Catching Ips duplicatus (Sahlberg) (Coleoptera: Scolytidae) with pheromone-baited traps: optimal trap type, colour, height and distance to infestation

Increased capture efficiency of Scolytinae with modified semi-funnel trap model

Abstract Scolytinae species that, in high populations, can damage reducing wood production in forest crops. These beetles are monitored with traps baited with ethanol and increasing their efficiency can improve the integrated management of these insects. The objective was to evaluate the increase in the capture efficiency of Scolytinae with a semi-funnel trap model, in two experiments, one including wooden elements and other increasing the flight interception area and to correlate the numbers of these beetles collected with climatic factors. In the experiment 1, Eucalyptus urophylla S. T. Blake slats were directly attached to the collector flask and in another treatment, in addition to these slats, Cedrela sp. strips were inserted inside the bait holding hose. In the experiment 2, the insect interception area in the trap, originally 480 cm2, was expanded to 1,200 cm2 and compared with the model Pet–Santa Maria trap with an interception area of 550 cm2. Weekly collections were carried out between May 2018 and June 2019. The beetles collected were taken to the Wood Biodeterioration Laboratory of the Federal Rural University of Rio de Janeiro (UFRRJ) where they were sorted, identified at family level, counted and their number correlated with climatic factors. Statistical analyzes of the collected data were processed by the BioStat® 5.3 program. In the experiment 1 were collected 869 Scolytinae. The numbers of beetles collected per trap without modification, with E. urophylla slats and E. urophylla slats + Cedrela sp. strips were similar, 7.3 ± 3.8, 7.8 ± 6.2 and 7.7 ± 5.0 respectively. In the experiment 2 were collected 4,398 Scolytinae. Increasing the interception area of the beetles increased the efficiency of the semi-funnel trap, with 42.7 ± 20.5 Scolytinae collected compared to the original semi-funnel trap, 28.6 ± 12.6 and the Pet–Santa Maria, 20.4 ± 10.4, per trap. The number of Scolytinae did not correlate with climatic factors in the experiment 1 and it was correlated with temperature, relative humidity and wind speed, but not with precipitation, in the 2. The incorporation of E. urophylla slats or Cedrela sp. strips in the semi-funnel trap did not increase the number of beetles collected, but, the increase in the flight interception area and the temperature, relative humidity and wind speed were correlated with the number of beetles collected.

Photosensitivity of Dispersing Cryptic Date Stone Beetles Coccotrypes dactyliperda (Coleoptera, Curculionidae, Scolytinae)-A Pilot Study

The date stone beetle, Coccotrypes dactyliperda, is a cryptic spermatophagus species that spends almost its entire life cycle inside the seeds of palms, esp. Phoenix sp. Only during dispersal, when the host seed has been largely eaten out, do females emerge for a short period of time in search of a fresh seed in which to establish new brood galleries. Previous work indicated that C. dactyliperda might be photophobic, preferring to emerge from seeds during night hours, whereas anecdotal evidence suggested that the beetles might be photophilic in terms of their movements post emergence. This paper examines the photosensitivity of the species under controlled laboratory conditions. The results show that C. dactyliperda, once removed from the brood chamber, is attracted by and moves faster to a light source, but that the color of the lit surface (red, blue, green, black) has no influence on either direction or crawl speed.

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.

Efficiency and Sustainability of Ips duplicatus (Coleoptera: Curculionidae) Pheromone Dispensers with Different Designs

