PATHOMORPHOLOGICAL CHANGES IN THE INTESTINE OF BEE AND IMMUNE REACTION TO MICROSPORIDIUM NOSEMA APIS

Abstract

Honey bees (Apis mellifera) host a wide range of parasites, some of which are known to cause dramatic colony losses, as reported in recent years. To counter parasite threats, honey bees have an efficient immune system. Because immune responses are predicted to impose significant physiological costs on infected individuals, they are expected to interact with other life traits that ultimately affect the productivity and fitness of the entire bee colony. Here we tested whether the initial onset of infection adversely affects the gut of worker bees, which is quite an organ of all living organisms and affects all major functions, peristalsis, absorption of nutrients, etc. To do this, we artificially infected young worker bees with the worldwide pathogen Nosema apis, which is recognized and destroyed by the honey bee's immune system. We compared their survival and behavior compared to uninfected individuals from the same apiary and even from the same bee colony. The way of life of social hymenoptera insects, like all ants, as well as some bees and wasps, leads to the fact that related individuals live in close proximity to each other within the bee colony, which creates very favorable conditions for parasites to spread and reproduce. It is well known that bees contain a wide range of different parasites, such as viruses, bacteria, fungi, protozoa, as well as arachnids or other insects that can pose a serious threat to bees. Social insects also have individual innate immune systems, and an individual's ability to fight off parasites is central to the survival of the bee colony. These consist of a mechanical response against large parasites (through processes such as encapsulation and melanization) within cells, as well as a humoral response mediated by antimicrobial peptides, proteins, and other cytotoxic compounds. The activation and use of such defense mechanisms is a complex function and is assumed to compromise other life features of the insect. For example, immune activation can reduce the survival of infected worker bees and affect their reproduction by directing their energy reserves to immunity. A trade-off between immunity and other features of the life cycle is also present in mothers. N. apis infections are often phenotypically expressed by dysentery and increased levels of insect hunger, leading to increased honey and sugar consumption. N. apis is generally referred to as a low-virulence parasite, and the parasite's spores are indeed recognized and destroyed by the honey bee's immune system. Despite the fact that now the Nosema microsporidia is spreading practically all over the world to its definitive host, the mechanisms of its influence on the body of bees, the pathogenesis of the causative agent and how bees react are not sufficiently studied. Therefore, it was decided to conduct a broad characterization at the histological level. The study of the tissues of the intestinal epithelium can explain the early mortality of bees when affected by nosemosis. A study of the bee gut, which is an interesting model system for studying insect defense responses.