The Effect of Novel Animal Models on the Sexual Reproductive Pathways of Asclepias syriaca

One of the most beloved insect species alive today is the Danaus plexippus, or the monarch butterfly.  Ominously, they have seen concerning population declines which have been strongly linked to a decline in milkweed, specifically Asclepias syriaca (Common Milkweed) populations, the host plant of the Monarch caterpillar.  Between 1999 and 2010, the milkweed and monarch populations decreased by 58% and 81% respectively (Pleasants and Oberhauser 2012), highlighting the need for conservation.  While we know a great deal about monarch and milkweed interactions, we know comparatively less about the milkweed interactions with other specialist insects.  In addition, much of the literature deals with the milkweed’s ability to propagate itself through asexual budding, while the sexual pathways necessary for long term survival remains receive less attention.  By learning more about the milkweed’s sexual pathways, conservation efforts can be more targeted to increasing genetic diversity more efficiently, raising the likelihood that milkweeds can make a comeback.

My research will be focusing on the interactions between animals, specifically insects, and the milkweed’s sexual reproduction pathways.  This experiment will be done in two stages, both occuring at Blandy Experimental Farm.  The first stage will involve the milkweed herbivore, Tetraopes tetrophthalmus or the longhorned milkweed beetle.  As with all herbivores, the milkweed would seemingly only be hurt by this relationship.  However, it has been noted by keen members of the Dalgleish lab that these beetles have been seen carrying pollinia, or packs of pollen, around on their legs.  If this is the case, then the beetles potentially could act as a pollinator, which would end up benefiting the plant.  Pollination can only occur, however, if the pollinator can both remove and insert pollinia efficiently, known as pollinia transfer efficiency (PTE).  The objective of this portion would be to determine a potential beneficial relationship between the beetles and the milkweed, as measured by the PTE of T. tetrophthalmus.  The next portion of the experiments focus on establishing the population of A. syriaca pollinators located in Blandy.  Using both in person and video observations, the pollinators will be recorded down to the genus or species, depending on the ability to identify in the field.  For the in-person observations, not only will the identity of the pollinators be recorded, but also the insertion and removal of pollinia.  With this, a baseline of population and efficiency of pollinators for the common milkweed in Blandy will be quantified.

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