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Item Can conservation biocontrol of wheat stem sawfly be improved? Contributions of supplemental nutrition to longevity, egg load, and egg volume of Bracon cephi and B. lissogaster(Montana State University - Bozeman, College of Agriculture, 2022) Cavallini, Laissa; Chairperson, Graduate Committee: David K. Weaver; This is a manuscript style paper that includes co-authored chapters.Wheat stem sawfly (WSS), Cephus cinctus, is a major pest of wheat, causing losses that exceed $350 million annually across the Northern Great Plains. Two native parasitoids, Bracon cephi and B. lissogaster, suppress C. cinctus populations in wheat fields, where the immatures feed on and kill C. cinctus larvae. The success of natural enemies is linked to access to supplemental food in the field, which increases their life span and benefits their reproductive parameters. To assess the benefits that supplemental nutrition might have on B. cephi and B. lissogaster, we reared adult females on carbohydrate-rich diets combined with and without amino acids, with water and water plus amino acids as controls. We also conducted greenhouse experiments with the non-native, warm-season cover crop cowpea, Vigna unguiculata, as an extrafloral nectar source for parasitoids. Cages containing individual females were placed on living plants enclosing either cowpea inflorescence stalk extrafloral nectar (IS-EFN) or the leaf stipel extrafloral nectar (LS-EFN), with a supply of water as the negative control and buckwheat nectar as the positive control. In both lab and greenhouse experiments, females were observed daily to assess longevity, while egg load and volume were assessed 2, 5, and 10 days after placement. Results show that both species increased longevity when provided carbohydrate-rich food. B. cephi enhanced egg load and volume with carbohydrate-rich diets, and the addition of amino acids tending to benefit these parameters. Results show that IS-EFN increases longevity in both parasitoids. B. lissogaster kept constant egg load and volume, while B. cephi increased reproductive parameters with IS-EFN. These native braconid parasitoids are unfamiliar with non- native cowpea plants. Hence, we tested their attraction to cowpea volatiles, where positive responses were observed. Our results show that supplemental nutrition greatly benefits B. cephi and B. lissogaster females, with cowpea IS-EFN improving their longevity and reproductive parameters. Therefore, we suggest that cowpea has potential to be considered as a food supplement crop in conservation biocontrol programs to reduce WSS populations.Item Population dynamics of wheat stem sawfly, Cephus cinctus Norton, in barley in Montana(Montana State University - Bozeman, College of Agriculture, 2020) Achhami, Buddhi Bahadur; Chairperson, Graduate Committee: David K. Weaver; Gadi V. P. Reddy, Jamie D. Sherman, Robert K. D. Peterson and David K. Weaver were co-authors of the article, 'Antixenosis, antibiosis, and potential yield compensatory responses in barley cultivars exposed to wheat stem sawfly under field conditions' which is contained within this dissertation.; Gadi V. P. Reddy, Jamie D. Sherman, Robert K. D. Peterson and David K. Weaver were co-authors of the article, 'Effect of precipitation and temperature on larval survival of Cephus cinctus (Hymenoptera: Cephidae) in barley cultivars' which is contained within this dissertation.; Robert K. D. Peterson, Jamie D. Sherman, Gadi V. P. Reddy and David K. Weaver were co-authors of the article, 'Multiple decrement life tables of Cephus cinctus Norton (Hymenoptera: Cephidae) across a set of barley cultivars: the importance of plant defense versus cannibalism' which is contained within this dissertation.; Gadi V. P. Reddy, Megan L. Hofland, Robert K. D. Peterson, Jamie D. Sherman and David K. Weaver were co-authors of the article, 'Host selection and oviposition behaviors of Cephus cinctus (Hymenoptera: Cephidae) in barley' which is contained within this dissertation.Wheat stem sawfly (WSS) is an economically devastating pest of cereals grown in North America. The larva is the only feeding stage and remains confined within a host stem until it emerges as an adult the following year. This limited mobility increases larval vulnerability to mortality factors when host plant traits are hostile to survival. For instance, larval mortality is greater in barley than in solid stemmed wheat cultivars known to be resistant. Both solid stemmed wheat and barley kill neonates via host plant resistance traits. Traditionally, barley was recommended as an alternative rotational crop to prevent WSS outbreaks in wheat crops. There is limited data available regarding barley host plant resistance and questions persist. Has barley resistance changed over time? What is the impact of larval feeding injury on grain yield of barley? Do females display similar oviposition behaviors across barley cultivars that vary in susceptibility? To answer these questions. I conducted field experiments to assess resistance and possible tolerance to WSS in eight barley cultivars. Based on the number of