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Exploring the potential of entomopathogenic nematodes against wireworms in Montana
(Montana State University - Bozeman, College of Agriculture, 2020) Sandhi, Ramandeep Kaur; Chairperson, Graduate Committee: Michael A. Ivie; David Shapiro-Ilan, Anamika Sharma Gadi V P Reddy were co-authors of the article, 'Efficacy of available entomopathogenic nematode strains against Limonius californicus (Mannerheim)' in the journal 'Biological control' which is contained within this dissertation.; Ratnasri Pothula, Satyendra K. Pothula, Byron J. Adams, Gadi V.P. Reddy were co-authors of the article, 'First record of native entomopathogenic nematodes from Montana agroecosystems' in the journal 'Journal of nematology' which is contained within this dissertation.; David Shapiro-Ilan and Gadi V.P. Reddy were co-authors of the article, 'Montana native entomopathogenic nematode species against Limonius californicus (Coleoptera: Elateridae)' in the journal 'Journal of economic entomology' which is contained within this dissertation.; David Shapiro-Ilan, Gadi V P Reddy and Michael A. Ivie were co-authors of the article, 'Efficacy of entomopathogenic nematode infected insect cadavers against wireworms in greenhouse and field' submitted to the journal 'Pest management science' which is contained within this dissertation.; Gadi V P Reddy, David Shapiro-Ilan and Michael A. Ivie were co-authors of the article, 'Effect of soil texture, soil moisture, and soil temperature on efficacy of entomopathogenic nematode strains against wireworms under laboratory conditions' submitted to the journal 'Journal of applied entomology' which is contained within this dissertation.
Wireworms (Coleoptera: Elateridae), are important soil-dwelling pests and have become a serious threat to spring wheat in the Northern Great Plains because of lack of effective control measures, creating a need for alternative control methods such as biological control with entomopathogenic nematodes (EPNs). Ten EPN strains were tested against sugarbeet wireworm, Limonius californicus (Mannerheim) in laboratory bioassay. Out of these ten strains, Steinernema carpocapsae (Weiser) (All and Cxrd strains) and S. riobrave Cabanillas, Poinar, and Raulston (355 and 7-12 strains) were found effective in laboratory and shade house. However, the dose required to kill at least 50% of the treated L. californicus larvae was 200 infective juveniles/cm 2. Two Montana native EPN species (S. feltiae and Heterorhabditis bacteriophora) were extracted and were evaluated against L. californicus in laboratory and shade house. Although, 50% mortality was observed due to S. feltiae isolates in laboratory conditions, none of the two isolates of S. feltiae performed well against L. californicus in shade house. Steinernema carpocapsae and S. riobrave in the form of infected Galleria mellonella L. cadavers were evaluated against wireworms (L. californicus and H. bicolor) in field and greenhouse. In field, none of the four EPN strains were found effective in reducing wireworm populations or protecting crop yield in both spring wheat and barley fields. However, only one infected Galleria cadaver of S. carpocapsae (All and Cxrd) and S. riobrave 355 was able to kill wireworm larvae as well as reduce wheat plant damage in greenhouse. The imidacloprid treatment enhanced the infection and killing ability of EPNs against L. californicus. Steinernema carpocapsae All and Cxrd were able to kill 30-46% of L. californicus larvae in all four soil types tested as compared to S. riobrave 355 and 7-12 strains, when maintained at field capacity moisture levels. However, S. carpocapsae All and Cxrd strains were able to infect 35-50% wireworm larvae in sandy loam and clay loam soil type at standardized moisture (18%). Steinernema carpocapsae All and Cxrd killed greater wireworm numbers at 16% moisture level and 25 °C as compared to other moisture and temperature levels in sandy clay loam soil. These results indicate that EPN based strategies could be useful for wireworm management but need to be explored further under field conditions. This strategy can at least be part of a large Integrated Pest Management system for wireworm control in Montana.
