Efficiency of insecticide and bioinsecticide treatments against infestation of European corn borer and their effect on maize yield

Abstract

During 2008 and 2009, efficacy of insecticidal products, based on thiamethoxam and imidacloprid, were tested. Furthermore, effects of entomophatogenic fungus Beauveria bassiana on the infestation intensity of European corn borer (Ostrinia nubilalis), were established over effects of both, 10 different treatments of maize seed (8 treatments and 2 controls) and the application of the fungal inoculum. Trials were carried out on maize crop under field conditions in accordance with the EPPO method. Results obtained in the studies with the product Cruiser 350 FS (350g l-1 thiamethoxam) applied in the amount of 0.9 l per 100 kg of seed and the products Imidor 600 FS and Gaucho 600FS (600g l-1 imidacloprid) applied in the amount of 0.7 l per 100 kg of seed, point out to satisfactory efficacy in controlling ECB and satisfactory effects on maize yields. The intensity of ECB infestation, expressed in percentages, ranged from 50.1% to 74.1%. The interrelation between average percentages of infested plants and obtained yields in both investigation years (2008-2009) in Zemun Polje was established. Results over treatments indicate that the highest percentages (62.2%) of infested plants were observed in the control variant (K1- Captan). Moreover, as expected, the lowest yield was also recorded in this variant. The treatment with the fungicide Maxim combined with the insecticide Criuser proved to be the most efficient. At the same time, the percentage of infested plants was the lowest in this treatment (53.32%) and the yield was the highest (8.610 t ha-1). The infestation level of maize plants in this treatment was significantly reduced over years of investigation in comparison with remaining treatments. Meteorological factors during the years of investigation, especially unfavourable agroecological conditions in 2009, affected the average yield of maize per hectare. The yield (8.314 t ha-1) recorded in the treatment with the inoculum of B. basssiana was almost equal to the one recorded in the treatment with the product Cruiser (8.610 t ha-1), while it was higher than the yield obtained in the treatment with the products Gaucho (7.506 t ha-1) and Imidor (8.259 t ha-1) combined with the fungicide Maxim. These differences were not statistically significant. Seed treatments with the fungal inoculum were not significantly different in any of observed parameters, except in the seed treatment with Captan. The comparison of data obtained in the two-year studies (2008-2009) under conditions of natural ECB infestation, shows prevalence of plants with damages of leaves (type H2) and tassels (type M3-4), which is indicated with the average score of 2.43. According to the average scores, it can be concluded that ECB infestation did not result in damages that would have significantly affected maize yield. In order to establish significance of certain observed parameters, they were compared and their correlations were determined. The greatest negative correlation with the 0.05 probability level (r= -0.96533) was established between the plant damage score and the recorded yield. Since recorded value of coefficients of correlation was approximately 1, it can be stated that the complete functional linear dependence existed among variables. Achieved results show efficiency of insecticides based on thiamethoxam and imidacloprid in the regulation of the infestation level in maize and also point to negative effects of the fungus B. bassiana on entomofauna of maize and its mycoinsecticide activity that could find an application in biocontrol of insect pests of maize.

Tokom 2008. i 2009. godine, ispitana je efikasnost insekticidnih preparata, na bazi tiametoksama i imidokloprida i entomopatogeno dejstvo Beauveria bassiana na intenzitet napada kukuruznog plamenca (Ostrinia nubilalis) i njihovog uticaja na prinos srednjestasnog hibrida kukuruza. Ispitivanja su izvedena u skladu sa EPPO metodom u poljskim uslovima u usevu kukuruza. Ostvareni rezultati ispitivanog preparata Cruiser 350 FS (350g l-1 tiametoksama) koji je primenjen u količini 0,9 l na 100 kg semena i preparata Imidor 600 FS i Gaucho 600FS (600g l-1 imidokloprida) primenenjenih u količini 0,7 l na 100 kg semena, ukazuju na zadovoljavajuću efikasnost u suzbijanju kukuruznog plamenca i visinu prinosa kukuruza.