Date of Completion

Spring 5-1-2024

Thesis Advisor(s)

Jessica Malek

Honors Major

Allied Health Sciences

Disciplines

Agriculture | Biodiversity | Biosecurity | Dietetics and Clinical Nutrition | Ecology and Evolutionary Biology | Entomology | Environmental Health | Environmental Public Health | Food Science | Life Sciences | Nutrition | Public Health

Abstract

Pollinator populations have seen massive declines over the past decade due to anthropogenic activity and climate change posing serious threats to the health of humans and ecosystems (Ulyshen & Horn, 2023). As agents responsible for the production of about 35% of micronutrient rich food crops necessary for adequate nutrition to lead healthful lives and prevent nutrition associated diseases, pollinator decline is a public health concern (Aizen et al., 2009). Monarch butterflies (Danaus plexippus) serve as bio indicators for the health of pollinator populations because of their analogous habitat and food resources shared with many other pollinator species, including bees and moths (Ghazanfar et al., 2016). Monarch decline is therefore considered representative of threats faced by other pollinator species (Ghazanfar et al., 2016). A large decline in monarch butterflies has been observed due to a loss of milkweed stems, largely attributed to agricultural expansion (Thogmartin et al., 2017). Current monarch conservation strategies involve increasing pollinator habitat, recommending that specifically >1.3 billion milkweed stems be planted in the United States (Thogmartin et al., 2017). Sufficient research has not been done to understand monarch feeding behaviors to best implement this habitat to successfully increase the population. Past research has observed larval feeding (Fisher et al., 2020) and oviposition (Haan & Landis, 2019) on the top portions of the plant where young leaves develop. Here, we investigate if immature milkweed leaves that are provided on the top portion of milkweed plants offer an advantage to monarch third-instar larvae. We quantified the area and biomass of milkweed, as well as differences in larval mass, instar progression, and survival when provided with four disks of only immature milkweed (treatment one), four disks of mature milkweed (treatment two), or a choice between two disks of immature and two disks of mature milkweed (treatment three). Finding an advantage to immature milkweed consumption may suggest that increasing the availability of immature milkweed, by mowing or clipping stems to encourage regeneration, may increase conservation success for monarch butterflies. This research may motivate future projects that further investigate trends in pollinator behaviors so that conservation efforts can be designed to align with insect biology, as innovating more successful conservation strategies is imperative for maintaining human and ecological health.

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