15. Colonization of the gut microbiome of the cabbage looper, Trichoplusia ni

Abstract

Gut microbiomes are the collection of microscopic organisms that live in the digestive track of other organisms. The influence of gut microbiomes on the health of their host organisms is widespread. For example, in humans, gut microbiomes have recently been linked to both obesity and Parkinson’s disease. In insects, interference with the gut microbiome is a potential new mechanism for pest control, and maintaining the gut microbiome of beneficial insects is important for ecosystem health. The purpose of this study is to understand the source of microbes that live in the gut of the insect Trichoplusia ni, also known as the cabbage looper. Previous studies indicate insect guts are often colonized by microbes living on the food they eat. To test the hypothesis that the gut of T. ni is colonized from microbes living on its food, T. ni was raised on organic green cabbage with a control group raised on an artificial lab diet. Bacteria were then cultured from food (artificial diet and cabbage), the dissected guts of the caterpillars raised on both diets, and feces from the caterpillars raised on both diets. Bacteria will be identified by biochemical tests using the BIOLOG system. If bacteria on the food and in the gut are the same, then it supports our hypothesis that T. ni guts are colonized from food. If the bacteria identified in the gut differs from that of the food, it suggests that the gut of T. ni is being colonized from a source other than food.