eggs, 'Hockett' was the most attractive cultivar to WSS female (less antixenosis), while 'Craft' and 'Celebration' killed the greatest number of neonates due to antibiosis. Multiple decrement life table studies revealed that plant defense and cannibalism were two major causes of larval mortality. We measured greater yield in infested stems with dead larvae (potential tolerance) than for cut stems and both were greater than uninfested stems in all cultivars except 'Celebration'. A greenhouse study revealed that females preferred 'Hockett' over 'Craft' in frequencies of oviposition behaviors and numbers of eggs deposited. Additionally, a greater amount of the WSS attractant (Z)-3-hexenyl acetate was found in aerations from 'Hockett' plants than from 'Craft.' The amount of defensive compound linalool was greater in aerations from 'Craft' than from 'Hockett.' These results suggest that barley cultivars are equipped with varying levels of antibiosis, antixenosis, and tolerance traits against WSS. Thus, we can exploit these traits in the development of cultivars which can reduce WSS populations and decrease economic loss caused by this species.Item 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.Item Evaluation of wheat production practices under wheat streak mosaic disease risk and wheat stem sawfly pressure in Montana(Montana State University - Bozeman, College of Agriculture, 2020) McKelvy, Uta; Chairperson, Graduate Committee: Mary Burrows; Monica Brelsford, Jamie Sherman and Mary Burrows were co-authors of the article, 'Susceptibility and tolerance of winter wheat, spring wheat and barley cultivars to mechanical inoculation with wheat streak mosaic virus' submitted to the journal 'Plant health progress' which is contained within this dissertation.; Peggy Lamb, Monica Brelsford and Mary Burrows were co-authors of the article, 'Impact of planting date, seeding rate and cultivar choice on spring and winter wheat productivity and profitability in Montana' submitted to the journal 'Agronomy journal' which is contained within this dissertation.; David Weaver and Mary Burrows were co-authors of the article, 'Evaluation of chemical and cultural management practices for wheat stem sawfly control and effects on beneficial insects in spring wheat in Montana' submitted to the journal 'Journal of economic entomology' which is contained within this dissertation.Wheat (Triticum aestivum L.) is an economically important crop for Montana's agricultural industry. Wheat streak mosaic (WSM) is an important viral disease in Montana and the wheat stem sawfly (WSS; Cephus cinctus Norton) is a major insect pest in the state. Understanding these disease and pest problems and the factors that promote and suppress disease and pest pressure forms the foundation for a successful integrated pest management program. In this dissertation, we evaluate wheat production practices in Montana and provide information on the effectiveness and implications of cultural and chemical management practices in mitigating WSM disease and WSS pressure. We assessed the tolerance of popular winter wheat, spring wheat, and barley cultivars in Montana to mechanical inoculation with WSMV in field studies. Winter wheat 'Brawl CL Plus' and breeding lines CO12D922 and MTV1681 demonstrated moderate WSMV incidence and minor yield penalties under WSMV inoculation, making them suitable cultivars to be grown in high-risk environments. We investigated the effects of cultivar choice, planting date, and seeding rate on grain yield and quality parameters in field studies. Our results validated current planting date recommendations for Montana. Yield reductions were observed at planting dates later than mid-September and April for winter wheat and spring wheat, respectively. No yield increase was observed when winter wheat was planted before mid-September. No meaningful and reliable economic benefits were associated with an increase in seeding rate beyond the recommended density. We developed a WSM risk prediction model and released it as the online learning tool AWaRe ('Assessment of Wheat streak mosaic Risk'). AWaRe presents the first learning tool that integrates complex information on the dynamics underlying WSM disease and relates them to the user in an interactive way. We expect the adoption of risk assessment based WSM management practices that result in a reduced economic impact through the use of this tool. The potential of different insecticides to manage WSS damage was compared to spring wheat genotypes with varying degrees of WSS resistance. Results showed that application of the systemic insecticide Thimet-20G provided effective protection of susceptible cultivar 'Reeder,' but use of solid-stem cultivars were similarly effective.Item 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. WeaverWheat 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.Item Impacts of dryland farming systems on biodiversity, plant-insect interactions, and ecosystem services(Montana State University - Bozeman, College of Agriculture, 2018) Adhikari, Subodh; Chairperson, Graduate Committee: Fabian D. Menalled; Laura Burkle (co-chair)Farming