Ips duplicatus (Coleoptera: Curculionidae) is a bark beetle that recently invaded southern Europe. It produces intense outbreaks in the spruce stands installed outside their natural area. Pheromone dispensers with different designs are used for monitoring this species. Compounds are released either by wick (ID Ecolure) or polyethene foil (ID RO and Pheagr IDU). We performed a series of laboratory and field experiments to compare the efficiency and sustainability of these dispensers in terms of pheromone release. The first experiment compared the Ips duplicatus capture dynamics between the ID Ecolure and ID RO in pheromones traps in three localities for 60 days. Release rates of used dispensers were evaluated in the same period. The second experiment analyzed headspace chemical composition in three dispensers (ID Ecolure, ID RO, Pheagr IDU) and tested their activity in pheromone traps. Active compounds content released by tested dispensers varied. The wick dispensers’ release rates (ID Ecolure) were strongly reduced from 365 to 50 mg/day within two weeks and then steadily to 16 mg/day after 60 days. Release rates of the polyethene dispensers (ID RO) remained constant over 60 days (20–24 mg/day). The highest initial emission was in the ID Ecolure. The ratio of pheromone components (ipsdienol/E-myrcenol) was lower for ID Ecolure (5) and ID RO (10) and higher for Pheagr IDU (565). In the field experiments, significantly more Ips duplicatus were caught with ID Ecolure than ID RO and Pheagr IDU in the first two weeks. Later, the attractivity of ID RO remained high, but captures by ID Ecolure were significantly reduced. The captures of Ips typograhus were also considered. We propose that the wick-type dispensers are a promising tool for controlling the hibernating beetle generation. The foil release dispensers can be used to monitor Ips duplicatus flight activity.

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.

Optimising Vine Weevil, Otiorhynchus sulcatus F. (Coleoptera: Curculionidae), Monitoring Tool Design

Simple Summary

Vine weevil remains one of the most economically important insect pests of soft-fruit and ornamental crops globally. Growers currently lack effective monitoring systems to determine presence of vine weevil within crops, meaning that controls are often applied too late to prevent economic losses. Development of improved monitoring systems is currently hindered by a lack of knowledge of whether vine weevil adults select a monitoring tool based on its visual appearance. This study used paper cups as refuges to investigate the importance of colour, shape and position of entrances on monitoring tool efficacy. Results indicate that dark, tall refuges with entrances around their base were preferentially entered by adult vine weevil. This information provides the first steps towards developing improved designs for vine weevil monitoring tools.

Abstract

Vine weevil, Otiorhynchus sulcatus F. (Coleoptera: Curculionidae), is an economically important insect pest of horticultural crops. To identify an effective and reliable monitoring system for adult vine weevil, this study investigated the influence of colour, height and entrance position on the efficacy of a model monitoring tool using modified paper cups as refuges. Vine weevil preferences were determined by the number of individuals recorded within a refuge. When provided with a binary choice between black or white refuges, vine weevil adults showed a preference for black refuges. Vine weevils provided with a range of coloured refuges (blue, green, red and yellow) in addition to black and white refuges showed a preference for black and blue over the other colours and white refuges in group choice experiments. Refuge height and entrance position also influenced vine weevil behaviour with individuals exhibiting a preference for taller refuges and those with entrance openings around the refuge base. These results provide insights into refuge selection by adult vine weevils, which can be exploited to improve monitoring tool design. The importance of developing an effective monitoring tool for vine weevil adults as part of an integrated pest management programme is discussed.

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.

Estimating Flight Distance of Platypus koryoensis (Coleoptera: Curculionidae) by Mark-Release-Recapture and Its Validation by Field Observation

Korean oak wilt (KOW) is vectored by the beetle Platypus koryoensis (Murayama) (Coleoptera: Curculionidae), a native species of Korea, whose dispersal distance is a key factor determining the spread of damage by KOW. To estimate dispersal distance at stand level, we conducted a mark-release-recapture (MRR) experiment and validated its results using an independent data. Sticky traps were attached to the trunks of oak trees up to 48.8 m from the release point. Beetles were marked with different three fluorescent powders by date and released, and the number of recaptured beetles was counted 90 min after release. To validate the flight distance, annual mean dispersal distance of P. koryoensis population was analyzed using GPS coordinates of oak trees with the symptom of KOW recorded in the field from 2012 to 2014 in independent oak stands that have been damaged by KOW since 2012. The beetles were recaptured only on the day they were released, suggesting that the beetles only make one flight. The percentage of recaptured beetles was 6.0 ± 1.6%. The mean dispersal distance was 18.0 ± 1.3 m, and more than 85% of recaptured beetles were caught within 25 m. Annual movement distances in infested stands were 24.1 and 19.9 m from 2012 to 2013 and 2013 to 2014, respectively, similar to the dispersal distance obtained from our MRR experiment. Our results showed that the dispersal distance of P. koryoensis estimated by MRR is a useful process for predicting the spread of areas damaged by KOW.

