Apart from humans, many organisms acquire beneficial bacterial partners from the food that they eat. But what about generalists, whose diet can vary every day? We asked whether the bacteria in the diet of the red flour beetle – a grain pest found across the world – impact the beetles’ fitness in different diets. For these beetles, flour is not only their diet, but also the environment in which they live. Aparna found that beetles derive many fitness benefits from microbes in wheat flour, which they have used for many generations. But microbes from the new diets are not important for beetle fitness. So, diet shifts can be problematic for generalists, because their bacterial partners may be missing. Read the paper here.
Bacteria are so small and so ubiquitous that it seems like they should be found everywhere. But recent work shows that much like animals and plants, most bacteria have discrete distributions. We asked: does host association shape bacterial distribution in nature? In Pratibha’s first paper from the lab, we describe how bacteria from the genus Methylobacterium are distributed across nearly 40 different rice landraces from Arunachal Pradesh and Manipur. Collaborating with the labs of Shivaprasad and Radhika at NCBS, we found that bacterial carbon-use phenotypes are largely shaped by the landrace they inhabit. Suprisingly, sugar availability on rice leaves does not correlate with the carbon-use phenotypes, leaving us with many new questions. For more, read the paper. Meanwhile, enjoy this lovely illustration by Pranjal Gupta!
Kruttika’s work testing the impact of butterfly caterpillar microbiomes on growth and survival is published! This was a major collaborative effort with Krushnamegh Kunte, and very new kind of work for our lab. The results were puzzling because unlike patterns from other insects, butterflies seem to be just fine without their bacteria. But in conjunction with Rittik and Ashwin’s recent results with dragonflies, it seems that we’ve uncovered one end of the spectrum of host-microbe interactions. The end that spells “meh!” rather than “I need you”. Here’s a cartoon summary of the work by Kruttika and Shreya. Also read a lay summary here; or read the paper for more details!
Rittik Deb and Ashwin Nair’s paper on the gut bacterial communities of dragonflies is out! We sampled several species of dragonflies from different locations in India, and found that gut bacterial communities varied across host species, location, and season. For some of the dragonflies, we were also able to analyse gut contents, and found that these “generalist predators” eat quite different meals that probably end up introducing distinct bacteria in their guts. So, unlike in most other insects, dragonfly gut bacterial communities seem to be transient and are neutrally assembled (rather than host-selected). Read the paper for more details. Meanwhile, enjoy this beautiful summary of the paper by Pranjal Gupta!