National Trade can Drive Range Expansion of Bark- and Wood-Boring Beetles

Mortality of Bark- and Wood-boring Beetles (Coleoptera: Buprestidae, Cerambycidae, and Curculionidae) in Naturally Infested Heat-treated Ash, Birch, Oak, and Pine Bolts

Firewood and wood packaging material (WPM) are major pathways for moving bark- and wood-infesting insects (borers). Heat treatment regulations for interstate firewood movement vary among U.S. states: from 56°C for 30 min to 71.1°C for 75 min. Current WPM international standards (ISPM 15) require heating to a minimum of 56°C for 30 min throughout the profile of the wood. Using bolts from infested ash (Fraxinus), birch (Betula), oak (Quercus), and pine (Pinus) trees in Michigan, we assessed borer mortality at core temperatures of 50, 53, 56, and 60°C maintained for 30 min in chambers set to 60, 65, 70, or 75°C. After treatment, bolts were monitored for adult emergence and later dissected to determine borer mortality rates. Mortality was high to complete for all heat treatments and increased with both increasing core and chamber temperatures. For the Agrilus (Buprestidae) species tested, there was complete mortality of Agrilus anxius on birch and Agrilus planipennis on ash when core temperatures of 56°C or higher were targeted regardless of chamber temperature. However, on oak, a few Agrilus bilineatus and Agrilus sulcicollis survived in bolts heated to 56°C in chambers at 60 and 65°C, and some A. sulcicollis survived in chambers set at 70 and 75°C. Similarly, a few pine-infesting borers survived heating to 56°C at all chamber temperatures. However, there was complete mortality in all hosts when bolts were heated to 60°C for 30 min, regardless of chamber temperature. Results are discussed in terms of current treatment regulations for firewood and WPM.

Geographical Distribution of Three Forest Invasive Beetle Species in Romania

Ips duplicatus (Sahlberg, 1836), Xylosandrus germanus (Blandford, 1894) and Neoclytus acuminatus (Fabricius, 1775) are invasive species reported in Romania, but their current distribution is poorly known. The research aim was to provide new information on this issue. A survey was conducted over the period 2015–2017 in 82 locations, using flight-interception traps and bottle traps, baited with different attractants. Data obtained in our other unpublished studies were also taken into account. A total of 35,136 I. duplicatus beetles were collected in 30 survey locations. The highest captures were in the log yards of some factories processing logs of Norway spruce (Picea abies (L.) H. Karst.). Considering all known records so far, most of these are in the eastern part of Romania, where an outbreak took place during the years 2005–2014, mainly in spruce stands growing outside their natural range. During the survey, 4259 specimens of X. germanus were collected in 35 locations, but in our other studies the species was found in 13 additional places. It was collected at altitudes of 18–1200 m, and the largest catches were from beech stands, growing at 450–950 m. N. acuminatus was found in only six locations, in the western and southern parts of the country, at low altitudes, in tree stands composed of Fraxinus excelsior L., Quercus spp. and other broadleaf species, as well as in broadleaf log yards. The results suggest that I. duplicatus is established in most parts of the Norway spruce’s range, X. germanus is still spreading in the country, with some areas having quite high populations, while N. acuminatus is present only in the warmest regions of the country.

The Effect of Trap Color on Catches of Monochamus galloprovincialis and Three Most Numerous Non-Target Insect Species

Simple Summary

The pine sawyer, Monochamus galloprovincialis, is a longhorned beetle widespread in Europe. It develops in severely weakened, dying, or recently dead pine trees. The importance of M. galloprovincialis has increased since it was shown to be a vector of the alien and invasive pine wood nematode, Bursaphelenchus xylophilus, which can kill pines within a year. Pheromone traps are the most useful tools for monitoring M. galloprovincialis. While black traps are most commonly used, the objective of our studies was to test the attractiveness of different colors to immature and mature M. galloprovincialis and three non-target species. The results could be useful in selecting an optimal color that is attractive to M. galloprovincialis, but minimizes bycatch of non-target insects. A total of twenty colors were tested, including nine colors tested in the field, using cross-vane traps. The unpainted white traps were found to be most attractive to M. galloprovincialis and can be used to increase catches of this insect. However, the predatory beetles Thanasimus spp. responded to the trap color in the same way as M. galloprovincialis; therefore, either trap design or lure composition should be modified to reduce the impact on these beneficial insects.

