The effects of development and chronic oxidative stress on telomere length in an agricultural pest moth, Helicoverpa armigera
Telomeres are repetitive sequences located at the end of chromosomes in eukaryotes that protect against loss of important sequences during the cell replication process. Telomere length (TL) shortens with every round of cell division. When a telomere becomes too short, cells can no longer proliferate and this triggers the cell apoptosis process. Apart from cell replication, the length of telomeres can be affected by factors such as sex, genetics, and stress levels. Oxidative stress in particular can cause damage to telomeres and telomere maintenance processes, resulting in TL shortening. This phenomenon occurs in humans and many vertebrates, especially endothermic species. However, the ways in which various stress types affect the TL of invertebrate species remains ambiguous. Here, we examined the effects of development and oxidative stress on TL in the invertebrate pest moth, Helicoverpa armigera. In the former case, we extracted genomic DNA from three developmental stages (1-day old egg, 4th instar, and first-day emerged moths) and measured TL by qPCR. In the latter, we chronically exposed individuals to paraquat - an organic herbicide that induces oxidative stress - and then measured TL as per our development methodology. In addition, we examined TL in a subset of published whole genome short-read sequencing data of caterpillars and moths using the software, Computel. In our experimental work, we found that TL in H. armigera was significantly longer at the early stages of development and shortens in later stages. However, oxidative stress does not appear to shorten TL in H. armigera following chronic exposure to paraquat. In our Computel analysis, we found that caterpillars had longer mean TL than moths but this difference was not significant due to the high variation among samples. Collectively, our research provides new data on TL in an underrepresented group, adding new insights into the progression of TL shortening with development and the effects of oxidative stress on TL, while also more generally highlighting the value of applying complementary approaches to TL measurement.