Kevin J. Dodds

Sirex noctilio in North America: the effect of stem-injection timing on the attractiveness and suitability of trap trees.

1 Sirex noctilio Fabricius, an invasive woodwasp responsible for severe economic damage to pine industries in the southern hemisphere, is now established in the northeastern U.S.A. and portions of eastern Canada. 2 Parts of North America are considered to be high risk for S. noctilio invasion. Effective detection tools, including trap trees, are needed to monitor and survey S. noctilio populations. 3 The present study was conducted to determine the optimal time to chemically stress a tree when aiming to attract the most S. noctilio to the host substrate, as well as to determine which timing produced the most adult progeny. Both of these measures (host attraction and host suitability for development) support the main objectives of the study by offering improved methods for monitoring and management of S. noctilio. 4 Red pine (Pinus resinosa) and Scots pine (Pinus sylvestris) were treated with Dicamba at three time intervals. Multiple funnel lindgren traps were placed on these trees and, at the end of the flight season, the treatment trees were felled and brought into the laboratory. The number of S. noctilio caught in the traps (host attraction) and the number of S. noctilio emerged from the treated trees (host suitability) were determined. 5 Optimal timing of the chemical girdle was dependent on host species. Significantly more female S. noctilio were captured on trap trees prepared 1 month before flight (red pine and Scots pine) or prepared at flight (Scots pine) compared with other treatments. There were also significantly more females reared from Scots pine trap trees prepared at flight and red pine trap trees prepared 1 month before and/or at flight. 6 By the beginning of August, most (79%) of the S. noctilio for the flight season were caught in the traps at the trap trees. The sex ratio (males : females) was closer to 1 : 1 than previously reported in studies from other countries. 7 The results obtained in the present study demonstrate that timing is important when creating a trap tree with herbicide in North America, whether for the purpose of detection or as part of a biological control effort.

Sirex, Surveys and Management: Challenges of having Sirex noctilio in North America

Since 2004, when the Sirex woodwasp, Sirex noctilio, was first discovered in North America, there have been intensive efforts to survey and determine the area infested and to assess management options. In this chapter we review the history of survey efforts in Canada and the USA from 2005 to 2009 and the challenges facing these surveys. Next we describe the significant differences between North America and the Southern Hemisphere (where this insect is a serious pest) in forest types, natural disturbance regimes, competing insects and disease, and forest management methods and how they affect surveys and management. We review the logistical issues of landscape and forest diversity, ownership, and access that affect the implementation of surveys, and biological issues of native siricids and other associated insects and diseases that complicate the use of trap trees and traps. We discuss the challenges of using silviculture and biological methods in North America to control S. noctilio. We conclude that management of S. noctilio will not be easy and must be multifaceted. The diversity, heterogeneity and complexity of North America’s natural forests in terms of natural enemies and competing insects and diseases, may be a problem for survey efforts, but also a solution for management. Finally, the situation in North America is unique, allowing many interesting questions on invasion biology, community ecology, and management of an invasive species in native pine communities to be addressed.

Trap Type, Lure Placement, and Habitat Effects on Cerambycidae and Scolytinae (Coleoptera) Catches in the Northeastern United States

ABSTRACT Semiochemical-based exotic species surveys targeting forest Coleoptera have gradually expanded in North America and elsewhere. Determining how various factors affect trap catches and increase species richness in traps is important for maximizing the efficacy of survey efforts. Studies were conducted in southern Maine and New Hampshire by using ethanol and &agr;-pinene as lures to determine the influence of trap type, lure placement and size, and habitat type on catches of Scolytinae and Cerambycidae in coniferous forests. Three trap types (canopy malaise, intercept panel, and multiple-funnel), three lure placements/sizes (standard placement, above trap, and enlarged), and two habitat types (margins of clearcuts and shelterwood) were tested in three experiments. The three trap types performed equally well in terms of average number of species captured, but the canopy malaise caught more unique species than the other traps. In most cases, traps with lures placed above traps caught fewer beetles than lures hanging from the side of traps or with an expanded surface area. Generally, more insects were captured in shelterwood treatments versus the margins of clearcuts.

Test of Nonhost Angiosperm Volatiles and Verbenone to Protect Trap Trees for Sirex noctilio (Hymenoptera: Siricidae) From Attacks by Bark Beetles (Coleoptera: Scolytidae) in the Northeastern United States