Assessment of host selection behaviors and oviposition preferences of Cephus cinctus Norton (Hymenoptera: Cephidae) using wheat and smooth brome
(Montana State University - Bozeman, College of Agriculture, 2020) Bhandari, Rekha; Chairperson, Graduate Committee: David K. Weaver and Tracy M. Sterling (co-chair)
Wheat stem sawfly, Cephus cinctus Norton (WSS), is an important pest of cereal crops in Northern Great Plains. Smooth brome has historically been suggested as a potential trap crop around wheat fields in Montana. The objective of this study was to compare oviposition preference and selection behaviors of female WSS and measure subsequent larval survival in wheat and smooth brome stems. We compared infestation, parasitism and larval development of WSS using field transects in smooth brome and adjacent wheat fields. We found no clear difference in infestation between the two host plants. There was greater larval mortality and less tunneling in smooth brome stems compared to wheat at a site near Big Sandy, Montana. At a second site near Big Sandy, there was greater infestation in smooth brome compared to wheat, but there were more dead larvae and greater parasitism in smooth brome. In Y-tube olfactometer studies, WSS females were more attracted to volatiles emitted by smooth brome than wheat. In greenhouse trials, the observation of specific behaviors leading to oviposition indicated differences in duration of ovipositor insertion and in number of ovipositor insertions that favored greater oviposition in smooth brome, but only by emergence of the first awn of the inflorescence (Zadoks 49 growth stage). There were different numbers of eggs in smooth brome stems relative to wheat, with no difference in the proportion of infested stems in choice tests conducted for two days at Zadoks 49. In no-choice tests, there were differences in both infested stems and in the number of eggs in stems at Zadoks 49. We found significantly greater amounts of key behaviorally active compounds used by female WSS, like (Z)-3-hexenyl acetate and beta-ocimene, that were among the few differences in the amounts of volatile compounds collected from two plant species. The greater amount of these compounds leads to more eggs that subsequently experience greater larval mortality in young plants, resulting in fewer cut stems in mature plants. Our findings support the consideration of smooth brome for use in trap crops to improve integrated pest management strategies for WSS.
The effects of increasing crop diversity on populations of wheat stem sawfly (Cephus cinctus) and associated braconid parasitoids
(Montana State University - Bozeman, College of Agriculture, 2019) Fischer, Benjamin Vernon; Chairperson, Graduate Committee: David K. Weaver
Wheat stem sawfly, Cephus cinctus (Norton) (WSS) is the most damaging pest of wheat in the Northern Great Plains. Insecticides are not widely used to control this insect, and cultural control methods provide inconsistent management of this pest. However, biological control by the parasitoids Bracon cephi (Gahan) and Bracon lissogaster Muesebeck has been shown to reduce damage caused by WSS. In addition, increased agroecosystem diversity has benefitted biological control agents in many other systems. Therefore, this study assessed the effect on populations of WSS and associated parasitoids by the inclusion of pulse and cover crops near wheat fields. Field trapping, dissection of postharvest crop residue, and rearing of insects out of crop residue were used to survey WSS and parasitoid populations in pairs of wheat fields throughout the major wheat producing regions of Montana. One wheat field in each pair was seeded next to a fallow field, and the other was seeded next to a field of either pulse or cover crop. Postharvest stem dissection samples show that wheat fields next to pulse or cover crops had a mean increase of 51 parasitoids per m 2 than wheat fields next to fallow. A corresponding 3% reduction in stem cutting was also observed in postharvest samples from wheat fields adjacent to flowering pulse or cover crops. Land-use data from CropScape TM were used as well to evaluate other land-use impacts around each wheat field such as wheat, fallow, grassland/pasture, flowering crops, and developed space. The regression equation Y = 18.96X + 6.08, where X = proportion of fallow land within 2 km of the wheat field and Y = square root of WSS abundance in a 7.5 m sample of crop residue from rows of wheat, can be used to predict WSS abundance in wheat fields. Replacing fallow fields with flowering pulse or cover crops in the Northern Great Plains may be an important integrated pest management tactic to reduce WSS damage. Cultural practices such as crop diversification are key to developing consistent biological control for WSS.
