Hole density and capture of stored-product insect pests in grain probe traps

The relationship between number of holes in a grain probe trap body and capture of stored-grain pests was determined in laboratory tests using adults of the rice weevil, Sitophilus oryzae (L.), the sawtoothed grain beetle, Oryzaephilus surinamensis (L.), and the red flour beetle, Tribolium castaneum (Herbst). Polyvinylchloride (PVC) probe bodies were attached to electronic sensor heads, and insect captures were recorded electronically using an Electronic Grain Probe Insect Counter (EGPIC) system. In comparisons among PVC probe trap bodies with 60-492 holes, tested at 71 insects per kg in 2.8 kg of soft wheat in cylindrical mini-silos, sawtoothed grain beetle and rice weevil captures were directly related to number of holes in the probe trap body, but there was no relationship for red flour beetle capture. Subsequent tests were conducted comparing sawtoothed grain beetle and rice weevil captures in a PVC probe body with 210 holes over a 40-cm long trapping surface with two commercially available probe traps, a polycarbonate (Lexan) probe trap with 180 holes over a 14-cm long trapping surface and a polyethylene (WBII) probe trap with 750 holes over a 34-cm long trapping surface. The highest percentage capture of both species was in the WBII probe trap, but the 210-hole PVC probe body was as effective as the Lexan probe body for rice weevils and sawtoothed grain beetles at 71 and 17 insects per kg of wheat, respectively.     

Evaluating light attraction to increase trap efficiency for Tribolium castaneum (Coleoptera: Tenebrionidae)

The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), is a major coleopteran pest in flour mills and storage facilities. An aggregation pheromone has been identified for this pest; however, the pheromone is of limited value for population monitoring. To develop more efficient methods to monitor this pest, experiments were conducted to determine whether light functioned as an attractant for the red flour beetle. Light-emitting diodes (LEDs) of various wavelengths were examined as light sources because they produce bright, narrow light spectra. A comparison of responses to light spectra across the visible and UV regions of the electromagnetic spectrum indicated that the beetle was most attracted to near UV LED at a 390 nm dominant wavelength. The use of LEDs in competitive laboratory experiments resulted in a 20% capture of released beetles, compared with a 1% capture with the aggregation pheromone alone. Even more beetles were captured with a combination of LEDs and commercially available chemical lures in traps. LEDs can easily be added onto existing trap designs or new traps can be designed to take full advantage of positive phototaxis.     

Influence of environmental and physical factors on capture of Tribolium castaneum (Coleoptera: Tenebrionidae) in a flour mill

Variation in environmental and physical factors within food processing facilities can influence both the distribution of stored-product pests and trapping efficiency. Data from a long-term Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) monitoring program was used to evaluate spatial variation in captures among trap locations and to determine relationships with environmental and physical variables. From the complete monitoring data set, different subsets were created for the cool and warm seasons, and period of time when environmental and physical factors were measured (2009-2010), with all data sets showing significant differences among trap locations in terms of beetle captures and proportion of time that traps exceeded 2.5 beetles per trap per monitoring period. There was also considerable temporal variation in distribution among the different levels of the mill. Among the environmental and physical variables measured, mean temperature and flour dust accumulation showed the most significant positive relationships with variation of beetle captures at trap locations. More beetles were captured in traps located in close proximity to milling equipment. Presence of equipment near traps was also associated with an increase in flour dust accumulation and temperature. Overall the environmental and physical factors seemed to have a limited influence on variation in captures among trap locations, with temporal variation in distribution perhaps overwhelming potential influences of local trap conditions.     

Optimization of a valine:isoleucine methyl ester pheromone blend and comparison of Robbins and Trécé traps for capture of Phyllophaga anxia (Coleoptera: Scarabaeidae) in Rhode Island

Eight ratios of L-valine:L-isoleucine methyl esters were tested in Robbins traps for capture of Phyllophaga anxia (LeConte) adult males. The 90:10, 80:20, and 60:40 ratios of valine:isoleucine were the most effective blends for capture of beetles in Rhode Island. Females were captured in small numbers in some traps but not consistently to any particular blend. Other male Phyllophaga species captured included Phyllophaga fusca (Fr?lich), Phyllophaga forsteri (Burmeister), P. hirsuta (Knoch), and P. marginalis (LeConte). The number of these species collected was low, and it was not possible to determine whether they were attracted to any particular pheromone blend. Peak captures of P. anxia males occurred 31 May in 1999 and 2002 in Kingston, RI. The standard Japanese beetle trap manufactured by Trécé (Adair, OK) captured significantly more beetles than the Robbins trap. Because the Trécé trap is already marketed for Japanese beetles, a lure and trapping system can be adopted for P. anxia.     

