The identification and description of the chemical signals involved in the aggregation of bark beetles may lead to the development of integrated pest management strategies using synthetic pheromones. Ips sexdentatus Boern. (Col.: Scolytinae) colonizes trees of the Pinus genus across Europe, causing severe damage in occasions. The effect of cis‐verbenol, ipsenol, 2‐methyl‐3‐buten‐2‐ol (MB) and myrtenol in relation to the major pheromonal compound ipsdienol on the aggregation behaviour of I. sexdentatus was studied on four field bioassays. The ternary blend of racemic ipsdienol, cis‐verbenol and racemic ipsenol consistently caught the highest number of bark beetles, resulting in large standardized mean differences (dunbiased > 0.8). The binary blends between ipsdienol and ipsenol, and ipsdienol and cis‐verbenol also improved the performance of ipsdienol, although only ipsenol did it significantly. On the other hand, catches were reduced (dunbiased = −0.96) when MB was released along ipsdienol, although the effect was found to be non‐significant. On a third bioassay, the relative release rates between ipsdienol, ipsenol and cis‐verbenol were studied. Although no differences were found between the ternary blends, a ratio of 1 : 0.25 : 0.5 for ipsdienol, ipsenol and cis‐verbenol, respectively, scored the strongest effect size (dunbiased = 1.17). A fourth bioassay studied the behavioural effects of myrtenol and found no significant modifications to previously established findings. Myrtenol on its own attracted almost no individuals of I. sexdentatus. High numbers of bark beetle predators Thanasimus formicarius L. and Temnochila caerulea Olivier were trapped during the trials. The binary blend between ipsdienol and ipsdienol was shown to catch the highest significant amount of T. formicarius, whereas numbers of T. caerulea caught were highest on the binary blend between cis‐verbenol and ipsdienol. Presented results establish the ternary blend between ipsdienol, ipsenol and cis‐verbenol as a reference functional aggregative lure ready to be used on the management of I. sexdentatus.

The pine sawyer beetle Monochamus galloprovincialis, a secondary pest of pines in Europe and North Africa, has become important as it was identified as the vector in Europe of Bursaphelenchus xylophilus, the causal agent of pine wilt disease (PWD). An effective trapping system is needed, not only for monitoring the insect vector but also for direct control of its population. Trapping may also provide key information on the nematode load carried by the beetles, allowing early detection of infections, provided that captured beetles remain alive within the trap. Highly effective attractants have been developed in recent years that are commonly used in combination with diverse standard trap designs. In this study, several trap designs were developed and compared to commercial standard models in order to determine which designs maximized the number of attracted insects actually caught and the proportion of them remaining alive. In total, 12 trap designs were evaluated in five field experiments carried out in France, Spain and Portugal. Teflon coating applied to the whole trap and extended, ventilated collecting cups resulted in a significant improvement of trap performance. These modifications led to significant increases of pine sawyer catches, up to 275%, when applied to multiple‐funnel or black cross‐vane traps, compared to standard designs. Furthermore, a significant proportion of the captured beetles remained alive within the trap. These findings have been used to develop new commercial traps (Econex Multifunnel‐12® and Crosstrap®; Econex, Murcia, Spain) available to forest managers. A model for insect survival within the trap was also fitted. Elapsed time between consecutive samplings, mean relative humidity and maximum radiation were the three most significant variables. Thus, traps should provide a suitable sample of live insects if sun exposure of the trap is minimized and a reasonable sampling schedule is implemented.

1 Thanasimus formicarius and Temnochila caerulea, two of the main predators of Ips sexdentatus, a well-known forest pest in Southern Europe, are captured in high numbers when trapping I. sexdentatus as a result of the kairomonal effect of the lures used. 2 A preliminary field trial showed that predators could survive for at least 1 week within trapping containers, although predator mutilation and high predator death rates were observed. 3 Different modifications of conventional multiple funnel and slot traps with the objective of reducing natural enemy entrance into trap containers were bioassayed in field experiments conducted over four seasons. Based on the larger sizes of predators, different designs using welded wire-mesh screens improved performance to different extents. Providing escape windows just above the screen on multiple funnel traps gave the most promising results, including when effect sizes among all tested designs were compared. 4 Thus, a simple modification of the lowest funnel of the multiple funnel traps would reduce the bycatch of T. formicarius and T. caerulea, hence improving the efficiency of trapping programmes by lowering the likely impact on natural populations of these predators.

