One measure to control wireworms is tillage during or shortly after egg laying by the click beetle. For this purpose, it is important to know the period of egg laying. Within the click beetle monitoring, the flight times of the most important pests are determined by means of specific pheromones. These attract only the male beetles, whose flight cannot necessarily be associated with the time of egg laying. Specific pheromones are also only available for click beetles of the genus Agriotes. In western Lower Austria, however, wireworms of other genera also cause extensive damage to potatoes. The project therefore tested other trap systems, such as adhesive panels and scents. It was found that these trap systems are also essentially unsuitable for catching the female beetles, so new trap systems will be developed in the future.
Click beetles prefer to lay their eggs in densely vegetated, meadow-like areas. The eggs and newly hatched young larvae are sensitive to drought and mechanical influences. Therefore, wireworm control by tillage is most effective during or shortly after egg laying. Knowledge of adult beetle flight times and associated egg laying is therefore critical. Survey of the flight times of the major pest species is usually done using specific pheromones. These attract only the male click beetles. Especially in the case of click beetle species with very long flight phases, the period during which eggs are mainly laid cannot be determined more precisely. Specific pheromones are also only available for beetles of the genus Agriotes. However, wireworms of the genera Melanotus, Selatosomus and Hemicrepidius also cause extensive damage to potatoes in western Lower Austria.
Therefore, one aim of the project was to test currently available trap systems for their suitability to survey the flight phases of female click beetles of different genera. Surveys were conducted at eight sites using kairomon and sticky traps. Sites were selected based on pheromone catches from previous years or wireworm collections. Since the attractiveness of the tested trap types is non-specific, the click beetles in the traps had to be determined. At the 1220 Vienna site (Spargelfeldstraße), a comparison of three trap systems of Csalomon® was made: (1) Yaltor trap with Kairomon (A. ustulatus, bisexual), (2) VARb3 trap with Kairomon (A. ustulatus, bisexual), and (3) yellow panel (PALs). At the remaining seven sites (Breitstetten, Kleinrötz, Wollmannsberg, Großnondorf, Gnadendorf, Niederstrahlbach, and Großhaslau), one Yaltor trap with kairomon (A. ustulatus, bisexual), and one yellow PALs sticky board were installed at each site. The sticky boards and the beetles were subsequently sent to us for identification.
At the 1220 Vienna site in 2021, only click beetles of the species Agriotes ustulatus were captured using all three trap systems tested, with the exception of one specimen of the genus Athous, which was found on a yellow panel. By means of yellow board, a total of 404 click beetles of the species A. ustulatus were caught at the site, 186 of which were weilbliche and 218 male beetles. The trap system Yaltor + Kairomon achieved 288 catches of A. ustulatus, of which 268 were male beetles and 20 were female beetles. The trap system VARb3 + Kairomon achieved a total of 108 catches of A. ustulatus beetles, of which 97 were males and 11 were females.
At the 1220 Vienna site, the yellow board proved to be the most efficient trap for surveying the flight of female click beetles of the species A. ustulatus. At this site, the yellow panel was the only trap system that also captured another click beetle genus, but to a negligible extent. Results indicate that traps currently available for purchase are inadequate for surveying the flight of female click beetles of most Agriotes species and other genera of concern. Therefore, so-called grass-cutting traps will be tested at selected sites in 2022.
Benefit of the project
Wireworms, the larvae of click beetles, cause extensive damage to arable and vegetable crops every year. Rising temperatures and the increase in dry periods accelerate population development and lead to an increase in wireworm damage. At the same time, the "Green Deal" aims to reduce the use of plant protection products by 50% by 2030 and to farm 25% of agricultural land in the EU organically. To achieve these goals, the efficiency of the available mechanical, biological and chemical regulatory measures must be optimized. Knowledge of the biology of the pest species and their specific differences will make a significant contribution to more efficient wireworm regulation in the future.
Last updated: 02.08.2022