ABSTRACT Sirex noctilio F. (Hymenoptera: Siricidae) is an invasive woodwasp, currently established in northeastern North America. In other regions of the world, stressed trap trees are used to monitor populations of S. noctilio and to provide inoculation points for the biological control nematode Deladenus siricidicola Bedding. However, the operational use of trap trees for S. noctilio in North America may be compromised by the large community of native organisms that inhabit stressed and dying pine trees. Common bark beetles such as Ips pini (Say) and Ips grandicollis (Eichhoff) (Coleoptera: Scolytidae) could potentially compete with S. noctilio and associates for resources on trap trees, possibly reducing the efficacy of trap trees as habitats for the woodwasp. In an attempt to develop a technology to mitigate this potential issue, three common semiochemical interruptants—conophthorin, green leaf volatile mix, and verbenone—were tested for effectiveness in reducing arrivals of I. pini and I. grandicollis on trap trees treated with herbicides in northeastern United States. In addition, the effects of these compounds were determined independently with pheromone-baited multiplefunnel traps. None of the interruptants reduced numbers of I. pini or I. grandicollis either arriving on trap trees or caught in pheromone-baited traps. However, verbenone increased catches of I. grandicollis in traps baited with its pheromone, ipsenol. The mix of green leaf volatiles reduced catches of a native ambrosia beetle, Gnathotrichus materiarius (Fitch), whereas verbenone reduced trap catches of an exotic ambrosia beetle, Xylosandrus germanas (Blandford). Catches of X. gennanus in traps adjacent to trap trees were enhanced with conophthorin.

Trap Lure Blend of Pine Volatiles and Bark Beetle Pheromones for Monochamus spp. (Coleoptera: Cerambycidae) in Pine Forests of Canada and the United States

ABSTRACT In 2007–2008, we examined the flight responses of Monochamus titillator (F.) complex [M. titillator, Monochamus carolinensis (Olivier), and any possible hybrids], Monochamus scutellatus (Say), Monochamus clamator (LeConte), Monochamus obtusus Casey, and Monochamus mutator LeConte (Coleoptera: Cerambycidae) to multiple-funnel traps baited with and without host volatiles and bark beetle pheromones. Experiments were conducted in mature pine (Pinus) stands in Alberta (Canada), and Arkansas, Arizona, California, Florida, Idaho, Michigan, Montana, New Hampshire, North Carolina, Ohio, Oregon, Tennessee, Utah, and Wisconsin (United States). At each location, traps were deployed in 10 replicate blocks of four traps per block. The trap treatments were: 1 ) blank control; 2) ipsenol and ipsdienol; 3) ethanol and &agr;-pinene; and 4) a quaternary blend of ipsenol, ipsdienol, ethanol, and &agr;-pinene. All five species or species complex of Monochamus preferred traps baited with the quaternary blend over all other treatments. The consistency of these results across such a large geographic area suggests that similar selection pressures may be acting on Monochamus spp. in pine forests, regardless of variation in stand composition and climatic conditions. Our results suggest that multiple-funnel traps baited with the quaternary blend of ipsenol, ipsdienol, ethanol, and &agr;-pinene may be highly effective for monitoring various Monochamus spp. in pine forests of North America, and may have utility in trapping and detection programs in North America and overseas.

Considering species richness and rarity when selecting optimal survey traps: comparisons of semiochemical baited flight intercept traps for Cerambycidae in eastern North America

We compared standard multiple‐funnel, modified multiple‐funnel, intercept panel and canopy malaise (SLAM) traps with top and bottom collecting cups for their effectiveness (species richness, rarity, abundance) at capturing Cerambycidae in eastern North America. Experiments were conducted in New York, Louisiana, Massachusetts and Georgia in 2011 and 2012. A combination of pheromones and host volatiles chosen to match local forest types were used as lures. Species richness tended to be higher in SLAM and modified funnel traps than standard funnel and intercept panel traps. SLAM traps also captured the highest number of species, unique species, rare (species accounting for ≤ 1% of total cerambycids at a site) and singleton species at each site. Individual‐based rarefaction and sample‐based species accumulation curves suggested that SLAM traps are more effective for capturing cerambycid species. For many estimates, modified funnel and funnel traps were lower than SLAM traps but greater than intercept panel traps for describing cerambycid communities. Modified funnel and SLAM traps generally captured the highest abundance of cerambycids but the response of the individual subfamily and species varied by trap type. SLAM traps should be considered as a strong tool to describe cerambycid communities when used in conjunction with pheromones and host volatiles.

Effects of Habitat Type and Trap Placement on Captures of Bark (Coleoptera: Scolytidae) and Longhorned (Coleoptera: Cerambycidae) Beetles in Semiochemical-Baited Traps

ABSTRACT Two studies were conducted to determine the effect of habitat selection and trap placement on catches of Scolytidae and Cerambycidae (Coleoptera) in northeastern U.S. forests. In a nonreplicated case study, four habitat types—closed canopy hardwood stand, closed canopy conifer stand, a low-intensity thinned Pinus strobus L. stand, and a high-intensity thinned P. strobus stand—were surveyed using &agr;-pinene, ethanol, ipsenol, ipsdienol, and lanierone. Average trap catches, species richness, and the number of unique species captured were all highest in at least one of the thinned habitats. A second experiment that was replicated evaluated the placement of traps in relation to habitat patches. Semiochemical-baited traps (&agr;-pinene and ethanol) were placed under a closed canopy forest, along an edge, and in a clearing and tested for effects on Scolytidae and Cerambycidae trap catches. Abundance and species richness were generally higher in the closed canopy and edge placements compared with traps in the open area. The highest number of unique species were captured in the edge and clearing.

