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Population dynamics and pathogens of the western bean cutworm (Striacosta albicosta)
Title
Population dynamics and pathogens of the western bean cutworm (Striacosta albicosta)
Creator
Bunn, Dakota C.
Date
2022
Description
Understanding an herbivorous pest’s population dynamics is necessary to ensure proper integrated pest management strategies are being...
Show moreUnderstanding an herbivorous pest’s population dynamics is necessary to ensure proper integrated pest management strategies are being developed and used. The western bean cutworm is a pest of both corn and dry beans that is understudied and difficult to manage due to its nocturnal lifestyle, adaptation to current management techniques and a general lack of understanding regarding its population structure. Our studies focused on the effects of host plant and pathogens on western bean cutworm population structure and found that mainly adults which developed on corn are contributing to the next generation of western bean cutworm in Michigan, making corn and dry beans unsuitable as co-refuges in insecticide resistance management strategies.We also found a 100% prevalence of the Nosema sp. in the adult population of western bean cutworm in Michigan. This prevalence, when paired with the consistent crop damage caused annually by the western bean cutworm, which confirms an abundance of cutworms are present, suggests the infection is slow acting and non-lethal to its host. Following sequencing, assembly, and annotation of the Nosema sp. genome, we were unable to provide a reason for the Nosema sp.’s low virulence, however, we were able to confirm the presence of all 6 polar tube proteins. Upon further examination of the Nosema sp. genome we were able to determine that it is a true Nosema with genome size of ~9.57 Mbp (~20% of which are transposable elements), which is within the typical range for this genus.
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Evolution and adaptations to host plants in the beetle genus Diabrotica
Title
Evolution and adaptations to host plants in the beetle genus Diabrotica
Creator
Lata, Dimpal
Date
2022
Description
Corn rootworms (Diabrotica spp.) are among the most destructive pests impacting agriculture in the U.S and are an emerging model for insect...
Show moreCorn rootworms (Diabrotica spp.) are among the most destructive pests impacting agriculture in the U.S and are an emerging model for insect-plant interactions. We have a limited understanding of the genome-scale level difference between specialist and generalist corn rootworm species and their interaction with their host plants. Genome sizesof several species in the genus Diabrotica and an outgroup were estimated using flow cytometry. Results indicated that there has been a recent expansion in genome size in the common ancestor of the virgifera group leading to Diabrotica barberi, Diabrotica virgifera virgifera, and Diabrotica virgifera zeae. Comparative genomic studies between the fucata and virgifera groups of Diabrotica revealed that repeat elements, mostly miniature inverted-transposable elements (MITEs) and gypsy-like long terminal repeat (LTR) retroelements, contributed to genome size expansion. The initial transcriptional profile in western corn rootworm neonates when fed on different potential host plants demonstrated a strong association between western corn rootworm and maize, which was very distinct from other possible hosts and non-host plants. The results also showed presence of several larval development related transcripts unique to host plants and the presence of several muscle development and stress response related transcripts unique to non-host plants. The effect of the maize defensive metabolite DIMBOA on corn rootworms was studied using a novel plant-free system. The survival of both southern and western corn rootworms was not affected at a low concentration of DIMBOA. However, the concentration above the physiological dose found in plants affected the survival of corn rootworms. DIMBOA had no plant independent effect on these corn rootworms weight gain.
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