system impacts the structure and functioning of associated biodiversity and plant-insect interactions. However, the extent of these impacts is largely unknown in drylands of the Northern Great Plains, an important region for cereal, pulse, oilseed, and forage production. Using three complementary studies, I compared the impacts of conventional and organic systems on associated biodiversity (weeds, bees, insect pests, and parasitoids), bee-flower networks, and bumblebee colony success. First, I assessed stem cuts by and parasitism on Cephus cinctus (wheat stem sawfly) in spring and winter wheat cultivars grown in conventional and organic fields. I found that organic fields had less C. cinctus infestation and more braconid parasitoids of C. cinctus, indicating an increased pest regulation in organic system. I compared C. cinctus preference and survival on Kamut with Gunnison and Reeder wheat cultivars and found the lowest C. cinctus oviposition and survival in Kamut, suggesting that Kamut is a potential genetic source for this pest. Second, I assessed the impacts of conventional and organic systems on forb and bee communities. I found greater forb diversity and more connected bee-flower networks in organic fields, but bee communities did not differ between systems. Comprising only 12% of the landscape, natural habitat did not affect small-bodied bees in either system but had a positive effect on large-bodied bees at the scale of 2000 m radius. These results indicate that an increased forb diversity and bee-flower interaction in organic fields is not enough to offset the negative effects of landscape homogeneity on bees. Third, I compared Bombus impatiens colony success, worker condition, and colony-collected pollen between farming systems. I found greater growth rate, brood cells, and pollen species richness in B. impatiens colonies as well as lower wing wear and greater body lipid mass in workers from organic fields, than in conventional fields. The greater colony success and better worker conditions could be a proxy for better ecosystem services provided by organic fields. Overall, my studies show that organic farming supports greater associated biodiversity, more complex bee-flower networks, and better biodiversity-based ecosystem services in the Northern Great Plains.Item The potential of sugar resources in the reproductive biology of wheat stem sawfly parasitoids(Montana State University - Bozeman, College of Agriculture, 2018) dos Reis, Dayane Andrade; Chairperson, Graduate Committee: David K. Weaver; Robert K. D. Peterson, Megan L. Hofland and David K. Weaver were co-authors of the article, 'Differences in longevity, egg load, and egg volume due to sucrose feeding in two sympatric congeneric braconids that are specialist parasitoids of the wheat stem sawfly ' which is contained within this thesis.; Robert K. D. Peterson, Megan L. Hofland and David K. Weaver were co-authors of the article, 'The effect of cultivated and native floral species as resources in the reproductive biology of wheat stem sawfly parasitoids' which is contained within this thesis.The wheat stem sawfly, Cephus cinctus, is the most destructive insect pest of wheat, Triticum aestivum, in the Northern Great Plains of North America. Biological control by Bracon cephi and Bracon lissogaster is an important tool for integrated pest management of this pest, but parasitism rates are difficult to predict. Therefore, the main objective of this research was to characterize aspects of the reproductive biology of both parasitoid species to provide information that could enhance their effectiveness in biological control of C. cinctus. First, we investigated the role of diapause and the effects of sucrose feeding on reproduction of females. For that, we provided sucrose solution to overwintering and summer generation adult females, and we quantified and compared their longevity, egg load and egg volume. Our results showed no differences between overwintering and summer individuals of B. cephi and B. lissogaster. In contrast, sucrose feeding, increased longevity and egg load of both species and generations. The egg load of B. cephi was surprisingly low compared to B. lissogaster. However, only B. cephi increased egg volume when sucrose was provided. Our findings highlighted the contrasting life histories of both species, and showed the potential of sugar resources in enhancing their reproductive capacity. Subsequently, we investigated the effect of flower nectar on the same, above mentioned, reproductive traits of parasitoids. We chose buckwheat (Fagopyrum esculentum), lacy phacelia (Phacelia tanacetifolia), deerhorn clarkia (Clarkia pulchella), canola (Brassica napus), and safflower (Carthamus tinctorius) based on their occurrence as native plants, use in pollinator enhancement, and occurrence in rotational or cover crop plantings in Montana. We found that only B. cephi females benefitted from these flowering plants. The longevity and egg volume of females increased with buckwheat, and egg volume increased with both buckwheat and the native species, deerhorn clarkia. The strong effect of buckwheat on reproduction of