Natural enemy abundance and biological control in Bt maize using simulations of predator-prey interactions
(Montana State University - Bozeman, College of Agriculture, 2017) Brown, Christopher Regan; Chairperson, Graduate Committee: Robert K. D. Peterson; Laura A. Burkle, Daniel Salinas Duron, Adam Schapaugh, Christopher K. Sehy, Paul C. Stoy, David K. Weaver, Jeffrey D. Wolt and Robert K. D. Peterson were co-authors of the article, 'Simulating interactions between natural enemies and pests in maize to assess the influence of alternative food, cannibalism, and intraguild predation' which is contained within this thesis.; Laura A. Burkle, Daniel Salinas Duron, Adam Schapaugh, Christopher K. Sehy, Paul C. Stoy, David K. Weaver, Jeffrey D. Wolt and Robert K. D. Peterson were co-authors of the article, 'Simulating interactions between natural enemies and prey in Bt and conventional maize' which is contained within this thesis.
The potential effects of genetically modified maize expressing insect-resistant proteins from Bacillus thuringiensis (Bt) on natural enemies represent an active area of research highlighting considerable interest in understanding even subtle perturbations in agroecosystems. In the case of Bt maize, indirect effects on natural enemies may occur due to a reduced prey base caused by the desired effect of pest control by the Bt plant. Although these indirect effects may be subtle and difficult to study in the field, a modeling approach offers an alternative, allowing factors related to these subtle effects to be easily explored. In this effort, simulations of interactions between maize, two pests (the European corn borer (ECB) and an aphid), and two natural enemies (a lady beetle and green lacewing) were made using a modified TrophicLink model. TrophicLink is an individual-based model that uses functional ecology and food web network theory to simulate the trophic interactions of individuals and the resulting flow of energy. The individual-based model approach emphasizes the unique experiences of individuals and their trophic interactions leading to system level effects. Pollen utilization, cannibalism, and intraguild predation by natural enemies were simulated to explore the influence of these factors and to test the model. The model performed well in terms of reasonable representation of trophic functional types and interactions between them. The natural enemies were able to reduce a lepidopteran pest population and partially protect yield. The presence of pollen was influential in natural enemy population sizes and the biological control they provide. Cannibalism and intraguild predation caused notable reductions in natural enemy populations, but only small differences in biological control levels. In a second set of simulations involving Bt maize, prey-reduced scenarios included a short-term Bt maize scenario with ECB eggs and young larvae, and a second scenario without any ECB representing regional suppression of ECB by wide adoption of the Bt maize. Lady beetle and green lacewing population mass were similar across scenarios indicating resiliency of the generalist natural enemies to prey removal in the scenarios simulated. These findings are consistent with field study data that have not found consistent effects of Bt maize on natural enemies.
Evaluation of trap crops for the management of wireworms in spring wheat in Montana
(Montana State University - Bozeman, College of Agriculture, 2017) Adhikari, Ashish; Chairperson, Graduate Committee: Gadi V. P. Reddy; Michael A. Ivie (co-chair); Gadi VP Reddy was a co-author of the article, 'Evaluation of trap crops for the management of wireworm in spring wheat in Montana' submitted to the journal 'Journal of economic entomology' which is contained within this thesis.
Wireworms, the larval stage of click beetles, have slender, shiny, hard bodies with three pairs of legs. They are polyphagous and have cryptic habitats. In recent years, increasing wireworm numbers and damage have become a major problem for growers in the Golden Triangle Region of Montana. The control of this pest is very difficult because after the removal of Lindane by US Environmental Protection Agency (USEPA) in 2009, the use of the second generation insecticides have not been able to provide effective control of wireworms. Thus, using insecticides to control wireworms has not been effective at high population levels. Also, little is known about the biology and feeding habit of wireworms. The goal of this study is to evaluate trap crops that can protect the spring wheat by attracting wireworms. First, field trials were conducted at two locations to investigate on the use of peas Pisum sativum L. (Fabaceae), lentils Lens culinaris L. (Fabaceae), canola/rapeseed Brassica napus L. (Brassicaceae), corn/maize Zea mays L. (Poaceae), durum Triticum durum Desf. (Poaceae) and barley Hordeum vulgare L. (Poaceae) as traps intercropped with spring wheat Triticum aestivum L. (Poaceae). The efficacy of trap cropping was determined by damage assessment in wheat plants along 1m transects and by counting wireworm populations on wheat and trap crop rows of a plot. Secondly, the effect of intercrop spacing on plant damage and the number of wireworms was determined for pea and lentil trap crops. To support field trials potted experiments were set up in the shade house to determine wireworm distributions in two-choice assays. Collectively the results from this study showed that pea and lentil trap crops resulted in significantly lower damage in wheat plants and they attracted more numbers of wireworms compared to other crops. Results from shade house trails supported observations from the field trials. An intercropping spacing of 0.5m between pea or lentil and the spring wheat crop produced highest density of spring wheat plants. The results from these experiments will add to the basic understanding of trap cropping for wireworms control.
