P. STRBAC, T. KERESI
Faculty of Agriculture, Novi Sad, Yugoslavia
V. PECARSKI
Agricultural Productive Institute “Sokolac”, Novi Becej, Yu

Since its first occurrence, until now, Western Corn Rootworm (Diabrotica virgifera virgifera Le Conte) has spread quickly, first in the main maize growing area of Yugoslavia, and then in other parts of country. This pest has tendency of further spreading, occupying first of all neighboring countries, followed by some European ones, whose ecological conditions favor to its reproduction and development.

With the aim to prevent economical losses, different sampling techniques and programs have been developed for all stages of corn rootworm. Imagoes sampling, i.e. plant  inspection for damage prediction represents a standard method.

Trap use has advantages, for population assumption is done in longer time period, whereas during plant inspection it is performed in definite terms only, with the risk of being subjective. By trap use need for well-educated specialists for inspection of whole plants is eliminated. However, opinions on efficiency and credibility of different trap use are divided.
From the given reasons, during 2001, in the region of mid Banat (Yu), in hybrid fields of different ripening groups (NS 680, NS 644, NS 599 and NS 420), USA yellow sticky traps (“Pherocon AM” and “Multigard”) and Hungarian pheromone trap were tested. Traps were set up on July 18, and the last reading was on September 5. Trap assessment and visual assessment of plants was performed weekly.

The greatest occurrence of WCR adults was during August in all hybrids, after which population kept reducing. The greatest total imagoes number was caught in the field of the hybrid NS 599. Hybrids NS 680 and NS 640 had similar imagoes number, whereas the smallest population was in the field of the hybrid NS 420. Among different traps have been determined significant differences in catch. The highest catch was on pheromone, similarly lower on yellow “Pherocon AM” and “Multigard” trap, with somewhat lower catch by visual assessment. These differences among applied traps and methods are evident in all studied hybrids.

The results should be considered preliminary ones. In the following year studies will continue and probably be completed by data on larvae density and harmfulness, as well as by the number of adults in emergence cages.