Garlic mustard, Alliaria petiolata, is an invasive herb that has outcompeted and replaced many native herbaceous plants. Garlic mustard has been studied for its chemical allelopathy; the ability to hinder growth of competing plants. Allelopathic compounds have been shown to inhibit mycorrhizal fungi, which have a mutualistic relationship with plant species that garlic mustard competes with. Inhibiting fungi thereby enhances garlic mustard fitness. It has been suggested that these anti-fungal compounds also inhibit entomopathogenic fungi, which infect and kill insects and arthropods like blacklegged ticks, Ixodes scapularis. This study investigated the possible relationship between garlic mustard and blacklegged tick populations through two experiments. One experiment measured the effect of garlic mustard soil and leaf extract on waxworm survival, where waxworms were used as a bioassay for the presence of fungi. The second experiment measured the abundance of blacklegged ticks found among plots of varying densities of garlic mustard and native herbaceous plant species. My results indicate that garlic mustard soil significantly increases waxworm survival (P <0.0001); however, there was no significant relationship between garlic mustard prevalence and tick abundance. The discrepancy in results between my lab and field studies lead me to conclude that waxworms are more susceptible to entomopathogenic fungi than ticks are, and are therefore a poor model for blacklegged tick survival. These findings indicate that controlling garlic mustard will likely have no effect on tick populations or the spread of tick-borne diseases.
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