), and U. wilsoniana (Schneid), show substantial levels of disease resistance and tolerance. Studies have shown that these species suffer moderate levels of injury from the adult Japanese beetle, Popillia japonica (Newman) (Coleoptera: Scarabaeidae). The research presented here reports the influence of elm leaf chemistry on the feeding activity of two generalist herbivores, the Japanese beetle and gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae). Elm leaf chemistry was surveyed for 19 species, 5 cultivars, and 2 varieties that are known ...


A Roller Coaster Season, Richard O. Pope Sep 2006

A Roller Coaster Season, Richard O. Pope

Integrated Crop Management News

Like most years for Iowa farmers, 2006 was a weather roller coaster ride. The graph shows the weekly departure from 30-year average degree day accumulations from May through September. One way to read the chart is to consider a 1- to 3-week time period and look at the slope of a line at that time. If it was warmer than normal, the line rises; if cooler than normal, the line falls; and if the weather is at the average, it will neither rise nor fall.


Adult Repellency And Larvicidal Activity Of Five Plant Essential Oils Against Mosquitoes, Junwei Zhu, Xiaopeng Zeng, Yanma, Ting Liu, Yuhua Han, Suqin Xue, Brad Tucker, Gretchen Schultz, Joel R. Coats, Wayne A. Rowley, Aijun Zhang Sep 2006

Adult Repellency And Larvicidal Activity Of Five Plant Essential Oils Against Mosquitoes, Junwei Zhu, Xiaopeng Zeng, Yanma, Ting Liu, Yuhua Han, Suqin Xue, Brad Tucker, Gretchen Schultz, Joel R. Coats, Wayne A. Rowley, Aijun Zhang

Entomology Publications

The larvicidal activity and repellency of 5 plant essential oils—thyme oil, catnip oil, amyris oil, eucalyptus oil, and cinnamon oil—were tested against 3 mosquito species: Aedes albopictus, Ae. aegypti, and Culex pipiens pallens. Larvicidal activity of these essentials oils was evaluated in the laboratory against 4th instars of each of the 3 mosquito species, and amyris oil demonstrated the greatest inhibitory effect with LC50 values in 24 h of 58 µg/ml (LC90  =  72 µg/ml) for Ae. aegypti, 78 µg/ml (LC90  =  130 µg/ml) for Ae. albopictus, and 77 µg/ml (LC90 ...


August Angst, Richard O. Pope Aug 2006

August Angst, Richard O. Pope

Integrated Crop Management News

August 2006 began where the rest of the season left off, warm and fairly dry. Sporadic thundershowers were the rule, with considerable local variation in rainfall. A storm system rolled through northwest and north-central Iowa, dropping 4 to 5 inches of rain in some areas. However, straight-line winds leveled corn and some soybeans in a narrow band from Plymouth to Dickinson County. Rain concerns continue in nearly all parts of Iowa. Aphid populations can be found in nearly all counties, but to date the only populations nearing threshold are located along the border with Minnesota.


Bean Pod Mottle Virus: Back With A Vengeance, John H. Hill, Palle Pedersen, Jeffrey D. Bradshaw Aug 2006

Bean Pod Mottle Virus: Back With A Vengeance, John H. Hill, Palle Pedersen, Jeffrey D. Bradshaw

Integrated Crop Management News

As stated in an earlier article in the ICM Newsletter (May 15, 2006), bean leaf beetles are back with a vengeance this year. Based on observations from agronomists across the state, this year seems to have the highest level of bean leaf beetles since 2002. This also has resulted in an apparent high incidence of bean pod mottle virus disease in Iowa fields. Infected plants can be characterized by the leaves, which show a yellow to green blotchy appearance called leaf mottle. Sometimes leaves have a raised or blistered appearance.


Using Genetic Markers And Population Assignment Techniques To Infer Origin Of Boll Weevils (Coleoptera: Curculionidae) Unexpectedly Captured Near An Eradication Zone In Mexico, Kyung Seok Kim, Pedro Cano-Rios, Thomas W. Sappington Aug 2006

Using Genetic Markers And Population Assignment Techniques To Infer Origin Of Boll Weevils (Coleoptera: Curculionidae) Unexpectedly Captured Near An Eradication Zone In Mexico, Kyung Seok Kim, Pedro Cano-Rios, Thomas W. Sappington

Entomology Publications

Several boll weevils, Anthonomus grandis Boheman, were captured in pheromone traps in 2004 near Tlahualilo, Durango, Mexico, an area where none had been reported for ≈10 yr. It is possible that they were from an endemic population normally too low in numbers to be detected but that increased in response to more favorable rainfall conditions in 2004. Alternatively, they may represent an influx of migrants or the immediate descendents of migrants. To identify the most likely origin of the boll weevils captured in this area, we characterized microsatellite variation of the Tlahualilo weevils and compared it with the variation from ...


