Effects of Fungicide Residues on the Growth and Feeding of Monarch Butterfly (Danaus plexippus) Larvae

The use of pesticides continues to be a prominent approach for improving crop productivity in the agricultural sector. While these chemicals offer significant advantages in controlling infections and infestations caused by pests, their residues can have adverse effects on non-target species, like milkweed, which is frequently present in agricultural environments. Prior research has indicated the adverse impact of various pesticide residues on monarch butterfly larvae, but limited studies exist concerning the effects of fungicides. This investigation seeks to explore the impact of two commonly-used, persistent fungicides (cyprodinil and difenoconazole) on monarch butterfly caterpillars using three milkweed species: Asclepias syriaca, A. curassavica, and A. asperula. The selected species encompass a range of low to high concentration cardenolides, defensive chemicals known for their toxicity to many organisms. The research employed field-revelent fungicide doses to leaf punches of the three milkweed species for caterpillar feeding. The results indicate that Asclepias asperula is consumed the least, followed by A. syriaca, and then A.curassavica. Furthermore, difenoconazole shows no significant correlation between caterpillar mass and dosage. In contrast, Cyprodinil demonstrates a decrease in caterpillar mass as the dosage increases. This research deepened our understanding of the fungicide residues on non-target species and will assist the agricultural community in identifying alternative methods for chemical application that minimize adverse effects on nearby non-target species.

I am extremely grateful for the opportunity to participate in the Boyte Thompson Institute Research program. I have acquired diverse research skills and knowledge that are crucial to my career interests as a researcher. Additionally, I have formed unforgettable friendships with cohort members and lab colleagues whom I highly respect, and who have taught me numerous valuable lessons. My overall experience in Ithaca and at Cornell has been nothing but filled with happiness and satisfaction. Conducting experiments in the lab, swimming in the many gorges, or dancing in the festivals have provided me with the best summer experience that I will never forget.