Baseline Study of Herbivore Preferences to Plant-vigor: A Distance-Mentored Undergraduate Research Experience

Abstract

Plants conspicuously display their energy production by a number of phenotypic characteristics; such as the number of leaves, flowers, pods, and their growth rate. When under predation by an herbivore, these factors can change significantly. Using such indicators to classify plant-vigor or health, leaf-area measurements of Brassica rapa were used to determine if the herbivores themselves select for healthier plants. The herbivore used in this study is the common field cricket (Acheta domesticus). Wisconsin Fast Plant cultivars of Brassica were grown in eight separate terraria. Two varietals of Brassica (green and yellow) were planted, resulting in four terraria for each type. Control groups (two green and two yellow) have no herbivores added to the tanks. Conversely, the experimental groups have Acheta applied to them. Variables such as the number of leaves, flowers, seed pods, height, and cricket mortality, were measured once a week for seven weeks. Photographs of leaf-area consumed will be analyzed using ImageJ, a computer program used in scientific research. Dry biomass will also be measured as a secondary means of measuring herbivory. Preliminary data shows a significant influence of seed pod production in the experimental groups and also a lack of development in yellow varietals compared to green Brassica. Once the leaf-area of predated leaves and the biomass of the terraria are analyzed, then correlations between herbivore selection and plant-vigor can be assessed. Congestion within the green tanks and general collateral damage during data collection has no doubt influenced the numbers received. This can be amended, as every stem that snapped was recorded in a journal, and such data can be omitted to eliminate unwanted variables.