B. cephi females suggests that flowers with similar nectar quality might have similar impacts. This information will be of great importance for selection of suitable flower species to enhance reproductive capacity of parasitoids through habitat management. Collectively, this research showed that there is potential to enhance effectiveness of parasitoids with sugar supplementation.Item Insect microbe interactions: honey bee antiviral defense mechanisms and characterization of Spiroplasma colonizing wheat stem sawfly(Montana State University - Bozeman, College of Agriculture, 2017) Brutscher, Laura Marie; Chairperson, Graduate Committee: Michelle Flenniken; Katie F. Daughenbaugh and Michelle L. Flenniken were co-authors of the article, 'Virus and DSRNA-triggered transcriptional responses reveal key components of honey bee antiviral defense' in the journal 'Scientific reports' which is contained within this thesis.; Curtis Fowler, David K. Weaver and Carl J. Yeoman were co-authors of the article, 'Identification and characterization of a Spiroplasma sp. (Ixodetis clade) associated with the wheat stem sawfly (Cephus cinctus)' submitted to the journal 'Microbial ecology' which is contained within this thesis.Insects play important roles in ecosystems throughout the world. There are many beneficial insects, including those that pollinate plants in diverse landscapes, while other insects are considered agricultural pests. Regardless of ecological role, insects are hosts for microbial symbionts and pathogens. Some microorganisms (e.g., viruses) are harmful to insect health, but many microbial symbionts aid in host biological processes. The projects herein describe the interplay between insects and microbes; specifically (1) honey bee host - virus interactions and (2) identification and characterization of a wheat stem sawfly-associated Spiroplasma. Honey bees (Apis mellifera) are pollinators of numerous agricultural crops and other plant species. Since 2006, there have been high annual losses of honey bee colonies in the U.S. (~33%) and throughout the world. Colony deaths are influenced by multiple factors including RNA virus infections. Honey bee antiviral defense involves several immune pathways, including dsRNA mediated responses, (i.e., RNA interference and non-sequence-specific dsRNA-triggered responses), but their relative importance in antiviral defense is not well understood. To investigate honey bee antiviral defense, bees were infected with model virus in the absence or presence of dsRNA, which reduced virus abundance. Transcriptome-level analysis determined hundreds of genes were differentially expressed in response to co-treatment of dsRNA and virus, including immune-related genes. RNAi-mediated gene knockdown of two putative antiviral genes increased virus abundance and supported their antiviral role. Additional investigation of these and other genes will improve our understanding of dsRNA-mediated antiviral defense in honey bees. In contrast, wheat stem sawflies (Cephus cintus) are major wheat pests in the Northwest United States. Strategies that target endosymbionts of sawflies could reduce wheat crop losses. Hereunto, the microbes that colonize wheat stem sawfly have not been explored. Targeted DNA sequencing determined sawflies were colonized by a Spiroplasma species that has greatest 16S rRNA sequence identity with Ixodetis clade species. Metagenomic sequencing identified several Spiroplasma encoded genes involved in metabolism, which may be important to the sawfly host. Further characterization of honey bee-virus interactions and the role of Spiroplasma in sawfly health may contribute to limiting threats to global crop production and will further scientific understanding of non-model insect-microbe interactions.Item Genetic basis of wheat resistance to the wheat stem sawfly(Montana State University - Bozeman, College of Agriculture, 2016) Varella, Andrea Correa; Chairperson, Graduate Committee: Luther E. Talbert; Luther E. Talbert, Robert K. D. Peterson, Jamie D. Sherman, Nancy K. Blake, Megan L. Hofland, John M. Martin and David K. Weaver were co-authors of the article, 'Host plant quantitative trait loci affect specific behavioral sequences in oviposition by a stem-mining insect' submitted to the journal 'BMC plant biology' which is contained within this thesis. [SUBMITTED]; Megan L. Hofland, Micaela Buteler, Luther E. Talbert, Jamie D. Sherman, Nancy K. Blake, Hwa-Young Heo, John M. Martin and David K. Weaver were co-authors of the article, 'Temporal patterns of pith expression and retraction in wheat stems and its effect on resistance to the wheat stem sawfly' submitted to the journal ' ' which is contained within this thesis. [SUBMITTED] [NO MAG]; David K. Weaver, Jamie D. Sherman, Nancy K. Blake, Hwa-Young Heo, Jay Kalous, Shiaoman Chao, Megan L. Hofland, John M. Martin, Kenneth D. Kephart and Luther E. Talbert were co-authors of the article, 'Association analysis of stem solidness and wheat stem sawfly resistance in a panel of North American spring wheat germplasm' submitted to the journal 'Crop sciences' which is contained within this thesis. [PUBLISHED]The