Evaluation of corn hybrids resistance against european corn borer (Ostrinia nubilalis hbn.)

Abstract

Тhe main corn pest in the forest-steppe zone of Ukraine is European corn borer. Crop Losses from this pest account for 12–25%. Therefore, the search of immune hybrids of corn to this phytophage is extremely important. 11 corn hybrids of different stages of maturing selected by GU Institute of grain crops NAAS of Ukraine and 2 hybrids of foreign selection were using for resistance analyzes In 2017–2019.

The following indicators used to evaluate the additive resistance: the number of eggs per 100 accounting plants, the percentage of plants with eggs, and the percentage of damaged by caterpillars plants.

The technique of resistance point’s determination by the percentage reduction of damage (damage, population) of plants compared to the reference variety was improved.

The system of the number accounting, population of plants by eggs and damage by the European corn borer  caterpillars made it possible to identify two types of resistance antibiosis (inhibition of phytophage development) and antixenosis (non-adaptability of plants for laying eggs by a pest).

Data analysis of 2017–2019 show that resistance of corn hybrids to European corn borer by antixenosis type was lower (5points). Except DN Svityaz – 5,6 points and DKS 3472 (Monsanto) – 5,7 points (middle-early).

By the type of antibiosis all research hybrids had high resistance (5 points) except Monica 350 MB hybrid (4,8 points). Early maturing hybrids had average resistance 6,8 points (5,7–7,5). The highest point of resistance observed on DN Positiv corn hybrid – 7,5 points. Lower level of resistance – 5,6 (5,1–6,9) was among middle-early hybrids. The highest level of resistance from this group had DN Svityaz hybrid (6,9 points). More lower level of resistance – middle-early hybrids 5,4 points (from 4,8-5,8). Among this hybrids the highest level of resistance had DN Demetra (5,8 points), the lowest – Monica 350 MB (4,8 points).

Having rating by the types of resistance to antixenosis and antibiosis, we determined the additive level of hybrids, which made it possible more fully characterize the resistance of corn hybrids to butterflies of European stem borer. Consequently, Pochaevsky 190 MB (5,4 points), DN Positiv (6,2 points) were resistant among early maturing hybrids; among middle-early – DN Svityaz (6,3 points), DN Vita (5,3 points) and DKS 3472 (Monsanto) (5,4 points); DN Demeter (5,1 points).

Therefore, in order to increase the effectiveness of protective measures and to avoid possible negative consequences when applying insecticides during the formation of milky-waxy ripeness of corn grain, it is necessary to use more widely persistent corn hybrids and to deepen the study of the mechanisms of plant resistance against pests. Therefore, the study of the resistance of modern hybrids, and especially domestic ones, against the European corn borer is extremely relevant and indicates the real possibility of solving the problem of protecting plants against this phytophagy by using of resistant hybrids.