Scholarly Work - Land Resources & Environmental Sciences
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/8680
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Item Dietary sugars and amino acids increase longevity and enhance reproductive parameters of Bracon cephi and B. lissogaster , two parasitoids that specialise on wheat stem sawfly(Wiley, 2023) Cavallini, Laissa; Peterson, Robert K. D.; Weaver, David K.The wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae), is a major pest of wheat grown on the Northern Great Plains and Canadian Prairies of North America, causing economic losses of as much as $350 million annually. Two species that parasitize wheat stem sawfly larvae in wheat stems are Bracon cephi (Gahan) and B. lissogaster Muesebeck (Hymenoptera: Braconidae). Carbohydrate-rich diets increase adult parasitoid longevity and reproductive parameters, enhancing their success as natural enemies. In previous studies, these species had increased longevity, egg load, and volume when fed sucrose solutions, encouraging further research on their nutritional needs. Therefore, we conducted experiments with artificial diets using adult females fed sucrose, glucose, and fructose solutions. Females were also fed these sugars in combination with a mixture of amino acids. We assessed individuals daily for longevity. Both species benefited from diets containing carbohydrates, with an increase in longevity from an average of 9 to 51 days for B. cephi, and from 6 to 34 days for B. lissogaster. Additional experiments assessed egg load and volume after 2, 5, and 10 days of cumulative feeding in B. cephi. These females produced 1.4-fold more eggs when fed amino acids, 2.5-fold more with sugar, and 2.7-fold more when fed sugar with amino acids. They had a 1.3-fold increase in egg volume when fed amino acids, 1.9-fold with sugar, and 2.1-fold when fed sugar with amino acids. Our study reveals the nutritional requirements of these braconid parasitoids and the benefits of nutritional sources when implementing conservation biological control strategies.Item Stability analysis of stem solidness, grain yield, and grain protein concentration in spring wheat(Canadian Science Publishing, 2021-08) Subedi, Maya; Cárcamo, Héctor A.; Knodel, Janet J.; Weaver, David K.; Cuthbert, Richard D.; Pozniak, Curtis J.; Nilsen, Kirby T.; Beres, Brian L.The wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae), is a major pest of wheat (Triticum aestivum L.) in the northern Great Plains, where it is a constant threat in Montana and is resurging in Alberta, Saskatchewan, and North Dakota. Adoption of solid-stemmed cultivars is an important management tool for wheat growers; however, the inconsistent pith expression first noted with the release of ‘Rescue’ has been repeatedly observed in modern cultivars such as ‘Lillian’ in Canada. Given the extensive hectares planted to solid-stemmed wheat cultivars during an outbreak, the identification of cultivars that display stable stem solidness, grain yield, and grain protein concentration across a wide range of environments where stem sawfly infestations occur is desirable. We assessed spring wheat plant responses in eight solid-stemmed and two hollow-stemmed genotypes grown across diverse environments using multiple statistical models. Study sites included southern Alberta and Saskatchewan, Montana, and North Dakota. Most models agreed that the genotypes ‘Choteau’, ‘BW925’, and ‘Mott’ consistently displayed high and stable stem solidness concomitant with high grain yield. ‘Choteau’ and ‘BW925’ also consistently met or exceeded the desired threshold of a 3.75/5 pith rating (averaged from the lower four stem internodes) for optimum resistance, whereas ‘Mott’ developed optimal pith at a specific (early) phenological stage when resistance to wheat stem sawfly infestation is critical. Exploring the stability of stem solidness identified ideal genotypes that would enhance germplasm development efforts, which exemplifies how this approach can facilitate the selection, production, and adoption of solid-stemmed wheat cultivars in regions prone to wheat stem