Considering species richness and rarity when selecting optimal survey traps: comparison of semiochecmial baited flight intercept traps for Cerambycidae in eastern North America

We compared standard multiple‐funnel, modified multiple‐funnel, intercept panel and canopy malaise (SLAM) traps with top and bottom collecting cups for their effectiveness (species richness, rarity, abundance) at capturing Cerambycidae in eastern North America. Experiments were conducted in New York, Louisiana, Massachusetts and Georgia in 2011 and 2012. A combination of pheromones and host volatiles chosen to match local forest types were used as lures. Species richness tended to be higher in SLAM and modified funnel traps than standard funnel and intercept panel traps. SLAM traps also captured the highest number of species, unique species, rare (species accounting for ≤ 1% of total cerambycids at a site) and singleton species at each site. Individual‐based rarefaction and sample‐based species accumulation curves suggested that SLAM traps are more effective for capturing cerambycid species. For many estimates, modified funnel and funnel traps were lower than SLAM traps but greater than intercept panel traps for describing cerambycid communities. Modified funnel and SLAM traps generally captured the highest abundance of cerambycids but the response of the individual subfamily and species varied by trap type. SLAM traps should be considered as a strong tool to describe cerambycid communities when used in conjunction with pheromones and host volatiles.

Arboreal insects associated with herbicide-stressed Pinus resinosa and Pinus sylvestris used as Sirex noctilio trap trees in New York.

ABSTRACT In September of 2004, Sirex noctilio F. (Hymenoptera: Siricidae) was detected in New York State and later found to be established over a larger area, including parts of southeastern Canada and the northeastern United States. A key component of S. noctilio detection and management plans in other parts of the world where S. noctilio has become established are chemically girdled trap trees. Trap tree usage in North America is confounded by the presence of diverse communities of organisms that inhabit dead and dying trees. We trapped a portion of the arboreal insect community arriving at Pinus resinosa Ait. and Pinus sylvestris L., trap trees girdled 3 mo before (April), one month before (June), and at S. noctilio flight (July) in central New York. Multiple-funnel traps attached to trap trees captured 30,031 individuals from 109 species of Scolytinae, Cerambycidae, and Siricidae. Ipspini (Say) and Ips grandicollis (Eichhoff) accounted for almost 50% of the scolytines captured at trap trees and were present on all girdling dates. Significantly more scolytines and cerambycids were captured on P. sylvestris compared with P. resinosa, but species richness of captured insects did not differ between the two trees. More total and conifer-inhabiting scolytines and cerambycids were captured in traps on trees girdled in April and June and higher observed species richness was found on trees girdled in April and controls. Results from this study suggest a large community of arboreal insects and associated organisms are attracted to chemically girdled trap trees and likely interact with S. noctilio.

Do Native Insects and Associated Fungi Limit Non-Native Woodwasp, Sirex noctilio, Survival in a Newly Invaded Environment?

Sirex noctilio F. (Hymenoptera: Siricidae) is an introduced pest of pines (Pinus spp.) in several countries in the Southern Hemisphere. Although S. noctilio is established in North America (first discovered in 2004), it has not been a destructive pest there so far, where forest communities more closely resemble those in its native Eurasian range—where it is not a pest. To investigate the influence of the existing community of associated insects (competitors + natural enemies) and fungi (vectored by insects) on S. noctilio survival in North America, we examined stage-specific mortality factors and their relative importance, generating life tables drawn from experimentally-manipulated and natural cohorts of Sirex spp. (mostly S. noctilio, but some native S. nigricornis F.). For both natural and experimentally-manipulated cohorts, factors which acted during the earliest Sirex life stages, most likely tree resistance and/or competition among fungal associates, were paramount in dictating woodwasp survival. Experimentally-manipulated life tables revealed that protection from the community of associates resulted in a significantly, and substantially larger (>15x) S. noctilio F1 generation than exposure to it. Seventy percent of generation mortality in the exposed cohort was due to tree resistance or unknown causes early in larval development, which could have included competition among other bark- or wood-inhabiting insects and/or their fungal associates. Only 46% of generation mortality in the protected cohort was due to tree resistance and/or unknown causes. Parasitoids, particularly endoparasitoids (Ibalia spp.), showed limited ability to control S. noctilio, and reduced the experimentally-established cohort by only 11%, and natural cohorts an average of 3.4%. The relative importance of tree resistance vs. competition with bark- and wood-borers in reducing S. noctilio survival remains unclear. Tree resistance and/or competition likely contribute more than natural enemies in maintaining the S. noctilio population in North America below damaging levels.