Systematics, Evolution, and Biodiversity
10-Minute Paper
Rebekka S. Janke
PhD Candidate
Johannes Gutenberg-University Mainz
Mainz, Rheinland-Pfalz, Germany
Filip Kaftan
Max Planck Institute for Chemical Ecology
Jena, Thuringen, Germany
Sarah Niehs
Leibniz-Institute for Natural Product Research and Infection Biology
Jena, Thuringen, Germany
André Rodrigues
São Paulo State University
Rio Claro, São Paulo, Brazil
Aleš Svatoš
Max Planck Institute for Chemical Ecology
Jena, Thuringen, Germany
Christian Hertweck
Leibniz-Institute for Natural Product Research and Infection Biology
Jena, Thuringen, Germany
Martin Kaltenpoth
Max Planck Institute for Chemical Ecology
Jena, Thuringen, Germany
Laura V. Flórez
University of Copenhagen
Copenhagen, Hovedstaden, Denmark
Encounters with natural enemies like predators, parasites or pathogens are a common threat, playing a key role in the evolution of virtually all organisms. Among insect antagonists, fungal pathogens are especially predominant and exert significant selective pressures on insect populations. In turn, insects have evolved defense mechanisms including immune responses, behavioral, mechanical or chemical defenses. Additionally, distinct life stages might also face different challenges and demand specific defense strategies: e.g. molting larvae and immobile eggs or pupae. Chemical defenses including defensive compounds are utilized by several insects and are often produced by themselves, but there is growing evidence that associated microbes can support protection against fungi and other enemies. In the beetle Lagria villosa (Tenebrionidae), bacterial symbionts of the genus Burkholderia produce antimicrobial compounds that inhibit fungal growth on the insect’s eggs and larvae and enhance their survival. Several Burkholderia strains are harbored in specialized symbiotic structures throughout the beetle’s life cycle and are only absent in male adults. One symbiont strain is predominant across life stages and consistently produces an antifungal compound, underlining its key role as a defensive symbiont. In larvae and in female pupae, the symbiotic bacteria are localized in three peculiar dorsal invaginations of the cuticle which, contrary to observations reported in the congeneric species L. hirta, do not close during development. Instead, the open structures likely facilitate the release of defensive compounds that aid in host protection during the vulnerable periods, while offering a suitable environment for growth and maintenance of the antibiotic-producing bacteria.