Orthoptera insects (Insecta: Orthoptera) of extreme eastern part of Georgia on the example of ecotones of the David Gareja Hollow

Insects are one of the most successful invertebrate animals. There are three main reason of their evolutionary advancing. 1. to conquest atmosphere; 2. Cephalization (i.e. head is differentiated from other part of body) 3. Pupal stage in ontogenesis (Holometabolous). Orthoptera is distinguish from holometabolous insects. It has no pupal stage in life cycle i.e. belongs to hemimetabola, wich is an incomplete metamorphosis despite they are as successful as other ordos of insects such as: Lepidoptera, Coleoptera, Diptera, Hymenoptera they all are characterized by a complete metamorphosis. Orthopterans develop in following stages egg, nymph and adult stages. The female grasshoppers after mating dig a hole in soil and lay a group of the eggs in this hole, which are packed in the adhesive substance. After a few weeks of development, most species of eggs went diapause stage (hibernation) throughout autumn and winter. Eggs in the soil are less vulnerable to the abiotic and biotic factors of the environment. This is the essence of the fact that the Orthopterans did not pass on the characteristic anatomic peculiarities in the class of insects which is- Holometabolous development. “Cementing” eggs are a well compensation of pupa phase. Orthopterans as plant consumers and in some cases bring greatest harm for agrocenosis and biocenosis. The main essence of their harmfulness is made by incredible swarm. This is one of the most selective feature of the group in their behavior ability. For example depending the environmental conditions they change their solitary life mode and turned into large group, i.e. gregarious phase of life. Insects changes to gregarious phase are caused by hormone (serotonin). Excreted hormone is initiation factor and as a result, as it was mentioned insect changes behavior. In the enormous swarms there are millions specimens of grasshoppers that are stretched hundreds of kilometers and are destroying all the green in there way. Our investigation habitats were represented in aridal region of eastern Georgia, particularly the most driest (about 200 mm annual average rainfall) David gareja hollow. It was collected 42 specimens of 3-4 species of Orthoptera. Among them Italian grasshopper during some years turn into gregarious insects and made harms to green plants. In future I am going to collect Orthoptera specimens, define their taxonomy and evaluate their importance.

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