Abstract

Black pheromone-baited traps are commonly used for monitoring Monochamus galloprovincialis, a vector of Bursaphelenchus xylophilus, although few studies have been conducted on its response to color (black, white, and clear). The objective of our studies was to evaluate the attractiveness of different colors to M. galloprovincialis and non-target species: Spondylis buprestoides and predatory Thanasimus formicarius and T. femoralis. Laboratory tests of fifteen colors against immature and mature M. galloprovincialis revealed some differences in their color preference. In two field tests, eight colors of coroplast vanes in cross-vane traps were compared with unpainted white (a reference (RF)). The first test confirmed the laboratory results, i.e., RF was slightly more attractive to M. galloprovincialis than pastel yellow, reseda green, and cyan blue, but trap color had no significant effect on any of the insect species studied. In the second test, the attractiveness of RF was highest and significantly different from pure white (for all four species), light blue, and pine green (except S. buprestoides). Overall, the unpainted white traps appeared to be most effective in catching M. galloprovincialis. Thanasimus spp. responded to the colors similarly to M. galloprovincialis; therefore, either trap design or lure composition should be modified to reduce their catches.

Maximizing Bark and Ambrosia Beetle (Coleoptera: Curculionidae) Catches in Trapping Surveys for Longhorn and Jewel Beetles

Bark and ambrosia beetles are commonly moved among continents within timber and fresh wood-packaging materials. Routine visual inspections of imported commodities are often complemented with baited traps set up in natural areas surrounding entry points. Given that these activities can be expensive, trapping protocols that attract multiple species simultaneously are needed. Here we investigated whether trapping protocols commonly used to detect longhorn beetles (Coleoptera: Cerambycidae) and jewel beetles (Coleoptera: Buprestidae) can be exploited also for detecting bark and ambrosia beetles. In factorial experiments conducted in 2016 both in Italy (seminatural and reforested forests) and Canada (mixed forest) we tested the effect of trap color (green vs purple), trap height (understory vs canopy), and attractive blend (hardwood-blend developed for broadleaf-associated wood-boring beetles vs ethanol in Italy; hardwood-blend vs softwood-blend developed for conifer-associated wood-boring beetles, in Canada) separately on bark beetles and ambrosia beetles, as well as on individual bark and ambrosia beetle species. Trap color affected catch of ambrosia beetles more so than bark beetles, with purple traps generally more attractive than green traps. Trap height affected both beetle groups, with understory traps generally performing better than canopy traps. Hardwood-blend and ethanol performed almost equally in attracting ambrosia beetles in Italy, whereas hardwood-blend and softwood-blend were more attractive to broadleaf-associated species and conifer-associated species, respectively, in Canada. In general, we showed that trapping variables suitable for generic surveillance of longhorn and jewel beetles may also be exploited for survey of bark and ambrosia beetles, but trapping protocols must be adjusted depending on the forest type.

Effect of Trap Color on Captures of Bark-and Wood-Boring Beetles (Coleoptera; Buprestidae and Scolytinae) and Associated Predators

Simple Summary

Several wood-associated insects are inadvertently introduced every year within wood-packaging materials used in international trade. These insects can cause impressive economic and ecological damage in the invaded environment. Thus, several countries use traps baited with pheromones and plant volatiles at ports of entry and surrounding natural areas to intercept incoming exotic species soon after their arrival and thereby reduce the likelihood of their establishment. In this study, we investigated the performance of eight trap colors in attracting jewel beetles and bark and ambrosia beetles to test if the trap colors currently used in survey programs worldwide are the most efficient for trapping these potential forest pests. In addition, we tested whether trap colors can be exploited to minimize inadvertent removal of their natural enemies. Our results confirmed that trap color strongly affects trapping performance. Overall, the trap colors currently adopted in most survey programs (i.e., green and black) are efficient only for certain beetle species, therefore there is a clear need to use additional trap colors to increase the range of species that can be effectively attracted. Moreover, we confirmed that many predators exploit the same visual cues as their preys, and thus trap color cannot be used as a variable to minimize bycatch.