Chemical control and disease reservoir studies of the wheat curl mite (Aceria tosichella Keifer), vector to wheat streak mosaic virus
(Montana State University - Bozeman, College of Agriculture, 2016) Murphy, Carmen Yvette; Chairperson, Graduate Committee: Mary Burrows
Wheat streak mosaic virus (WSMV) causes yield loss to wheat (Triticum aestivum) in all areas of the world where the crop is grown. No chemical controls for the WSMV vector, the wheat curl mite (WCM, Aceria tosichella Keifer), are approved. Control relies primarily on avoiding a 'green-bridge' of living plant material that can host the disease between seasons. This study aimed to 1) identify chemical treatments for WCM control under conventional and organic systems and clarify misconceptions that treatments, such as sulfur, control WCM and 2) analyze the capacity of 20 grassy species to serve as reservoirs of WSMV and WCM. The effects of insecticides with varying modes of action (carbamate, organophosphate, pyrethroid, neonicotinoid, biological control, oil, ovicide, mite growth inhibitor, and soap) on WCM population growth were tested in the greenhouse. Treatment with the active ingredients aldicarb and chlorpyrifos decreased WCM populations compared to untreated controls (p<0.001 and p<0.001). Field trials were conducted in spring wheat in 2013 and winter wheat in 2013-2014. Similar effects on WSMV spread were not observed in field trials. These trials included ten products consisting of five modes of action: organophosphates, pyrethroid, oil, soap and mite growth inhibitor. Chlorpyrifos was included in the field trials, but no efficacy was seen in 2013 compared to controls under good infection and incidence and infection was low in 2014, therefore we were unable to distinguish any treatment effect. To assess the capacity of 20 grassy species to serve as reservoirs of WSMV and WCM, plants with varying lifespan and origin were grown in the greenhouse and infested with viruliferous WCM. Lifespan had the greatest impact on ability of plants to host WCM (p=0.011) and WSMV (p<0.001). Annual plant species are more likely to host WCM than perennial grasses, with all species hosting WCM. Native and introduced species tested did not differ in ability to host WCM (p=0.735) and WSMV (p=0.096). This study provides evidence of potential for use of active ingredient chlorpyrifos in WCM control, and showed that lifespan is an important determinant of WSMV disease reservoir potential of grassy species.
The composition of wireworm species in Montana wheat and barley fields and its effect on developing IPM programs
(Montana State University - Bozeman, College of Agriculture, 2014) Morales-Rodriguez, Anuar; Chairperson, Graduate Committee: Kevin Wanner; Kevin W. Wanner was a co-author of the article, 'An evaluation of four different bait traps for sampling wireworms (Coleoptera: Elateridae) infesting cereal crops in Montana' submitted to the journal 'Journal of economic entomology' which is contained within this thesis.; Ruth P. O'Neill and Kevin W. Wanner were co-authors of the article, 'A survey of wireworm (Coleoptera: Elateridae) species infesting cereal crops in Montana' in the journal 'Pan-pacific entomologist' which is contained within this thesis.; Kevin W. Wanner was a co-author of the article, 'Determining the potential for cereal crop injury by wireworm species commonly found infesting cropland in Montana' submitted to the journal 'Canadian entomologist' which is contained within this thesis.; Kevin W. Wanner was a co-author of the article, 'Efficacy of thiamethoxam and fipronil, applied alone and in combination, to control Limonius californicus and Hypnoidus bicolor (Coleoptera: Elateridae)' in the journal 'Pest management science' which is contained within this thesis.; David Wichman and Kevin W. Wanner were co-authors of the article, 'Effects of cultural practices on wireworm populations and damage in cereal fields' submitted to the journal 'Crop sciences' which is contained within this thesis.