Dynamics of abundance of ground beetles (Coleoptera,Carabidae) in fenced areas in the Cis-Altai plain (Western Siberia)

The density of ground beetle populations was estimated by means of fenced pitfall traps in 2004–2008, in the environs of Biisk (Altai Territory) and Karasuk (Novosibirsk Province). In all, 64 species of ground beetles were revealed. The capture rates were usually higher in open than in fenced plots. No correlation was observed between the time of trap exposure and the captures. By the end of the 3rd–6th week of exposure, the fraction of juvenile and immature adults increased. The beetles captured within a fenced area 1 m² usually fell into the traps in 2–3 days. The maximal density of carabids in the fenced areas was estimated at 55–60 ind./m².     

Influence of visual and olfactory cues on field trapping of the pollen beetle, Astylus atromaculatus (Col.: Melyridae)

Field trapping experiments investigated the response of the pollen beetle Astylus atromaculatus to visual and olfactory cues during a 3-year period, 1999–2001. The visual preference of the pollen beetle was determined using yellow, white, blue, green and red water traps. The yellow trap was most attractive, capturing 56% of the total beetles trapped, with 30% caught by the blue and white traps, while 14% was caught by the red and green traps. The response of the beetle to olfactory cues was then evaluated by using the yellow water trap with three antennally active components identified in the volatiles of sorghum panicles by coupled gas chromatography (GC)–electroantennographic detection and GC–mass spectrometry. These components were 2-phenylethanol, benzyl alcohol and linalool. There were no significant colour × chemical compound interactions and traps baited with 2-phenylethanol captured significantly more beetles than unbaited traps, irrespective of trap colour, demonstrating the effectiveness of olfactory cues in trapping the pollen beetle. Traps baited with 2-phenylethanol were more attractive than and caught more beetles than traps baited with linalool. 2-Phenylethanol had the greatest effect on the relatively unattractive blue trap, confirming the importance of olfactory cues mediating A. atromaculatus attraction .     

Influence of trap type, trap colour, and trapping location on the capture of the pine moth, Thaumetopoea pityocampa

Studies were conducted to evaluate the effect of type, location, and colour of traps baited with 1 mg of the sex pheromone (Z)‐13‐hexadecen‐11‐ynyl acetate in polyethylene vials on the capture of the pine processionary moth, Thaumetopoea pityocampa (Denis & Schiffermüller) (Lepidoptera: Thaumetopoeidae), males. The experiments were carried out during two flight seasons in 2002 and 2003 at a low elevation Mediterranean pine forest on the hill of Goritsa (Magnesia, Thessaly, Central Greece). The hill is covered by approximately 120 ha of pines, among which Pinus brutia Ten. (Pinaceae) is predominant with Pinus halepensis Mill. (Pinaceae) as second most common species. Among the commercially available trap types used, the Delta and Pherocon II captured significantly more males than the Funnel trap. Furthermore, pine density had a significant effect on trap type and trap colour catches. Delta traps caught significantly more adults than the other two trap types in the low density pine stand, while in the medium and high‐density pine stands no significant differences were noted between Delta and Pherocon II traps. In addition, trap colour performance varied according to pine density; white‐ and yellow‐coloured traps caught significantly more males than the other two trap colours in the high‐density stand. The first adults were captured in traps during May, and traps continued to capture adults in low numbers (< two individuals per trap) until mid‐June. A period of 3–4 weeks of no trap captures followed until mid‐July, when captures restarted, at low numbers. The peak of T. pityocampa flight was observed during late August–September.     