Verbenone and trans‐conophthorin were tested against the aggregation pheromone of the six‐toothed bark beetle (Ips sexdentatus Boern.) on two trapping bioassays. Two different release rates of verbenone (2 mg/24 h and 40 mg/24 h) gave similar significant catch reductions (by 73% and 82%, respectively), whereas trans‐conophthorin lowered the catch by 45%. Joint release of both compounds reduced trap catches by 90%. Furthermore, the effect of these semiochemicals on Thanasimus formicarius L. and Temnoscheila coerulea Olivier, two important natural enemies of I. sexdentatus, as well as Hylurgus ligniperda Fabricius, a native associated scolytid, was evaluated. Both predators were significantly affected by verbenone, whereas the effect on H. ligniperda could not be concluded. Based on these results, verbenone was used in a third experiment to protect standing healthy Pinus nigra salzmannii J. F. Arnold trees from induced I. sexdentatus attack. The experiment consisted of two treatments and 20 paired‐tree replicates. Treatments were pheromone‐baited control trees and baited trees treated with verbenone (60 mg/24 h). These trees served as centres of 10 m radius plots from where a number of plot variables was recorded for local stand description. After the experimental period, all control trees had suffered attacks by I. sexdentatus, whereas trees treated with verbenone were significantly less attacked. Among other stand variables considered in the study, the following characterized the variation among plots most efficiently: (i) plot density, (ii) dominant height and (iii) the proportion of suppressed or (iv) intermediate dominance level trees in the plot. However, these variables did not significantly affect the repellent effect by verbenone. Further research should evaluate the use of verbenone on management strategies of ongoing attacks of I. sexdentatus.

Some bark beetle species (Coleoptera: Scolytinae) produce aggregation pheromones that allow coordinated attack on their conifer hosts. As a new saproxylic habitat is founded, an assemblage of associated beetles kairomonally respond to bark beetle infochemicals. Ips sexdentatus is one of the major damaging insects of Pinus spp. in Southern Europe. Its response to varying ipsenol (Ie) percentages in relation to ipsdienol (Id) was studied in northwestern Spain, along with the entire saproxylic beetle assemblage captured at multiple-funnel traps. Response profile modeling was undertaken for I. sexdentatus sexes and sex-ratios, associated species and for selected trophic groups using a reference Gaussian model. In addition, the effects on the saproxylic assemblages were analyzed. I. sexdentatus response curve peaked at 22.7% Ie content, while remaining taxa that could be modeled, peaked above ca. 40% Ie. Predator guilds showed a linear relationship with Ie proportion, while competitors showed a delayed response peak. Consequently, species assemblages differed markedly between varying pheromone component mixtures. Given that the evaluated pheromonal proportions mimicked that of logs being colonized by I. sexdentatus, results suggested that the registered differential responses at different levels might provide I. sexdentatus with a temporal window that maximizes conspecific attraction while reducing interference with competitor and predatory guilds. Described responses might help improve the monitoring of the population status of target bark beetles and their associates, but also point toward the by-catch of many natural enemies, as well as rare saproxylic beetle species, interfering with the aims of sustainable forest management.

The spread of the pine wood nematode (PWN), Bursaphelenchus xylophylus (Nematoda; Aphelenchoididae), the causal agent of the pine wilt disease, is greatly constrained to the dispersal of its vectors, long‐horned beetles of the Monochamus genus. Disease spread at global and regional scales has been mainly caused by human‐mediated transport, yet at a local scale, the short‐ and long‐distance dispersal behaviour of the beetles determine colonization dynamics. Three mark–release–recapture experiments using commercial traps and lures allowed the parameterization of the dispersal kernel under two landscape fragmentation scenarios for the only known European PWN vector, Monochamus galloprovincialis. The respective release of 171 and 353 laboratory‐reared beetles in continuous pine stands in 2009 and 2010 resulted in 36% and 28% recapture rates, yet, at a fragmented landscape in 2011, only 2% of the released 473 individuals could be recaptured. Recaptures occurred as soon as 7–14 days after their release, in agreement with the requirement of sexual maturation to respond to the pheromone–kairomone attractants. Data from the first two experiments were fitted to one mechanical and two empirical dispersal models, from which the distance dispersal kernels could be computed. Derived estimated radii enclosing 50% and 99% of dispersing M. galloprovincialis under continuous pine stands ranged between 250–532 m and 2344–3495 m depending on the replicate and choice of model. Forecasted recaptures in 2011 resulted in a moderate underestimation of long‐distance dispersal, probably influenced by the high degree of habitat fragmentation. In addition, trapping parameters such as the effective sampling area (0.57–0.76 ha) or the seasonal sampling range (426–645 m) could be derived. Observed results, derived dispersal kernels and trapping parameters provide valuable information for the integrated pest management of PWD. Furthermore, estimated dispersal distances indicate that ongoing clear‐cut measures for eradication in the European Union are likely ineffective in stopping the vectors dispersal.

