Plant Fragments Prevent Infections

six white eggs with brown spots from a blue tit bird, seen surrounded by white and grey feathers and then straw and grasses, nest appears to be in a tree trunk

Biological Strategy

Eurasian blue tit

AskNature Team

Image: NottsExMiner / Wikimedia Commons / CC BY SA - Creative Commons Attribution + ShareAlike

Regulate Reproduction or Growth

Reproduction and growth are two physiological processes that occur in all living systems. There are situations when conditions are right for both, and other situations when continuing either harms the living system because both have a very high energy cost. Reproduction and growth are unique in that both can stop until conditions improve, although stopping either for an extended time can cause problems. An example of regulating reproduction is a process called delayed implantation or embryonic diapause found in some mammals, such as otters. An otter’s embryos sometimes temporarily cease developing and won’t develop further until the female senses that conditions are suitable.

Search this Function

Protect From Microbes

In living systems, microbes play important roles, such as breaking down organic matter and maintaining personal and system health. But they also pose threats. Bacteria can be pathogens that cause diseases. Some bacteria create colonies called biofilms that can coat surfaces, reducing their effectiveness–for example, inhibiting a leaf’s ability to photosynthesize. Living systems must have strategies for protecting from microbes that cause disease or become so numerous that they create an imbalance in the system. At the same time, living systems must continue living in harmony with other microbes. Some living systems kill microbes. Others repel without killing to reduce the chances that microbes will adapt to the lethal strategy and become resistant to it. For example, some pea seedlings exude a chemical that inhibits biofilm buildup.

Search this Function

Birds

Class Aves (“bird”): Eagles, hawks, sparrows, parrots

Birds are evolutionary engineering marvels. They are descended from dinosaurs, but are far from our idea of heavy, scaly reptiles. Of the specific adaptions that set them apart, most notable is flight—although some mammals can fly, birds take the prize for abundance in the skies. Many birds have hollow, lightweight skeletons and specially-designed wings to help them stay aloft. They also have feathers made of keratin that help them stay warm, attract mates, and improve navigation and aerodynamics in flight. In contrast to their dinosaur ancestors, they lack true teeth and have replaced them with specialized beaks and bills.

Search this Living System

Blue tit females protect their chicks from pathogenic bacteria by selectively placing fragments of certain aromatic plants in their nests.

Introduction

Blue tits make nests in holes and hollows that can become quite warm and damp as the chicks mature. This creates an optimal environment for the growth of pathogenic bacteria and parasites like blow fly larvae that can create severe health problems for the chicks.

Image: Andreas Trepte /

The Strategy

To promote healthy growth in the chicks, female blue tits actively seek out fresh fragments of aromatic plants like lavender, yarrow, daisy, and apple mint to place in the nest cup.

The complex bouquet of aromatic biochemicals produced by these plants have long been known for their antimicrobial characteristics, though the biochemistry is still poorly understood. However a study from 2009 found that the various plant fragments conferred greater health and survivability by reducing the bacterial richness on the chicks.

Fresh aromatics were also found to exert a significant effect on chicks infested with blood sucking blow fly larvae. While the material did not appear to affect the larvae directly, they were found to exert a significant effect on the density of bacteria on the chicks. Sparsely placed bacteria are not able to form biofilms and other communities that increase their pathogenicity. Presumably, the chicks benefit from this bacterial reduction by being able to devote more of their nutrient resources to growth rather than their immune systems, leading to overall stronger and healthier chicks. Adult blue tits did not experience any significant decrease in bacterial infection from these plants.

The Potential

Fresh plants and herbs have been used by humans for various purposes (including as an antibacterial substance) across cultures and throughout time. Mimicking blue tits’ particular blend and application methods could lead to new insights and applications for humans at domestic as well as industrial scales.

Last Updated March 24, 2020

References

“Birds use fresh plants to limit the growth of nest microorganisms. On Corsica, blue tits (Cyanistes caeruleus) incorporate fresh fragments of aromatic plants into their nests. These plants do not reduce infestation by nest ectoparasites, but have been shown to improve growth and condition of chicks at fledging…Aromatic plants significantly affected the structure of bacterial communities, in particular reducing bacterial richness on nestlings. In addition, in this population where there is a strong association between bacterial density and infestation by blood-sucking Protocalliphora blow fly larvae, these plants reduced bacterial density on the most infested chicks. Aromatic plants had no significant effect on the bacteria living on adult blue tits.” (Mennerat et al. 2009:849).

Journal article

Aromatic plants in nests of the blue tit Cyanistes caeruleus protect chicks from bacteria

Oecologia | 25/07/2009 | Adèle Mennerat, Pascal Mirleau, Jacques Blondel, Philippe Perret, Marcel M. Lambrechts, Philipp Heeb

embedly preview

AskNature