Pest categorisation of Ips duplicatus

The Panel on Plant Health performed a pest categorisation of the double-spined bark beetle, Ips duplicatus (Sahlberg, 1836) (Coleoptera: Curculionidae, Scolytinae), for the EU. I. duplicatus is a well-defined and distinguishable species, native to Europe and attacking mainly spruce (Picea spp.) but also observed on pine (Pinus spp.) and larch (Larix spp.). It is distributed in 15 EU Member States and is locally spreading in some of them. I. duplicatus is listed in Annex IIB of Council Directive 2000/29/EC. Protected zones are in place in Ireland, Greece and the United Kingdom. Wood, wood products, bark, and wood packaging material are considered as pathways for this pest, which is also able to disperse by flight. The insects mostly attacks scattered individual standing trees in the stands, often when the trees are weakened by dry conditions or by pathogens, and they very rarely infest fallen or cut logs. The males produce pheromones that attract conspecifics of both sexes. Each male attracts 1-5 females and they establish a brood system; each female produces 1-60 offspring. The insects also inoculate their hosts with pathogenic fungi. There are one to three generations per year. The current geographic range of I. duplicatus suggests that it is able to establish in most of the EU, including the protected zones, where its hosts are present. Sanitary thinning or clear-felling and pheromone trapping are the usual control methods. All criteria for consideration as potential protected zone quarantine pest are met. The criteria for considering I. duplicatus as a potential regulated non-quarantine pest are not met since plants for planting are not viewed as a pathway.

The Impact of Trap Type and Design Features on Survey and Detection of Bark and Woodboring Beetles and Their Associates: A Review and Meta-Analysis

A large literature on the survey and detection of forest Coleoptera and their associates exists. Identification of patterns in the effect of trap types and design features among guilds and families of forest insects would facilitate the optimization and development of intercept traps for use in management programs. We reviewed the literature on trapping bark and woodboring beetles and their associates and conducted meta-analyses to examine patterns in effects across guilds and families; we observed the following general patterns: (a) Panel traps were superior to multiple-funnel traps, (b) bark beetles and woodborers were captured in higher numbers in traps treated with a surface treatment to make them slippery than untreated traps,

Novel Chemo-Attractants for Trapping Tomato Leafminer Moth (Lepidoptera: Gelechiidae)

The tomato leafminer moth, Tuta absoluta (Meyrick), is a devastating pest for tomatoes in Iran and throughout the world. This pest reduces tomato yields in farms and greenhouses. It appears some floral odors are significant attractants for tomato leafminer moth. In this study, the effects of three floral compounds, phenylacetaldehyde (PAA), acetic acid (AA), and 3-methyl-1-butanol (MB), were evaluated as trap attractants for tomato leafminer moth. The attractants were tested separately, combined, and blended in binary and tertiary. Lures were tested in delta and water pan traps under field conditions and compared with unbaited traps as controls. Results indicated that water pan traps caught more moths than delta traps. Also treatments with PAA + AA combined and the AA + MB blend were strongly attractive to tomato leafminer moth males compared with other treatments in this study.

