Causes of variation in female host plant preference in the butterfly Pieris napi
Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
Herbivorous insects are a highly diverse group of organisms, with much of the diversification in the group seemingly related to resource specialization in relation to their host plants. Most herbivorous insects are host specialists, meaning that females oviposit and larvae feed on a limited number of plant species. Theoretically, females would be favoured by ovipositing on the plants on which their larvae fare the best, but in many cases female host plant preference does not match larval performance. This might be due to genetic, physiological and ecological factors. In this study I perform a suite of experiments on green-veined white butterflies (Pieris napi) from a single population to investigate genetic and environmental impacts on female host plant preference and larval performance. Results suggest that host plant preference is under genetic control, likely by genes on the X-chromosome, and that the physiological state and size of the adult butterfly may further affect oviposition behaviour. In contrast, experience from the larval stage had no effect on adult host plant preference. Additionally, there was no strong correlation between female preference and larval performance, and a substantial proportion of females oviposited also on a plant species which was unsuitable for their larvae to feed on. This indicates that genes controlling preference and performance are not linked to each other. Interestingly, the individual females that were reluctant to oviposit on the unsuitable host plant also avoided another perfectly suitable host plant, suggesting that females laying more eggs on the latter, suitable host also to a higher degree mistakenly oviposited on the unsuitable host. Hence, a contributing factor explaining why female preference and larval performance are not correlated might be limits in information processing for the butterflies, if neurological limitations constrain the ability of females to make optimal host plant choices. Studies on such limitations, along with an increased understanding of the genetic architecture of preference and performance could help explain why the vast majority of herbivorous insects are host plant specialists.
Place, publisher, year, edition, pages
2016. , 32 p.
IdentifiersURN: urn:nbn:se:uu:diva-274540OAI: oai:DiVA.org:uu-274540DiVA: diva2:896861
Master Programme in Biology