Monitoring stored-product pests in food processing plants with pheromone trapping,contour mapping,and mark-recapture

Distribution and movement patterns of several species of stored-product pests in a food processing plant were investigated. The objectives of this study were to determine the temporal and spatial variation in abundance of stored-product pests using pheromone traps; assess the effectiveness of trap type, location, and number on monitoring insect populations; and to evaluate the nature of pheromone trap capture hot spots by measuring patterns of insect movement. We determined that the distributions of Trogoderma variabile Ballion, Lasioderina serricorne (F.), Tribolium castaneum (Herbst), and Plodia interpunctella (Hübner) within the facility were typically clumped and that foci of high trap captures, based on visual observation of contour maps, varied among species and over time. Trap type and location influenced the number of T. variabile captured: traps on the floor and along walls captured more individuals than hanging traps and traps next to support pillars. T. variabile was the predominant insect pest at this facility and from mark-recapture studies, we found that individual beetles moved across multiple floors in the facility and from 7 to 216 m though the warehouse.     

An ordinal day model of spruce beetle trap capture phenology in northern Colorado

Spruce beetle populations (Dendroctonus rufipennis) (Coleoptera: Scolytinae) in Engelmann spruce (Picea engelmannii) stands were monitored at twelve sites for 6 years in northern Colorado using pheromone‐baited Lindgren funnel traps. During the trapping period, over 30,000 beetles were captured, and beetle abundance data were used to construct empirical models of trap capture phenology based on day of year, accumulation of thermal units and thermal day thresholds, with the goal of informing future regional trapping efforts and producing a simple model for use by forest managers. Ordinal day models outperformed thermal accumulation and thermal threshold models in both predictive power and parsimony. Mean date of earliest capture was Day 153 (June 2) and ranged from Day 126 to Day 161 (May 6–June 10), and mean date of final capture was Day 243 (August 31) and ranged from Day 220 to Day 286 (August 8–October 13). A two‐parameter logistic function was the most parsimonious of several ordinal day models, accounting for 81% of the variance in cumulative trap capture across all sites and dates. The model predicts 50% of trap captures to occur by Day 181 (June 30). This model has application as a decision support tool for forest ecosystem managers concerned with the timing of trap deployment or D. rufipennis mitigation treatments.     

Mass trapping wild Agriotes obscurus and Agriotes lineatus males with pheromone traps in a permanent grassland population reservoir

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Impacts of silvicultural thinning treatments on beetle trap captures and tree attacks during low bark beetle populations in ponderosa pine forests of northern Arizona

Our research used a combination of passive traps, funnel traps with lures, baited trees, and surveys of long-term thinning plots to assess the impacts of different levels of stand basal area (BA) on bark beetle tree attack and on trap captures of Ips spp., Dendroctonus spp., and their predators. The study occurred at two sites in ponderosa pine, Pinus ponderosa Dougl. ex Laws., forests, from 2004 to 2007 during low bark beetle populations. Residual stand BA ranged from 9.0 to 37.0 m2/ha. More predators and bark beetles were collected in passive traps in stands of lower BA than in stands of higher BA; however, significance varied by species and site, and total number of beetles collected was low. Height of the clear panel passive traps affected trap catches for some species at some sites and years. When pheromone lures were used with funnel traps [Ips pini (Say) lure: lanierone, +03/-97 ipsdienol], we found no significant difference in trap catches among basal area treatments for bark beetles and their predators. Similarly, when trees were baited (Dendroctonus brevicomis LeConte lure: myrcene, exo-brevicomin and frontalin), we found no significant difference for days to first bark beetle attack. Surveys of long-term thinning treatments found evidence of bark beetle attacks only in unthinned plots (approximately 37 m2/ha basal area). We discuss our results in terms of management implications for bark beetle trapping and control.     