Monochamus galloprovincialis Olivier beetles vector the causal agent of pine wilt disease (PWD), nematode Bursaphelenchus xylophilus (Steiner and B€ uhrer) Nickle, in Europe. Traps and attractants have been optimized for the capture of M. galloprovincialis, increasing the possibility of developing methods of lowering its population in PWD-affected areas with the aim of either eradicating the disease or containing the spread of it. To evaluate the effectiveness of such mass-trapping campaigns, two sets of experiments were carried out in 2010 and 2013. The release of 353 laboratoryreared beetles in the experimental area of 2010 facilitated the evaluation of capture-mark-recapture (CMR) procedures in the calculation of population abundance estimates using the POPAN formulation of the Jolly-Seber model, a prerequisite for the assessment of mass trapping. Abundance estimates derived from best-fitting parameters fell within one standard error of the real figures, proving the method appropriate. In 2013, four trap densities were tested in six 36 ha plots. To evaluate the removed proportions, the local beetle population was estimated in a contiguous 260 ha study area. A superpopulation of 21 319 individuals could be calculated from the CMR data, corresponding to a rough density of 82 individuals per hectare. Evaluated trapping densities removed 4.66%, 20.50%, 33.33% and 59.80% of M. galloprovincialis population at 0.02, 0.11, 0.25 and 0.44 traps/ha, respectively, thus the estimated 95% removal would occur at 0.82 traps/ha. These results suggest that substantial reduction of M. galloprovincialis abundances might be achieved via mass trapping and that this represents a very promising management method for the containment or eventual eradication of B. xylophilus at the areas affected by the PWD.

Transmission of the causing agent of the pine wilt disease, Bursaphelenchus xylophilus (Steiner & Buhrer) (Nematoda: Aphelenchoididae), among Pinus pinaster Aiton (Pinaceae) trees in Portugal is known to occur during pine sawyer, Monochamus galloprovincialis (Olivier) (Coleoptera: Cerambycidae), adult feeding on twigs of healthy trees or during female oviposition on dying or dead trees. Still, the disease does not affect the other potentially susceptible local pine species, Pinus pinea L. Several experiments evaluated the suitability of P. pinea as a host for M. galloprovincialis feeding, oviposition, and progeny development. Feeding responses were studied in two-choice experiments pairing P. pinea twigs with P. pinaster, Pinus halepensis Miller, Pinus sylvestris L., Pinus uncinata Miller, and Pinus nigra Arnold. Another test assessed the effect of increased dosages of limonene applied to P. pinaster twigs on M. galloprovincialis feeding. Oviposition preferences for P. pinaster, with either intact or manipulated bark thickness, P. pinea, and P. sylvestris were also studied in two-choice tests. Finally, suitability of P. pinea as a substrate for the development of M. galloprovincialis offspring was tested. Results showed that P. pinea could be an acceptable host for the pine sawyer feeding under laboratory conditions. Only P. sylvestris and P. pinaster twigs were significantly more consumed than those from P. pinea. Control and limonene-treated twigs were eaten similarly, but feeding decreased as dose increased, suggesting an inhibitory effect of limonene. Oviposition wounds, both eggcontaining and eggless, occurred more on P. pinea than on P. sylvestris or P. pinaster, though the percentages of wounds indicating successful egg laying were significantly higher on P. pinaster and P. sylvestris. Monochamus galloprovincialis progeny completed its development on P. pinea, but emergence was lower than on P. sylvestris, likely due to higher mortality during egg and early larval stages. Thus, results on vector host preferences do not explain the observed absence of nematodekilled P. pinea trees in the field.