wheat stem sawfly, Cephus cinctus Norton (WSS), has been a serious pest of wheat in the Northern Great Plains of North America for decades. Host plant resistance has been most consistently effective and is the foundation for integrated pest management of the WSS; therefore, the main objective of this research was to enhance the repertoire of genetic resistance to WSS available for exploitation by wheat breeders through marker-assisted selection (MAS). We used two strategies to achieve our goal. First, we better characterized resistance provided by previously identified quantitative trait loci (QTL). For that, we developed populations of near-isogenic lines (NILs) polymorphic for resistance QTLs on chromosomes 2D (Qwss.msub-2D), 3B (Qss-msub-3BL) and 4A (Qwss.msub-4A.1). Near-isogenic lines were tested greenhouse cage trials and in the field at both WSS-infested and uninfested locations. The Qwss.msub-4A.1 was shown to affect host plant attractiveness to foraging females, but did not change oviposition preference after females landed on the wheat stem. The Qwss.msub-2D and Qss-msub-3BL where shown to be associated with decreased preference for oviposition. The Qss-msub-3BL was also shown to be associated with temporal patterns of stem solidness expression, with the allele derived from the spring wheat cultivar Conan providing decreased infestation, high neonatal mortality, high levels of early stem solidness, and a rapid rate of pith retraction during stem maturation. Together, these studies characterized the effect of each one of these QTLs on WSS resistance. This information will help wheat breeders and entomologists to better integrate management strategies to reduce damage caused by the WSS. Our second strategy, involved the identification of new marker-trait associations for WSS resistance. For that, we used a panel of 244 elite spring wheat lines from North America. By conducting an association mapping study we were able to identify several QTLs for WSS resistance, including QTLs for early and late stem solidness, heading date, stem cutting, and larval mortality. This study showed that improvements in WSS management may be obtained using alleles that already exist in elite germplasm. Collectively, our research provided wheat breeders with a better tool kit for improving resistance to the WSS.Item Discovery and characterization of olfactory-related genes in the wheat stem sawfly, Cephus cinctus, a major pest of wheat in the northern plains(Montana State University - Bozeman, College of Agriculture, 2014) Gress, Joanna Christine; Chairperson, Graduate Committee: Kevin Wanner; Hugh M. Robertson, David K. Weaver, Mensur Dlakic and Kevin W. Wanner were co-authors of the article, 'Odorant receptors of a primitive hymenopteran pest, the wheat stem sawfly' in the journal 'Insect molecular biology' which is contained within this thesis.; Hugh M. Robertson, Kim Walden and Kevin. W. Wanner were co-authors of the article, 'Olfactory-related genes annotated from the wheat stem sawfly, cephus cinctus' submitted to the journal 'Insect molecular biology' which is contained within this thesis.; Hugh M. Robertson, Kim Walden and Kevin W. Wanner were co-authors of the article, 'Annotation of the major chemosensory gene families in the wheat stem sawfly, Cephus cinctus, a major pest of wheat in the northern plains' submitted to the journal 'Insect molecular biology' which is contained within this thesis.; Charles C. Carey, Aurélien Mazurie and Kevin W. Wanner were co-authors of the article, 'Antennal expression of candidate olfactory-realted genes from the wheat stem sawfly, Cephus cinctus' submitted to the journal 'Insect molecular biology' which is contained within this thesis.The wheat stem sawfly (WSS), Cephus cinctus (Hymenoptera: Cephidae), is one of the most important insect pests of wheat in the northern Great Plains region of the United States and Canada, with economic losses exceeding $100 million per year. Traditional pest management strategies including pesticides are generally unsuccessful due to an extended adult flight time and the inaccessible larval stage that feeds within the wheat stem. Research towards integrated pest management strategies based on olfaction has proved promising. However, little is known about the molecular basis of olfaction in this important insect pest. We have identified and annotated 131 members of the major olfactory-related gene families from antennal transcriptome and whole genome sequences, including: 6 odorant binding proteins (OBP), 8 chemosensory proteins (CSP), 53 odorant receptors (OR), 14 ionotropic receptors (IR), 12 carboxylesterases (CCE), 8 gluthatione S-transferases (GST), and 29 cytochrome P450s (P450). Expression levels in the antennae, sawfly bodies, and whole larvae were analyzed using RNA-seq. Gene expression results were used to identify candidate genes for further functional characterization based on higher enriched expression in antennae and/or sex-biased expression in the antennae. These candidate WSS olfactory genes may mediate important pest behaviors and serve as molecular targets for future insect management strategies.