Beetle Update – Blog Post 4

At the beginning of last week, I was ready to begin introducing the longhorned milkweed beetle larvae to the experimental common milkweed plants. I first completed a destructive harvest of thirty experimental plants. I bagged the aboveground and belowground tissues for each plant and then placed them in a drying oven so that I will be able to later weigh the tissues. I will use these weights to construct a model of how belowground biomass and aboveground biomass relate to each other. On Tuesday morning, I was ready to begin removing the larvae from the kiddy pool where they had been feeding on the small (25-35 cm tall) milkweed plants. I looked for larvae for about 3 hours and very sadly found none. I removed all the plants from the kiddy pool and examined their roots in the greenhouse with an optivisor before bringing the roots down to the lab to look at them under the dissecting scope. I saw a few really tiny clear worms and a few really tiny shiny bugs under the dissecting scope, but that was it.

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Blandy Experimental Farm & Presquile National Wildlife Refuge – Blog Post 3

We returned to Blandy Experimental Farm last week and spent three days doing pollinator watches. During each pollinator watch, which typically lasted between ten and twenty-five minutes, we recorded the species and visit duration of insects on an umbel of a common milkweed plant. An umbel is a cluster of flowers on a milkweed stem that emerge from a common point. Before starting each pollinator watch, we recorded some measurements for each plant, such as height and number of leaves, as well as recorded the number of pollinia that had been either inserted or removed from the umbel. Each umbel typically had between thirty and sixty flowers, and each flower contained five pollinia before any insertions or removals by insects. We used optivisors to carefully count insertions and removals after insects left the umbel. We also set up some video observations for twenty minutes per umbel. For these observations, we recorded the number of pollinia insertions and removals at the beginning and end of each video. We photographed images of the leaves of the videoed plants so that we will be able to use ImageJ to do some herbivory calculations later.

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The Beetle Eggs Have Started Hatching! Blog Post 2

On Wednesday of last week (June 19th), I examined the dry grass stems where the longhorned milkweed beetles oviposited and discovered that many were filled with eggs and a few hatched larvae! Each of the nine beetle habitats, which are ventilated rearing boxes in the greenhouse containing the stems, sand, fresh milkweed leaves, and the beetles, contained approximately twenty stems and between ten and fourteen beetles. Each box contained an average of just over 500 eggs, which is much more than we originally expected.  I transferred the stems from the beetle habitats to a kiddy pool containing over thirty-five, small (25-35 cm tall) milkweed plants. The larvae will feed on the roots of these plants in order to grow a little bit bigger before they are introduced to our experimental plants.

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Greetings From Blandy Experimental Farm! Blog Post 1

The first week and a half of research is off to a great start! We spent the first half week learning about lab protocols, milkweed plant care, and the spectroradiometer. We used this instrument to take absorbance readings for leaves from all 122 of our common milkweed plants in the greenhouse. We also collaborated with Professor Williamson’s lab on an experiment to see if cardenolides (a compound in milkweed) have antimicrobial properties. The initial results showed that they do not, but we are going to revise some elements of the experiment and try it again.

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Effects of Longhorned Milkweed Beetle Root Feeding on Re-sprouting in Common Milkweed

Common milkweed (Asclepias syriaca) is an essential source of food for monarch butterflies (Danaus plexippus) as caterpillars, and there are concerns about the decrease in the monarch butterfly population. The decline in monarchs has been linked to a decline in common milkweed. Common milkweed plants are also where the longhorned milkweed beetle (Tetraopes tetrophthalmus) spends its larval and adult stages. The larvae eat the roots, and the adults feed on the leaves. This feeding means that the beetles affect multiple parts of the plant throughout their life cycle, suggesting that the beetle could have a greater impact on milkweed than the monarch does. However, not much is known about the impact of the beetle’s feeding on common milkweed. My research project aims to fill this gap.

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