During diapause, a state of temporarily arrested development, insects require low winter temperatures to suppress their metabolism, conserve energy stores and acquire cold hardiness. A warmer winter could, thus, reduce diapause incidence and duration in many species, prematurely deplete their energy reserves and compromise post-diapause fitness. In this study, we investigated the combined effects of thermal stress and the diapause program on the expression of selected genes involved in antioxidant defense and heat shock response in the European corn borer Ostrinia nubilalis. By using qRT-PCR, it has been shown that response to chronic heat stress is characterized by raised mRNA levels of grx and trx, two important genes of the antioxidant defense system, as well as of hsp70 and, somewhat, of hsp90, two major heat shock response proteins. On the other hand, the expression of hsc70, hsp20.4 and hsp20.1 was discontinuous in the latter part of diapause, or was strongly controlled by the diapause program and refractory to heat stress, as was the case for mtn and fer, genes encoding two metal storage proteins crucial for metal ion homeostasis. This is the first time that the effects of high winter temperatures have been assessed on cold-hardy diapausing larvae and pupae of this important corn pest.

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.

High and stabile yield in different production environments is priority in maize breeding. New statistical methods are constantly being sought to accompany analysis of variance, in order to achieve more reliable hybrid assessment. In this study nonparametric stability analysis is applied in order to assess GxE interaction for yield of 36 commercial maize hybrids. The experiment was set up at five locations in Serbia for three years according to the Randomised complete block design in three replications. Yield stability of investigated genotypes was analysed by stability parameters Si (1), Si (2), Si (3), Si (6) TOP and RS. Analysis of variance identified highly significant F values for all experimental factors. Bredenkamp method confirmed the existence of non-crossover GxE interaction, for maize yield. Hybrid ZPH15 achieved the most stable yield based on parameters Si (1) and Si (2). According to parameter Si (3) it was ZPH5, while based on parameter Si (6) it was ZPH34. The highest overall yield achieved ZPH36 (11.18 t ha-1), which was quite unstable (rank 24 in parameters Si (1) and Si (2)), and very unstable (rank 34 in parameters Si (3) and Si (6)). The most stable hybrids had average yields. In total, the hybrid ZPH23 had the best average rank (15.93). Based on TOP parameter, ZPH36 had the best rank (yield), followed by ZPH11, ZPH20, ZPH21 and ZPH9. However, RS parameter revealed that ZPH21 was the most stable hybrid, so taking into account both TOP and RS parameters this is the most productive and the most stable hybrid. Based on this research, TOP and RS are the best parameters for selecting new maize hybrids for production in particular environment. In case of identical TOP value, the genotype with the lowest RS value should be selected. The parameters Si (1), Si (2), Si (3) and Si (6) can be used as alternative methods for the selection of genotypes with moderate yield and high stability.

The backbone of modern technologies is the creation of tolerant genotypes at the ECB with special emphasis on the interaction between the degree of plant damage and metabolic processes as potential responses to stress. During the vegetation period of 2016 and 2018, the variability and response of four maize genotypes to the effectiveness of insecticides and bioinsecticides and the interdependence with the dynamics of the ECB population were examined. Out of a total of 11,023 attacked plants in both years of the survey, in 2016 the largest number of plants (4,841) with a broken stalk above the ear and at the height of the ear and belonged to categories C3 to C8. In 2018, there was no damage to the tassel and ear, while 3,672 plants were dominated by leaf damage and perforation in the H2 type. In addition to the fact that more infested plants were observed in the genotypes, ZP 434 and ZP 666 the categories of damage type C5, C6 and C7 were more pronounced. The foliar treatment of plants with chlorantraniliprole in two-year research proved to be the most effective with the least number of attacked plants with a high degree of damage. In contrast, bioinsecticide treatment of plants, in addition to a large number of infested plants, was dominated by high categories of damage that deviated from all other treatments as well as from control. Within the definition of the degree of tolerance of maize genotypes, the influence of treatment on changes in secondary metabolites (phytins) in seeds was observed. It was noticed that there is a trend of positive correlation between the amount of phytin in the seed (mg g-1) with the attack of moths of the first generation and the number of dissected larvae, as well as a trend of negative correlation with the percentage of attacks of the second generation. Correlation coefficients are expressed: in the genotype ZP-600, while in the genotype ZP-666 correlation is the lowest, ie. irrelev?nt. The obtained results may be of great importance in future work aimed at the selection of maize genotypes tolerant and resistant to corn borer attack, connected to the role of phytin, as an antioxidant and phosphorus deposited in corn grain.

Western corn rootworm (WCR) (Diabrotica virgifera virgifera LeConte) is one of the most important and potentially most dangerous pests of maize. Since its occurrence in Serbia in 1992, it has been present in almost all areas under maize cultivation. Alongside with all preventive measures, first of all, the crop rotation, which is considered the most economic one, a great attention has been paid to the forecast of the pest occurrence based on the flight dynamics and the population level. The flight dynamics, sex dominance, variations in the population level depending on the trap types and climate factors were observed on two locations: Crepaja in three-year continuous cropping (2005-2007) and in the experimental field of the Maize Research Institute, Zemun Polje in the duration of five years (2005-2009). According to the flight dynamics of WCR adults, the highest population level of this pest was observed in 2005, while the comparison of the number of adults over locations showed greater abundance of the pest in Crepaja than in Zemun Polje, which was attributed to extreme favourability of agro-ecological conditions on this location for the WCR development. The 2008-2009 period was characterised by the reduced number of WCR, which coincided with the extremely arid conditions that do not favour the development of this pest.

Soybean (Glycine max L.) is a major source of plant proteins, but its use is restricted by anti-nutritional factors such as the Kunitz trypsin inhibitor (KTI). Eliminating KTI improves protein digestibility and reduces processing costs in food and feed production. This study aimed to use simple sequence repeat (SSR) markers in marker-assisted selection (MAS) for KTI-free soybean genotypes developed at the Maize Research Institute ?Zemun Polje? (MRIZP). The new breeding line L003, derived from a cross between the standard line L584 and the KTI-free cultivar ?Laura,? was analyzed. Fifty-two F? seeds were screened with SSR markers Satt228 and Satt409, and the observed results were validated by detecting possible KTI protein by polyacrylamide gel electrophoresis (PAGE). In all L003 plants, homozygosity for the KTI-null genotype was observed by both SSR markers. Biochemical analysis showed the absence of the 21.5 kDa KTi protein band in L003, while the control genotype ?Lidija? with the dominant allele (TiTi) expressed KTI. Those results demonstrate a strong correlation between SSR marker profiles and the presence of KTI protein. Our results showed that both Satt228 and Satt409 are reliable tools for foreground selection in MAS, supporting the efficient development of KTI-free soybean cultivars. These results promote breeding strategies to develop nutritionally improved soybean varieties for food and feed industries without the necessity of thermal inactivating KTI.