Research regarding the Ostrinia nubilalis Hbn. (Lepidoptera: Crambidae) attack at maize crops under the central of Moldova conditions, Romania

Abstract

The Ostrinia nubilalis Hbn. larvae causes attacks and production losses by feeding with different parts of the plant (stem, cobs, inflorescence). The insect is spread throughout Romania, the frequency of attack is, on average, between 30.3% and 70%. The importance of Ostrinia nubilalis Hbn. attacks produced at maize led to the initiation of studies in 2017 at ARDS Secuieni with the purpose to establish the role of technological links in reducing the attack caused by insect larvae. The result obtained regarding the experimentation of five sowing epochs highlighted the high attack on larvae of maize sown in epochs IV and V in comparation with the optimal epoch. The attack produced by larvae at different genotype under the conditions of Central of Moldova, was between 28.59% (Turda 248) and 35.83% (Turda 165), compared with the average experience of 33.34%. Regarding the positioning of the attack on the plant, it is found that highest number of gallery were identified in the area under the cobs compared to the panicle area, where their number was much lower. The application of insecticides through treatments on vegetation reduced the attack of larvae ensuring the protection of maize plants, the variant treated with the active substance cyantraniliprol 200 g/l registered the lowest attack of 9.4%. In the variants treated with insecticides, the attack had values between 11.6% and 15.4% compared to the untreated variant, which registered an attack of 22.5%. In the period 2017-2020, under the conditions in Central Moldova, the sowing epoch and treatment with insecticides on vegetation significantly influenced the attack, and in terms of cultivated hybrid, the differences were insignificant.