Authors:S. Trdan, L. Milevoj, E. Raspudic, and I. Zezlina
In 2001 Echinothrips americanus Morgan was first recorded in Slovenia. The thrips was first recorded in Europe in 1989, but did not begin to spread to a greater extend until 1993. This polyphagous pest is believed to cause direct damage, especially on the leaves of its host plants. The present contribution describes genetic structure of Echinothrips americanus Morgan rooting in polymorphism of the ITS1-5,8S-ITS2 region of the ribosomal DNA. Echinothrips americanus Morgan is less resistant to insecticides and its ability to inhabit new areas is smaller, compared to the Western flower thrips [Frankliniella occidentalis (Pergande)]. It can be concluded that its economic importance in the future will not reach that of the latter. We gave a detailed description of the species, its geographic distribution, and deal with its host plants as well as bionomics and its potential natural enemies.
Authors:B. Purar, G. Bekavac, Đ. Jocković, É. Toldi Tóth, L. Kálmán, E. Raspudić, and M. Dimitrijević
Corn reddening (CR) was observed for the first time in Serbia in 1957. After that, it occurred periodically, mainly in the region of Banat. In 2002 and 2003, a severe outbreak happened in late July / early August. Initial symptoms were the occurrence of a red-violet color on the leaves, leaf sheaths, husks and the bare portion of internodes. The symptoms typically appeared at the milk maturity stage and the discoloration was the most intensive at top leaves, around the main vein and along the edges, from leaf base to tip. Soon after the occurrence of the symptoms, the affected plants wilted, the foliage dried rapidly, the red pigmentation disappeared for a greater part and finally plant died off. The ears were underdeveloped and gummous and kernels were shriveled and unfilled.Several experiments were conducted to determine a possible connection between CR occurrence and the studied factors. Corn stunt spiroplasma was not identified in the CR-affected plants, and there was no apparent relationship between CR and soil fertility or nematode species identified in soil and plant samples. Insecticide-treated plots had lower CR incidence than untreated (control) plots, indicating that biotic factors could be involved.
Authors:M. Ivezic, J. Tollefson, E. Raspudic, I. Brkic, M. Brmez, and B. Hibbard
The western corn rootworm (
Diabrotica virgifera virgifera
LeConte (WCR)) is a major pest of corn in USA. The pest arrived in Croatia in 1995, and today over 250.000 ha are infested. Insecticides are regularly used to control WCR, but the cost is high, can pose environmental risks, and may become ineffective due to resistance. Growing corn that is resistant to corn rootworms would be a valuable alternative to insecticides. Nine Croatian (Institute of Agriculture, Osijek) and two Pioneer Hi-Bred Int. Inc. (Johnston, Iowa, USA) commercial corn hybrids were evaluated for WCR resistance at two locations using complete randomized block design with four replications. One location was in east Croatia (Osijek) and one was in the USA (Iowa). The hybrids’ tolerance to larval feeding was rated using root injury, root regrowth and root size. Root injury was rated using the Node-Injury Scale 0–3 and evaluation of root size and root regrowth were done by scale 1–6. In an analysis of variance combined across locations, root injury didn’t show any significantly differences among hybrids, but root regrowth and root size were significantly different.