The potential impact of ecological and geographical parameters on the spread of the invasive pest Nezara viridula.
The species Nezara viridula (L.) or green stink bug is one of the most recent non-autochthonous species that invaded agroecosystems in our country. The lack of natural enemies makes this insect rapidly spreading from the locality to the locality and from the geographic area to the other. It is not known exactly what causes enlargement to geographically or ecologically different areas. Globally, the insect is present both in warm and temperate areas. At Europe level it is found in almost all geographic points except the northern point. The observations of this scientific paper have been made in the southwest of Romania, more precisely at the level of the Caras-Severin County, which has a great variety of relief forms, from the plain to the mountains (from 168 m to 1000 m). The effective or size of the insect population at a given time, such as spatial distribution, has been the main parameters analyzed in terms of temperature and humidity but also geographical altitude. The observation period was in June-October of 2016 and 2017. Because they are large insects, trapping them with pheromone or colored traps is not conclusive and rather quantification by direct observations on the preferred plants (tomatoes, cucumbers, beans). To analyze population size and distribution in 8 different areas, 10 samples (one monthly sample/area) were processed. Correlations between environmental factors (temperature, humidity) have shown that high temperatures and low humidity favor activity and insect movement. The great presence of the species was mainly observed in areas with lower altitude of the county and less or not in high altitude areas, respectively at values ranging from 168 to 300 m.