Comparison of naturally and synthetically baited spruce beetle trapping systems in the central Rocky Mountains

We compared naturally baited trapping systems to synthetically baited funnel traps and fallen trap trees for suppressing preoutbreak spruce beetle, Dendroctonus rufipennis Kirby, populations. Lures for the traps were fresh spruce (Picea spp.) bolts or bark sections, augmented by adding female spruce beetles to create secondary attraction. In 2003, we compared a naturally baited system ("bolt trap") with fallen trap trees and with synthetically baited funnel traps. Trap performance was evaluated by comparing total beetle captures and spillover of attacks into nearby host trees. Overall, the trap systems did not significantly differ in spruce beetle captures, although bolt traps caught 6 to 7 times more beetles than funnel traps during the first 4 wk of testing. Funnel traps with synthetic lures had significantly more spillover than either trap trees or bolt traps. The study was repeated in 2004 with modifications including an enhanced blend synthetic lure. Again, trap captures were generally similar among naturally and synthetically baited traps, but naturally baited traps had significantly less spillover. Although relatively labor-intensive, the bolt trap could be used to suppress preoutbreak beetle populations, especially when spillover is undesirable. Our work provides additional avenues for management of spruce beetles and suggests that currently used synthetic lures can be improved.     

Standardized capture rates of the endangered American burying beetle, Nicrophorus americanus Olivier (Coleoptera: Silphidae) using different trap protocols

The U.S. Fish and Wildlife Service has adopted two different pitfall trap protocols to survey the endangered American burying beetle, Nicrophorus americanus. One protocol uses a transect of eight pitfall traps that prohibit bait contact over the course of three trap nights. The other protocol uses buckets that allow for bait contact over a five night trapping period. A trap night is defined as one trap open for one night, and the transect protocol has historically been calculated as eight trap nights per calendar night while; the bucket protocol has been calculated as one trap night per calendar night. This study examined the effectiveness of each protocol based on the number of beetles (Nicrophorus spp.) captured per trap night (BTN) in field and laboratory trials. When each transect was considered as a single trap instead of eight separate traps, no significant difference in BTN was detected between the protocols in any year. Laboratory trials were conducted using Nicrophorus marginatus to determine differences in capture efficiency based on protocol, time after release, and feeding status. The proportion of beetles captured after 5 days was greater when compared to 3 days for either protocol. Our results indicate that cup transects used to sample the American burying beetle should be considered as a single trap when calculating trap night and that the use of five trap nights rather than three would increase the likelihood of capturing beetles.     

Potential of yellow sticky traps for lady beetle survey in cotton

A 2-yr study was conducted to investigate the potential of using yellow sticky traps to survey lady beetles in cotton and to quantify seasonal activity patterns. The performance of sticky traps was compared with that of a 2-cycle vacuum sampler. The most common lady beetle species captured by sticky traps and vacuum sampler in cotton were Hippodamia convergens Guerin-Meneville and Scymnus loewii Mulsant. Sticky traps captured significantly more of both species of lady beetles, had greater capture efficiency, and more effectively detected lady beetles compared with the vacuum sampler. These data indicate that the sticky trap can be a valuable tool in monitoring lady beetle populations in cotton. In the second part of this study, a year-round survey of lady beetle populations in the periphery of a cotton farm using sticky traps showed that lady beetles remained active throughout the year in the Texas Rolling Plains, but the activity was influenced by winter severity. Over a 2-yr period, H. convergens, S. loewii, Coccinella septempunctata (L.), and Olla v-nigrum (Mulsant) comprised 89.6, 8.2, 1.9, and 0.3% of the specimens, respectively. Sticky trap captures were affected by year, trap height, and cropping season. Traps placed at 0.75 m above ground captured significantly more (80%) lady beetles than traps placed at 1.50 m (20%) above ground; traps at 0.75 m above ground also detected the rarer species while the traps at 1.50 m above ground detected only the abundant species. Trap captures were higher during the noncotton season (November to April) compared with the cotton season (May to October). A significant positive correlation between cotton aphid abundance during the growing season and H. convergens abundance during the following noncotton season was also detected, indicating a significant movement of H. convergens from cotton to the periphery of the farm to seek refuge after cotton termination.     

Effect of Tribolium castaneum (Coleoptera: Tenebrionidae) nutritional environment, sex, and mating status on response to commercial pheromone traps

Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), the red flour beetle, is an important cosmopolitan pest of stored grains. Commercial traps baited with the synthetic aggregation pheromone 4,8-dimethyldecanal (DMD) are used to monitor T. castaneum population densities in storage facilities. However, trap catches may depend on several intrinsic and extrinsic factors. In this study, we explored the effects of beetle nutritional environment, sex, and mating status on the response of T. castaneum to commercial Storgard Dome traps. Beetles raised on a low-nutrition diet were 1.7 times more likely to enter DMD-baited traps compared with beetles that were raised on a high-nutrition diet. Although no sex difference in trap response was found, unmated beetles of both sexes were more responsive to DMD than were mated beetles, and this effect was especially pronounced for beetles reared on a low-nutrition diet. These results suggest that estimating T. castaneum population densities based on trap catches might be improved by incorporating information about the nutritional quality of infested stored products.     