Subacute Effects Of Cry1ab Bt Corn Litter On The Earthworm Eisenia Fetida And The Springtail Folsomia Candida, Bryan W. Clark, Joel R. Coats Aug 2006

Subacute Effects Of Cry1ab Bt Corn Litter On The Earthworm Eisenia Fetida And The Springtail Folsomia Candida, Bryan W. Clark, Joel R. Coats

Entomology Publications

Laboratory toxicity studies were conducted to determine the subacute effects of Bt Cry1Ab corn leaf material on nontarget soil organisms. Survival and growth were measured for an earthworm, Eisenia fetida Savigny, and survival and reproduction were measured for a springtail, Folsomia candida Willem. The organisms were provided leaf material of two Bt11 corn varieties, two Mon810 corn varieties, and the isolines of each, in a soil system and monitored for 28 d. An assay control treatment of an optimal food and a reference control treatment, using the herbicide pendimethalin, were used to provide a context for the observed results. Basic ...


The Heat (Has Been) On!, Richard O. Pope Jul 2006

The Heat (Has Been) On!, Richard O. Pope

Integrated Crop Management News

It should come as no surprise that the week of July 23 was a hot one in all of Iowa. We effectively gained an extra day and a half of heat compared with long-term averages in all parts of Iowa. Mind you that as corn and soybean are in the fill stage, degree days themselves aren't as important as they were in the leadup to pollination. Now we look at stresses on plants, and we do have variable moisture and accompanying heat stress in many parts of Iowa.


Spider Mites, Soybean Aphids, And Summer Temperature, Marlin E. Rice Jul 2006

Spider Mites, Soybean Aphids, And Summer Temperature, Marlin E. Rice

Integrated Crop Management News

Temperatures in the high 90s and low 100s have prompted questions about how this will affect pests in soybeans. Spider mites typically flourish in hot, dry weather. Fungal pathogens that suppress spider mites during high humidity and mild temperatures are less effective against mites during very dry and hot conditions. Therefore, spider mites may be a greater concern this year during early August than soybean aphids.


Location, Location, Location!, Richard O. Pope Jul 2006

Location, Location, Location!, Richard O. Pope

Integrated Crop Management News

The biggest factor determining the crop condition in late July is not a new one. If your location has caught some of the sporadic rainfall in the past month, you are likely in reasonable shape. If not, your crops are beginning to struggle. The driest areas in terms of rainfall deficit from normal since May 1 are northwest, west-central and south-central, which are all around 50 percent of normal rainfall. That said, corn and soybean both are hanging in pretty well, and late July and August rainfall will work wonders--if and when it comes.


Rotation-Resistant Corn Rootworms In Iowa, Patricia L. Prasifka, Jon J. Tollefson, Marlin E. Rice Jul 2006

Rotation-Resistant Corn Rootworms In Iowa, Patricia L. Prasifka, Jon J. Tollefson, Marlin E. Rice

Integrated Crop Management News

There are variants of both corn rootworm species in Iowa that are resistant to crop rotation. The northern corn rootworm overcame the annual rotation of corn with another crop by developing a two-year life cycle. This variety of the northern corn rootworm (known as extended diapause) became common and caused extensive damage to rotated corn in the late 1980s in northwest Iowa. Since then it has spread throughout Iowa and is probably found in every county.


These Are The Dog Days, Richard O. Pope Jul 2006

These Are The Dog Days, Richard O. Pope

Integrated Crop Management News

The traditional dog days of summer roughly range from July 4 through about August 10. Although they were named for the time when the dog star, Sirius, rose with the sun, dog days for us is the time when row crops are pollinating and the first half of grain fill. The week starting July 10 was about average in degree day accumulation, and especially in the southern two-thirds of Iowa, some welcome rain fell. Moisture remains a concern, but the week's rainfall coincided with pollination, which is a very good thing.


Protect Pollinating Bees From Pesticides, Chuck Eckermann, Joyce Hornstein Jul 2006

Protect Pollinating Bees From Pesticides, Chuck Eckermann, Joyce Hornstein

Integrated Crop Management News

A pesticide applicator is required to notify all owners of registered beeyards (apiaries) within a 2-mile radius of the site of application if the pesticide is labeled as "toxic to bees." Notification is required at least 24 hours and no more than 72 hours before the application. This enables beekeepers to move or otherwise protect their bees from harm. This notification is required by the Iowa Administrative Code rule IAC 21-45.31(206).


Mite Watch 2006, Carol Pilcher, Richard O. Pope Jul 2006

Mite Watch 2006, Carol Pilcher, Richard O. Pope

Integrated Crop Management News

Whenever hot, dry weather persists, spider mite populations may develop on both corn and soybean. Twospotted spider mites, Tetranychus urticae, are serious pests of many crops throughout the United States. Producers in areas of Iowa where the weather remains dry should be on the lookout for spider mite infestations.


July Picks Up Where June Left Off, Richard O. Pope Jul 2006

July Picks Up Where June Left Off, Richard O. Pope

Integrated Crop Management News

The first week of July was slightly cooler than normal statewide, and again, unfortunately, drier than normal. Corn is starting to tassel across Iowa, and moisture stress is a growing concern. Fortunately, crop breeding has provided us with varieties with improved drought tolerance; however, that only works to a point. Monitoring for pests is important, and grasshoppers and spider mites are two key insects to watch for.