Crepuscular flight activity of an invasive insect governed by interacting abiotic factors

Seasonal and diurnal flight patterns of the invasive walnut twig beetle, Pityophthorus juglandis, were assessed between 2011 and 2014 in northern California, USA in the context of the effects of ambient temperature, light intensity, wind speed, and barometric pressure. Pityophthorus juglandis generally initiated flight in late January and continued until late November. This seasonal flight could be divided approximately into three phases (emergence: January-March; primary flight: May-July; and secondary flight: September-October). The seasonal flight response to the male-produced aggregation pheromone was consistently female-biased (mean of 58.9% females). Diurnal flight followed a bimodal pattern with a minor peak in mid-morning and a major peak at dusk (76.4% caught between 1800 and 2200 h). The primarily crepuscular flight activity had a Gaussian relationship with ambient temperature and barometric pressure but a negative exponential relationship with increasing light intensity and wind speed. A model selection procedure indicated that the four abiotic factors collectively and interactively governed P. juglandis diurnal flight. For both sexes, flight peaked under the following second-order interactions among the factors when: 1) temperature between was 25 and 30 °C and light intensity was less than 2000 lux; 2) temperature was between 25 and 35 °C and barometric pressure was between 752 and 762 mba (and declined otherwise); 3) barometric pressure was between 755 and 761 mba and light intensity was less than 2000 lux (and declined otherwise); and 4) temperature was ca. 30 °C and wind speed was ca. 2 km/h. Thus, crepuscular flight activity of this insect can be best explained by the coincidence of moderately high temperature, low light intensity, moderate wind speed, and low to moderate barometric pressure. The new knowledge provides physical and temporal guidelines for the application of semiochemical-based control techniques as part of an IPM program for this invasive pest.

Field evaluation of synthetic sex pheromone traps for the cocoa mirid Sahlbergella singularis (Hemiptera: Miridae)

BACKGROUND

Field trapping experiments were conducted to evaluate the attractiveness of five different pheromone blends as well as the impact of trap design on attractiveness towards cocoa mirids, Sahlbergella singularis Hagl. and Distantiella theobroma (Dist.), in Cameroon.

RESULTS

A total of 361 adults of S. singularis (359 males and two females) were caught. The highest numbers of mirids were found in traps with pheromone blends that combined a monoester and a diester, compared with traps with the diester or the monoester individually and control traps with no pheromone. Rectangular traps caught significantly more mirids compared with delta traps. The mean number of 5.1 mirids trap⁻¹ year⁻¹ caught in rectangular traps was significantly higher compared with the 1.8 mirids trap⁻¹ year⁻¹ for the delta traps.

CONCLUSION

The data revealed that rectangular traps containing pheromone blends combining both the monoester and the diester have a good potential to lure and trap adult males of S. singularis on cocoa farms. The pheromone blends used were specific for S. singularis, and the use of pheromone traps appears to be a promising strategy for incorporation into integrated pest management strategies for the monitoring or even the control of S. singularis in cocoa plantations.

Olfactory and visual responses of the longlegged chafer Hoplia spectabilis Medvedev (Coleoptera: Scarabaeidae) in Qinghai Province, China

BACKGROUND

Monitoring traps and control methods are needed for the long-legged chafer, Hoplia spectabilis Medvedev, which has recently reached outbreak numbers in pastureland of Qinghai Province, China.

RESULTS

Field trapping experiments, using cross-pane funnel (barrier) traps, showed that H. spectabilis adults were not significantly attracted to branches of the host plant Dasiphora fructicosa (L.) Rydb. However, beetles were slightly attracted to similar host plant branches infested by conspecific beetles, possibly owing to weakly attractive volatiles, primarily (Z)-3-hexenyl acetate, released from beetle-damaged host leaves. This compound was weakly attractive when released from traps. However, H. spectabilis beetles showed strong visual responses to yellow- or white-painted trap panes, with weaker responses to blue, red or green panes, and least response to black panes. Black traps at 0.2-1.5 m above ground intercepted significantly more beetles than traps at 2.5 m. The mean flight height based on trap catches was 0.88 m (SD = 0.76), yielding an effective flight layer of 1.9 m. Flight response of beetles to colored barrier traps occurred between 10:00 and 18:00, and peaked between 12:00-14:00, when daily temperatures reached their maximum.

CONCLUSION

Unbaited yellow or white cross-pane funnel traps are recommended for both monitoring and mass-trapping programs against this economically and ecologically important scarab beetle.