Abstract

Traps baited with attractive lures are increasingly used at entry-points and surrounding natural areas to intercept exotic wood-boring beetles accidentally introduced via international trade. Several trapping variables can affect the efficacy of this activity, including trap color. In this study, we tested whether species richness and abundance of jewel beetles (Buprestidae), bark and ambrosia beetles (Scolytinae), and their common predators (i.e., checkered beetles, Cleridae) can be modified using trap colors different to those currently used for surveillance of jewel beetles and bark and ambrosia beetles (i.e., green or black). We show that green and black traps are generally efficient, but also that many flower-visiting or dark-metallic colored jewel beetles and certain bark beetles are more attracted by other colors. In addition, we show that checkered beetles have color preferences similar to those of their Scolytinae preys, which limits using trap color to minimize their inadvertent removal. Overall, this study confirmed that understanding the color perception mechanisms in wood-boring beetles can lead to important improvements in trapping techniques and thereby increase the efficacy of surveillance programs.

Sulcatol: Enantiospecific Attractant for Monarthrum mali (Coleoptera: Curculionidae: Scolytinae), Leptostylus asperatus (Coleoptera: Cerambycidae) and Associated Predators

In 2014-2019, we conducted six experiments in north-central Georgia in an attempt to verify the aggregation pheromone response of the ambrosia beetle Gnathotrichus materiarius (Fitch) (Coleoptera: Curculionidae: Scolytinae: Scolytini: Corthylina) to sulcatol known to be produced by male G. materiarius; we failed to catch any G. materiarius. However, we did find that another corthyline ambrosia beetle species Monarthrum mali (Fitch) was attracted to (R)-(-)-sulcatol, whereas the longhorn beetle Leptostylus asperatus (Haldeman) (Coleoptera: Cerambycidae: Lamiinae) was attracted to (S)-(+)-sulcatol. Attraction of both species was unaffected by the respective antipodes. Ethanol enhanced attraction of both species to traps baited with sulcatol. In at least one experiment, attraction to ethanol-baited traps was enhanced by sulcatol for Xylosandrus crassiusculus (Motschulsky), Xyleborus spp., and Hypothenemus spp. but reduced for Cnestus mutilatus (Blandford) (Coleoptera: Curculionidae: Scolytinae). Additionally, traps baited with ethanol and racemic sulcatol [50% (S)-(+): 50% (R)-(-)] caught the greatest numbers of four species of beetle predators: Coptodera aerata Dejean (Coleoptera: Carabidae), Colydium lineola Say (Coleoptera: Zopheridae), Madoniella dislocata (Say), and Pyticeroides laticornis (Say) (Coleoptera: Cleridae). Ethanol but not sulcatol attracted Temnoscheila virescens (F.) (Coleoptera: Trogossitidae). Information on interspecific relationships within forested communities may help us to better determine the roles of these species in maintaining stable and resilient forested ecosystems.

Variable Responses to Novel Hosts by Populations of the Seed Beetle Callosobruchus maculatus (Coleoptera: Chrysomelidae: Bruchinae)

Cosmopolitan pests can consist of geographic populations that differ in their current host ranges or in their ability to colonize a novel host. We compared the responses of cowpea-adapted, seed-beetle populations (Callosobruchus maculatus [F.] (Coleoptera: Chrysomelidae: Bruchinae)) from Africa, North America, and South America to four novel legumes: chickpea, lentil, mung bean, and pea. We also qualitatively compared these results to those obtained earlier for an Asian population. For each host, we measured larval survival to adult emergence and used both no-choice and choice tests to estimate host acceptance. The pattern of larval survival was similar among populations: high or moderately high survival on cowpea, mung bean, and chickpea, intermediate survival on pea, and very low survival on lentil. One exception was unusually high survival of African larvae on pea, and there was modest variation among populations for survival on lentil. The African population was also an outlier with respect to host acceptance; under no-choice conditions, African females showed a much greater propensity to accept the two least preferred hosts, chickpea and lentil. However, greater acceptance of these hosts by African females was not evident in choice tests. Inferences about population differences in host acceptance can thus strongly depend on experimental protocol. Future selection experiments can be used to determine whether the observed population differences in initial performance will affect the probability of producing self-sustaining populations on a marginal crop host.