13. Bugs in Bugs: Analysis of microbiota of Trichnoplusia ni Larvae

Abstract

All multicellular organisms including plants and animals harbor a community of microbes called the microbiota. The gut microbiome plays an important role in digestion, immunity and overall health of an animal. Research has shown that the insect microbiome is associated with resistance to natural invaders, virulence, digestion, and reproductive success. The insect microbiome may also metabolize defensive compounds, and influence the ability of insects to associate with certain host plants. Recent research suggests that hornworm caterpillars (Manduca sexta) have no permanent microbiome; instead acquiring transient microbes from the plants they eat. In this project, students from two courses (BIOL1108K and BIOL2500L) collaborated to understand the acquisition of gut microbiome of Trichnoplusia ni, a nocturnal cabbage looper or commonly referred to as owlet moths. Biology 1108K collected fecal samples from T. ni larvae fed on various pre-selected plant diet. The fecal samples were suspended in saline, swabbed on nutrient agar plates, and incubated for 24 h at 37˚C. Bacterial colonies that appeared on these plates were then analyzed and characterized by BIOL2500L students. Our group comprising of four students analyzed three bacterial colonies using microbiological techniques learned in BIOL2500L. We investigated the colony and cell morphology, Gram reaction, antibiotic resistance and biochemical features of all three bacteria. We identified all three bacterial colonies to be Gram-positive Staphylococcus sp, which is interestingly part of the normal skin microbiota suggesting that humans and insects may share similar microbiota.