We will compare the damaged plants (mechanical and jasmonic acid spray) with a regular amount of fertilizer and the non-damaged plants with a regular amount of fertilizer in order to analyze the effect of spraying jasmonic acid onto plants. We will compare them by measuring how tall the plants grow, the rate they grow, the surface area of the leaves before and after, and if there are any signs of chlorosis or necrosis. By doing so, we will be able to see how mechanical and jasmonic acid damage affects new versus old growth on the plant.
You are here
120 tomato plants will be used in the study. 100 of the plants will receive a form of damage to their leaves by caterpillars eating bits of leaves off of each plant, the remaining 20 will serve as a baseline. The caterpillars will be left on the plants for enough time to do a measurable/visible amount of damage to the plant. 75 tomato plants will receive JA, there will be three groups receiving treatment and one group will receive no treatment (this will be our control). 25 will receive five sprays of JA, 25 will receive three sprays of JA, 25 will receive one spray of JA, and 25 will receive no treatment of JA (this way, we can see if too much JA hurts the plants, if any amount of JA hurts the plants, or if more JA applied to plants then the plants will repair themselves faster or better than they would have without the extra spray). The responses could be measured by weighing the plants before and after to see if there is a change in biomass. They could also be measured visually by analyzing the plants to see which ones look healthier or if their leaves grew back entirely and then some.
In the bumble bee (Bombus impatiens), the gut parasite Crithidia bombiis related to the causes of Chagas disease and Leishmaniasis in the bumble bee. The parasite is transmitted via ingestion of cells in feces of infected bees, and is present in 80 percent of the Bombus impatienspopulation in New England. In the lab, we will be infecting bumble bees with the gut parasite through a nectar feeder and randomly assign which bees get the treatment. We will then leave them alone for a week, dissect their guts, and count the amount of Crithidia bombicells.
Plant defense mediate tri-trophic interactions. A plant’s response to a threat can influence herbivore mutations and eventually predator mutations. Plant defenses directly reduce herbivore performance, but they can also indirectly benefit herbivores because they can acquire new traits from the new chemicals made by the plant they are consuming. Since pollinators are herbivores (they consume nectar and pollen from plants), they also can acquire new traits from the nectar and pollen containing new plant defenses.
Since 1990, there has been a 25% decline in the United States in vertebrate pollinators and 200 vertebrate pollinator species are near extinction . The majority of our staple crops are wind-pollinated and don’t require vertebrate pollinators, but roughly a third of our crops would not exist without vertebrate pollinators (many types of berries, nuts, vegetables, cotton, coffee, around 90 major crops). Vertebrate pollinators provide 30 billion USD of pollination services in the United States alone, and 200 billion USD globally. The impact of the loss of pollinators to the global agricultural system would be great as well as the to plant species that we do not cultivate.
We will be doing an experiment which involves spraying jasmonic acid onto damaged tomato plants (Solanum lycopersicum). This tomato plant species belongs to the Solanacaefamily, which includes eggplants, potatoes, and tomatoes. The reason this species of tomato will be used is because it has well characterized chemical defenses. However, the nectar-less flowers will require pollination by bees. In order to provide the mechanical damage we want to apply to the plants, we will use the tobacco hornworm (Manduca sexta). This worm is native to New England and is a well-known crop pest on tobacco and tomato plants.
Figure 1. Scarlet Macaw (Ara Macao) and Blue and Gold Macaw (Ara ararauna). The two different species of Macaw live in the Amazon rainforest. They are a very social and intelligent bird, making them popular as pets. https://www.flickr.com/photos/timpeartrice/6104560916/sizes/z/
In 1995, Minnesota middle school students sampled frogs in a nearby pond and found that half of them were deformed, and it was discovered soon after that this was a widespread occurrence. A total of 8 frog and toad species were affected by this. Approximately 0.2% of frogs found in the area were deformed from 1973 to 1993, and that percentage increased to 2.3% by 1996. The cause of this deformity was found to be a species of trematode, Ribeiroia ondatrae, which are flatworm parasites that cause deformities and sometimes death in frogs. Trematode larvae in frogs cause cysts. If the cysts are in a developing tissue, it can cause a deformity; for example, if the cysts are found in a tissue that is developing legs, the cysts can cause extra or truncated legs. The occurrence of deformities in the frogs in the area had increased due to runoff of Atrazine, an herbicide (which is banned in the European Union and other developed countries) which kills plants in a pond, causing them to decompose and ultimately cause eutrophication of the pond. This eutrophication of ponds led to more snails in which trematodes begin their lives. The trematodes then move from the snails into the frogs, causing the deformities.
In order to determine the power of an experiment, the experiment must be conducted several times. If the experiment is successful or shows similar results the majority of the time, the experiment would have a great power. Initially, before conducting an experiment several or dozens of times, the initial experiment must be well thought out. An experiment should have a high (if cost is an issue, then reasonable) amount of replicants. All experiments will have an experimental noise which will cause variation, but if there is an alarming amount of variation in the initial experiment, there is something wrong with the experimental design, there could be another variable interfering in the experiment which isn’t realized, etc. A simple experimental design has more power than a very complex one. The P-value cutoff should be around 0.05, meaning that the majority of the time, the experiment is accurate and the results are more easily proven. Finally, an experiment which shows a strong treatment effect will have greater power than an experiment which does not.
Jasmonic Acid is the hormone released in plants when they experience damage from herbivores in order to induce defenses. Although damage to plants often results in fewer or less attractive flowers or fruits, recent work has shown that jasmonic acid also induces nectar productions in some systems. When a caterpillar eats a part of a leaf, the plant will produce jasmonic acid to repair itself after the tissue is lost. Simply cutting a leaf will not induce jasmonic acid production because there is an enzyme in the saliva of the caterpillar which induces the production of jasmonic acid. However, spraying jasmonic acid on the plant will increase the production of jasmonic acid, but will not affect the tissue negatively.