Wireworms, the larvae of click beetles, are the most important soil-insect pest of small grain fields in Montana. Worldwide, there are about 9,300 species of elaterids in 400 different genera, and in North America 885 species in 60 genera have been identified. In Montana, 166 species were identified, among them, 21 species have been identified as possible pests in small grain fields and some are serious pests of a wide variety of crops. My research focused on three main objectives related to wireworm IPM: first, the identification of the species causing damage in the field and their geographic and seasonal distribution in Montana; second, establishing the potential of different baited traps to monitor pest wireworm populations; and third, evaluating chemical and cultural management alternatives. To complete the first objective a statewide wireworm survey was conducted for three years as well as an intense sampling of four cereal fields season for three consecutive years. To complete the second objective, the effectiveness of four baited traps were assessed: traditional pitfall compared to pot, stocking and canister type traps, in four cereal fields for three years. To complete the last objective, laboratory, greenhouse and field studies were conducted to evaluate new insecticides, crop injury, tillage practices and seeding density. 5,097 wireworms were collected from the four sites during 2010 - 2012 including four common species, Aeolus mellillus, Hypnoidus bicolor, Limonius californicus and L. infuscatus, and three minor species, Agriotes spp., Dalopius spp. and Selatosomus aeripennis. Peak wireworm activity at the soil surface was found to coincide with cereal crop germination and establishment. While all trap types can be used to detect wireworm activity and estimate population levels, pitfall and stocking were more efficient than pot and canister traps. Thiamethoxam does not kill wireworms but its ability to suppress wireworm populations in the field can be improved by the addition of fipronil. Increasing seeding density is one of the most common cultural recommendations for managing wireworms, but my studies did not support its benefit to higher crop yields. Significantly, species-specific crop injury and seasonal movement in the soil support the need for species-specific IPM research.
Confirmation and management of glyphosate-resistant Kochia (Kochia scoparia) in Montana
(Montana State University - Bozeman, College of Agriculture, 2015) Kumar, Vipan; Chairperson, Graduate Committee: Prashant Jha; Prashant Jha and Nicholas Reichard were co-authors of the article, 'Occurrence and characterization of Kochia (Kochia scoparia) accessions with resistance to glyphosate in Montana' in the journal 'Weed technology journal' which is contained within this thesis.; Prashant Jha, Darci Giacomini, Eric Westra and Philip Westra were co-authors of the article, 'Molecular basis of evolved resistance to glyphosate and acetolactate synthase-inhibitor herbicides in Kochia (Kochia scoparia) accessions from Montana' submitted to the journal 'Weed science journal' which is contained within this thesis.; Prashant Jha was a co-author of the article, 'Impact of EPSPS gene amplification and intraspecific competition on fitness of glyphosate-resistan Kochia scoparia inbreds' submitted to the journal 'PLoS one journal' which is contained within this thesis.; Prashant Jha was a co-author of the article, 'Effective preemergence and postemergence herbicide programs for Kochia control' in the journal 'Weed technology journal' which is contained within this thesis.; Prashant Jha was a co-author of the article, 'Influence of herbicides applied postharvest in wheat stubble on control, fecundity, and progeny fitness of Kochia scoparia in the US Great Plains' in the journal 'Crop protection journal' which is contained within this thesis.; Prashant Jha was a co-author of the article, 'Influence of glyphosate timing on Kochia (Kochia scoparia) demographics in glyphosate-resistant sugar beet' submitted to the journal 'Weed technology journal' which is contained within this thesis.; Prashant Jha was a co-author of the article, 'Control of volunteer glyphosate-resistant canola in glyphosate-resistant sugar beet' in the journal 'Weed technology journal' which is contained within this thesis.
