Recent European Union regulations aim at reducing the use of chemical pesticides in agriculture. In sunflower production in Serbia, the use of synthetic insecticides for soil and seed treatments has become a prevailing practice for wireworm (Coleoptera: Elateridae) control. However, a number of compounds efficiently used as seed treatments have been phased out. This work aimed at assessing the potential of an environmentally friendly “Attract and Kill” strategy (A&K) for controlling wireworms in sunflower in comparison to conventional insecticides. The experiments were carried out in 2018, 2019 and 2021 involving (a) soil treatments with ATTRACAP® and a Force 1.5 G; (b) seed treatments with Sonido, Force 20 CS, Lumiposa and Buteo Start 480 FS; (c) controls (i.e., untreated seeds). The efficacy of the treatments was assessed based on the plant density and emerging plant damage (%). A damage rating scale (levels 0–5) was created, aiming for a more reliable and concrete interpretation of the results. Data were processed using binomial and multinomial regressions, followed by modelling of the damage and calculating the odds of damage occurrence, depending on the applied insecticide. In all experimental years and at all localities, the Force 20 CS and/or Force 1.5 G treatments resulted in the highest plant density and the lowest percentage of plant damage. ATTRACAP® showed good effectiveness, since plant density and percentage of damaged plants were at the same level of significance as the commonly used conventional insecticides in sunflower production (Sonido for seed treatment and Force 1.5 G for soil treatment). Thus, the A&K strategy was efficient in controlling wireworms at conditions of low abundance, based on three-year experimental results. Although the damage rating scale enabled a clear differentiation of plant damage caused by wireworms responsible for reduced plant density, more reliable models were obtained by binomial regressions, classifying plants as damaged or undamaged.
Drought stress during the reproductive phase of sunflower can significantly reduce achene yield by affecting inflorescence size, nectar quality, and pollinator activity. This study aimed to analyze the morphological characteristics of the reproductive region, quantify nectar sugar components, and evaluate pollinator presence and pollination success in wild Helianthus species as an important genetic resource for breeding cultivated sunflowers under drought conditions. Morphological investigations were conducted during the flowering and achene development phases with a stereo microscope and calipers. Nectar sugar concentrations were analyzed via HPLC, and pollinator presence was monitored twice a week for two months. This study highlights the correlation between evaluated traits, emphasizing their importance as yield indicators. Significant differences were observed in reproductive characters, nectar quality, and pollination success among the species. Helianthus annuus and Helianthus argophyllus exhibited superior reproductive performance with high nectar sugar concentrations and larger inflorescences, enabling successful pollination and higher achene yield. In contrast, Helianthus debilis demonstrated lower reproductive efficiency, with a higher percentage of empty achenes. These findings provide valuable insights for breeding programs, highlighting H. argophyllus and H. annuus as promising genetic resources for developing sunflower genotypes with increased yield and improved floral traits adapted to drought conditions.
Maize (Zea mays L.) is one of the most important agricultural crops in the world; however, its production is often threatened by several harmful insects, one of which is the European corn borer, Ostrinia nubilalis (Hübner). This study aimed to examine the efficacy of several biological control methods against this pest. A randomized block design was used in the study, which included three treatments: parasitic wasps (Trichogramma brassicae), common green lacewings (Chrysoperla carnea), a combination of both agents and a control. The results showed that the treatment with T. brassicae wasps, as well as their combination with C. carnea predators, significantly improved the maize grain yield over the control treatment. The same combined treatment significantly improved the yield over treatments with only Trichogramma and only C. carnea predators, suggesting a higher efficacy of the combination of both agents in improving grain yield. Fewer tunnels and larvae in stalks, compared to other treatments, including the control, were also observed in this treatment. The reduced number of tunnels and larvae in stalks directly enabled plants to allocate more resources into grain development, which contributed to improved grain yield. In light of the growing focus on minimizing insecticide applications to mitigate environmental impacts, a combination of parasitic wasp and lacewings predator could be a suitable biological alternative to the use of chemical insecticides.