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Master of Science




Vojislava Grbic


The two-spotted spider mite Tetranychus urticae is a polyphagous agricultural pest of economic importance. Previous studies have established that reduced gene expression of COPB2, SNAP-α, and V-ATPase genes with RNAi and lowers both the survivorship and fecundity of T. urticae. A visible phenotype was also associated with changes to the digestive cells of the midgut after treatment. Serial sections of paraffin embedded RNAi treated mites to determine the changes caused by the transcriptional silencing of the three focal genes. COPB2 silencing leads to a significant increase in the number of juvenile digestive cells, while SNAP-α and V-ATPase silencing caused dysfunctional mature digestive cells. The formation and disruption of these digestive cells may provide a potential tool in integrated pest management.

Summary for Lay Audience

The spider mite Tetranychus urticae is a global pest. Previous studies found that the downregulation of the vesicular trafficking genes COPB2, SNAP-α and V-ATPase resulted in a morphological change, that negatively affected the longevity and reproductive output of T. urticae. This study tries to identify changes in terms of what is changing inside the spider mite after genetically silencing these genes with RNA interference. The data suggest RNA interference of these vesicular trafficking genes will cause abnormalities in the life cycle of digestive cells that are found within the midgut of T. urticae. RNA interference of COPB2 causes an increase in the number of digestive cells and increases the proportion of younger digestive cells compared to older digestive cells. The silencing of other similar vesicular trafficking genes produces similar results. The changes caused by RNA interference may not be localized to one gene but to the system they are part of.

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Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

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