Kochia (Kochia scoparia L.) is one of the most problematic weeds in cropland and non-cropland areas of the US Great Plains. This research confirms the first report on glyphosate-resistant (GR) K. scoparia in Montana, and elucidates the mechanisms of glyphosate and ALS-inhibitor resistance, growth and reproductive fitness of GR K. scoparia, and its management. This research also reports the response of K. scoparia demographics to glyphosate timings in GR sugar beet and evaluate herbicide options for managing volunteer GR canola in GR sugar beet. Based on whole-plant dose-response experiments, four GR K. scoparia accessions (JOP01, GIL01, CHES01, CHES02) had 4.6 to 11-fold levels of resistance to glyphosate compared to a glyphosate-susceptible (GS) accession. Confirmed GR K. scoparia accessions (GIL01, JOP01, and CHES01) also exhibited 9.3- to 30-fold resistance to sulfonylurea herbicide (ALS inhibitors). Results from PCR, quantitative PCR, and immunoblotting assays indicated that EPSPS gene amplification (~ 4 to 10 copies) and single point mutation at Pro197 in ALS gene conferred resistance to glyphosate and ALS-inhibitors, respectively. Inbred lines of GR K. scoparia (CHES01 and JOP01) with 2- to 14-fold amplification of the EPSPS gene did not confer any growth- or fecundity-related fitness cost. From a management standpoint, acetochlor + atrazine, S-metolachlor + atrazine + mesotrione, and sulfentrazone applied PRE and paraquat + atrazine, paraquat + linuron, and paraquat + metribuzin applied POST or in postharvest wheat stubble provided effective (> or = 91%) control of K. scoparia. In GR sugar beet, sequential applications of glyphosate (6-leaf fb 10-leaf stage of sugar beet) reduced survival, biomass and seed production of K. scoparia plants in cohort 1 and 2; however, an additional application of glyphosate at the canopy closure stage of sugar beet was needed to prevent seed production from the late-emerging K. scoparia (cohort 3). Ethofumesate (4,200 g ha -1) PRE followed by sequential POST triflusulfuron methyl (17.5 g ha -1) was the most effective treatment for managing volunteer GR canola in GR sugar beet. Overall, this research demonstrates the adaptability of K. scoparia evolving resistance to glyphosate and ALS inhibitors, and suggest the need for adoption of integrated weed management practices.
Oviposition of the wheat stem sawfly (Cephus cinctus, Nort.) with special reference to some morphological characteristics of vulgare wheats
(Montana State University - Bozeman, College of Agriculture, 1955) Kreasky, Joseph B.
Inheritance of stem solidness and its relationship to yield and other agronomic traits in spring wheat
(Montana State University - Bozeman, College of Agriculture, 1993) Hayat, Mohammad Aslam
The wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae), a devastating pest of wheat, has caused considerable economic damage in the Pacific Northwest. Solid-stemmed wheat varieties have provided a genetic source of resistance against the insect. However, solid-stemmed wheats tend to yield less than hollow-stemmed wheats. Some, but not all, studies have shown yield to be negatively related to stem solidness. To date, it is not clear whether solid-stemmed wheats have low yield due to a negative genetic correlation or to the poor genetic background of the original solid-stemmed selections. The cause of the negative association between solid stems and other traits was studied in spring wheat using solid-stemmed wheats released in different eras. The progeny derived from different crosses between solid and hollow parents was evaluated to determine the genetic basis for improved yield in modern solid-stemmed spring wheats. Space-planted nurseries of different crosses grown in 1990 and 1991 showed that the genetic basis of stem solidness is different between an early release (Rescue) and a later release (Lew) Additionally, larger experiments of F6 progeny derived from crosses between solid and hollow parents were grown in two different environments and agronomic data were gathered. The genetic correlation coefficients between stem solidness and grain yield were small and did not tend to be negative. Therefore, no negative genetic relationship appears to exist between stem solidness and grain yield. However, stem solidness was found negatively correlated to protein and plant height in early solid-stemmed releases. Thus, it appears that a linkage existed between the genes for solid stems and genes conferring poor percent protein and tall plants in the early releases. This linkage appears to have been broken in later releases. Stem solidness was independent of all other traits studied. Heritabilities of all traits, except yield, were high.

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