Browsing tag: bioinsektycyd

Bakterie Xenorhabdus i Photorhabdus, nicienie entomopatogeniczne i owady – funkcjonowanie w złożonym układzie symbiont – pasożyt – żywiciel

Bacteria Xenorhabdus and Photorhabdus, entomopathogenic nematodes and insects – their role in the complex symbiont-parasite- -host relationship
K. Kucharska, D. Kucharski, B. Zajdel

1. Wprowadzenie. 2. Powstawanie pasożytnictwa nicieni u owadów. 3. Funkcjonowanie układu nicienie entomopatogeniczne – bakterie mutualistyczne – owady. 4. Mechanizmy odpornościowe owadów. 4.1. Odporność fizjologiczna: behawioralna. 4.2. Odporność fizjologiczna: bariery anatomiczno-fizjologiczne. 4.3. Odporność nabyta: polipeptydy i białka odpornościowe. 4.4. Odporność wewnętrzna: komórkowa i humoralna. 5. Mechanizmy odpornościowe nicieni entomopatogenicznych i mutualistycznych bakterii. 6. Podsumowanie

Abstract: Bioinsecticides based on nematodes are becoming increasingly popular agents for pest control. Nematodes used in these insecticides owe their properties to the presence of symbiotic bacteria. Representatives of two genera – Xenorhabdus and Photorhabdus can be found in the digestive tracts of, respectively, Steinernematidae and Heterorhabditidae nematodes. Nematodes have a number of properties, allowing them to penetrate the host integument, breaking the immune defenses, multiplicating in his body, killing the host and finally producing invasive forms, viable in the external environment. Bacterial symbionts are responsible for some of these abilities, since they produce toxins lethal to the victim and maintain adequate conditions for the development of their vectors. The bacteria are an example of one organism living in another as a symbiont, and functioning as a pathogen for another one. The relationship nematodes-mutualistic bacteria-insect is formed. The immune system has the ability to fight against insect entomopathogens, however, a variaty of adaptation mechanisms of parasites and symbionts, molecular mimicry and destruction of phagocytic cells among others, enables them to survive in the host. With an effective biocidal properties, nematodes which are in a mutualist relationship with bacteria, become perfect and safe for use in the environment pest control agents. Transgenic plants producing Xenorhabdus and Photorhabdus toxins can be as effective as those producing Bacillus thuringiensis toxins.

1. Introduction. 2. The emergence of nematode parasitism in insects. 3. System functioning of entomopathogenic nematodes-mutualistic bacteria-insects. 4. Defense mechanisms of insects. 4.1. Physiological resistance: behavioral aspect. 4.2. Physiological resistance: anatomical-physiological barriers. 4.3. Acquired immunity: polypeptides and immune proteins. 4.4. Internal resistance: cellular and humoral factors. 5. Immune mechanisms of entomopathogenic nematodes and mutualist bacteria. 6. Summary