THE EVOLUTIONARY AND FUNCTIONAL SIGNIFICANCE OF GUT MICROBIAL SYMBIOSES IN HONEY BEES, BEETLES, AND APHIDS

Abstract

Symbiotic associations of insects with microorganisms have great importance in insect ecology and evolution. The digestive systems of insects offer unique habitats for several microbial communities that are able to fulfill a number of biological roles in host organisms, such as nutrient uptake, metabolic control, immunological defense, and detoxification of hazardous chemicals. Therefore, the gut microbiome is considered one of the key factors in insect survival, adaptation, and ecological success in various environments. Gut microbes of insects are important players providing immunological defense, nutrient uptake, metabolic regulation, and detoxification of hazardous compounds. Thus, the gut microbiome is an important factor determining the ability of insects to adapt to and survive in different environments. The diets of many insects consist of foods that are poorly nourishing or have some chemical defenses, including pollen, sap from trees, or wood itself. Many insects cannot degrade complex nutritional substances in food sources by themselves. Insects may generate essential amino acids, degrade carbohydrates, and transform components of their diet into a usable form owing to the enzymatic actions performed by friendly bacteria in the intestines. The metabolic pathways lead to inter-related biological systems which aid the development and reproduction of insects. Insects such as aphids, beetles, and honeybees are used as models to study the interactions between hosts and microbes. Honeybees rely on a specific but simple composition of gut microbes in order to facilitate digestion within their colonies. Aphids maintain bacterial symbionts that provide necessary amino acids not available from their plant-based diet. Beetles are able to adapt to different environments due to the presence of various microbes which assist in digestion and detoxification.