Testing the Efficiency of the Push-and-Pull Strategy during Severe Ips typographus Outbreak and Extreme Drought in Norway Spruce Stands

Abstract

Protection of Norway spruce stands using anti-attractants was tested during an outbreak of bark beetles (Ips typographus) in their spring flight. The aims of this study were as follows: (1) to test the proposed experimental design for tree protection; (2) to evaluate height-specific alternatives for dispenser installation on trees; and (3) to evaluate the efficiency of tree protection measures using anti-attractants under bark beetle infestation and drought stress. The experiment was conducted at the forest edges adjacent to recent clearcuts on 10 blocks in the eastern Czech Republic. Each block had three adjacent experimental areas, with 20 trees growing in two rows at the recently cut forest edge (10 trees per row). In front of a block in each of the three areas, four pheromone traps were installed. The treatment area was protected by anti-attractants. The second area served as a so-called switch area, where beetles from the treatment area, as the outflux redirected from the anti-attractant, would start new attacks if not caught in nearby pheromone traps. The third area was a control. We attached anti-attractant tube dispensers on each tree trunk of the treated area at two heights. The results suggest a redirecting effect of anti-attractants, pushing beetles into the switch area and causing subsequent attacks, which was greater than in areas containing treated trees. There was no difference between two dispensers placed at 1 and 8 m height and both at 1 m. A switching effect of beetle attacks occurring outside of the treated areas was observed. Mounting anti-attractant dispensers on tree trunks at one low position above the ground can be substantially less labour-intensive and as efficient as positioning them at two different heights. For areas affected by severe drought and extremely dense bark beetle populations, the use of anti-attractants did not prove effective.

Field application of tea volatiles mediating host selection of Aleurocanthus spiniferus

“…Previous studies have shown that when populations were low, enlarging the entry area can increased Drosophila suzukii captures and improved selectivity for D. suzukii (Renkema et al 2014). When areas affected by extremely dense bark beetle populations, the use of antiattractants did not prove effective (Jakuš et al 2022). Suggesting that population density must be taken into account in the testing of attractant effects.…”

Field effects of oxygenated monoterpenes and estragole combined with pheromone on attraction of Ips typographus and its natural enemies

“…Both the push and pull might be enhanced by the addition of new semiochemicals (Jakuš et al, 2022;Deganutti et al, 2023). The addition of (+)-isopinocamphone to the trapping lure could increase beetle attraction away from trees while simultaneously protecting them from an estragole-enhanced beetle repellant.…”

“…Aggregation pheromone components, produced by male beetles after successful colonization (Birgersson et al, 1984;Ramakrishnan et al, 2022), have been employed for monitoring and controlling I. typographus populations (Heber et al, 2021). Furthermore, recent research has focused on the management potential of kairomones, compounds originating from both host spruce trees and non-host trees, e.g., broadleaf trees (Zhang and Schlyter, 2004;Jakuš et al, 2022). Bark beetles possess a sophisticated olfactory system that enables them to detect and distinguish the chemical composition and quantity of these odors (Andersson, 2012).…”

“…Both compounds demonstrated a similar level of dose-dependent anti-attractant activity, with trans-4-thujanol inhibiting more the captures of females than males (Jirošová et al, 2022b). These compounds have been tested in combination with other anti-attractants for the protection of spruce trees in various forest environments, such as fresh forest edges or fragmented forests (Jakuš et al, 2022;Jirošová et al, 2022a). Furthermore, individual compounds trans-4-thujanol, (+)-isopinocamphone, camphor, and terpinen-4-ol were tested in different doses in two-choice Petri dish walking laboratory tests to assess their attractiveness to I. typographus.…”

Spruce Protection against Ips typographus with Anti-Attractant Blend of Tree-Based Semiochemicals: From Small Experimental Plots to Stand Scales

“…The reduction by anti-attractants on bark beetle-induced tree mortality has been observed in mountainous or boreal landscapes under normal weather conditions [20][21][22]32]. However, in conditions of spruce monocultures in low elevation under drought stress and a high bark beetle population, anti-attractants were not effective [33]. Studies involved the use of dispensers comprising verbenone [20,32] or a blend consisting of verbenone, conophthorin, and GLVs [20][21][22].…”