Maize has been and continues to occupy a major place, being one of the most cultivated plants in Europe. Romania and, in particular, the western part of the country provides a great deal of corn production. As such, special care should be taken to protect these plants against harmful organisms and especially insects. There are currently some species that affect corn crops, and these include Diabrotica virgifera virgifera Le Conte (western corn rootworm), Ostrinia nubilalis (European corn borer) and Helicoverpa armigera (corn earworm). All three species have one particularity. So, Diabrotica is an invasive species that has a great ability to move and few natural enemies. Ostrinia is hard to fight, and there is no clear strategy at the moment. Helicoverpa is known to be highly resistant to insecticides, as well as the previous species. Taking into account all this, in the present paper we have proposed to evaluate the current state of population density of the above-mentioned insects from 10 different maize hybrids. The corn hybrids tested were selected according to the maturity group and their availability on the market. These were included in different maturity groups, such as semi-early, early and semi-early. The FAO classification included groups 300 and 400. The test site was Nerau in Timis county (western Romania) and the period covered 2 years, 2015 and 2016, respectively. Assessment of the population level of each species has been done specifically, depending on the size of the insect and the possibility of better catching them. Thus, colorful panel traps for the species Coleoptera and box-type traps for butterfly species were used. Traps were placed 3 in each batch following the manufacturer's instructions. In all the experimental lots the three harmful species were present in great dimension but the population level did not differ much from hybrid to hybrid.

Diabrotica virgifera, Ostrinia nubilalis, Helicoverpa armigera, corn

biology

Presentation: poster