Does Insulin Regulate the pre migratory phenotype Diapause in Monarch Butterflies?
Lobert, Grant M.
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In fall months, monarch butterflies (Danaus plexippus) enter a phenotypic state called diapause that is characterized by the sequestration of fat reserves and halted development of reproductive organs . Diapause prepares monarchs for migration by changing their physiology in ways that are better suited for long distance flight. This state in invertebrates such as C. elegans and C. pipiens (nematodes and mosquitos) has been shown to be regulated by the insulin signaling pathway. Using dsiRNA (RNA interference), the genes for the insulin receptor InR , FOXO (Forkhead Transcription Factor) were targeted to test if this relationship exists in monarchs as well. Ideally mature oocytes would be counted for each treatment group for quantitative analysis. Due to an insufficient feeding protocol, quantitative data for this relationship was impossible to collect as the monarchs did not fully mature reproductively. However, photographs of the abdominal dissections reveal a potential success for future trials of this experiment with proper recalibration of the feeding protocol. It can be noticed in these photographs that the single individual with mature oocytes was in the FOXO RNAi treatment. This is consistent with the expectation for a role of insulin signaling in controlling diapause in monarchs.