SPLAT-OrB reveals competitive attraction as a mechanism of mating disruption in oriental beetle (Coleoptera: Scarabaeidae)

This study compared the efficacy of SPLAT-OrB, a new pheromone formulation for oriental beetle mating disruption that can be mechanically applied, with hand-applied plastic dispensers in commercial blueberry fields. Both formulations were tested at 2.5 and 5 g of the major sex pheromone component (Z)-7-tetradecen-2-one per hectare, and evaluated by measuring trap shut-down, mating success of caged females, and the number of grubs in sentinel blueberry pots baited with tethered females. All pheromone-treated plots had fewer male captures in traps and lower mating success of caged females compared with untreated plots. SPLAT-OrB, and plastic dispensers at the higher rate, also reduced the number of grubs in sentinel pots. To understand the mechanism of mating disruption in oriental beetle, males were observed approaching the pheromone sources in disrupted plots. In addition, male oriental beetle captures were quantified in plots treated with varying SPLAT-OrB dollop densities per ha. Consistent with predictions for competitive attraction, field observations revealed males approaching the pheromone source and male captures decreasing concavely with increasing dollop density. In a mark-release-recapture study, male oriental beetles responded to SPLAT-OrB dollops and plastic dispensers at least 60 m from the source. Additionally, SPLAT-OrB emitted pheromone that was attractive to male oriental beetles for >5 wk; however, emission rates and attraction dropped rapidly during the first 3-4 wk. This study demonstrates the feasibility of using SPLAT-OrB for oriental beetle mating disruption as an alternative to hand-applied plastic dispensers, and conclusively reveals that a principal mechanism is the competitive attraction of males.     

Effect of trap type, trap position, time of year, and beetle density on captures of the redbay ambrosia beetle (Coleoptera: Curculionidae: Scolytinae)

The exotic redbay ambrosia beetle, Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae), and its fungal symbiont Raffaellea lauricola Harrington, Fraedrich, and Aghayeva are responsible for widespread redbay, Persea borbonia (L.) Spreng., mortality in the southern United States. Effective traps and lures are needed to monitor spread of the beetle and for early detection at ports-of-entry, so we conducted a series of experiments to find the best trap design, color, lure, and trap position for detection of X. glabratus. The best trap and lure combination was then tested at seven sites varying in beetle abundance and at one site throughout the year to see how season and beetle population affected performance. Manuka oil proved to be the most effective lure tested, particularly when considering cost and availability. Traps baited with manuka oil lures releasing 5 mg/d caught as many beetles as those baited with lures releasing 200 mg/d. Distributing manuka oil lures from the top to the bottom of eight-unit funnel traps resulted in similar numbers of X. glabratus as a single lure in the middle. Trap color had little effect on captures in sticky traps or cross-vane traps. Funnel traps caught twice as many beetles as cross-vane traps and three times as many as sticky traps but mean catch per trap was not significantly different. When comparing height, traps 1.5 m above the ground captured 85% of the beetles collected but a few were caught at each height up to 15 m. Funnel trap captures exhibited a strong linear relationship (r2 = 0.79) with X. glabratus attack density and they performed well throughout the year. Catching beetles at low densities is important to port of entry monitoring programs where early detection of infestations is essential. Our trials show that multiple funnel traps baited with a single manuka oil lure were effective for capturing X. glabratus even when no infested trees were visible in the area.     

Optimal pheromone trap density for mass trapping cacao mirids

Sahlbergella singularis Haglund and Distantiella theobroma (Distant) (Heteroptera: Miridae) are the key insect pests of cacao in Ghana and elsewhere in West Africa. Since 1954, spraying with synthetic insecticides has been the principal means of controlling these pests. In West Africa, environmental concerns, economic stimuli, and unreliable access to insecticides have stimulated interest in ecologically more benign mirid control strategies as an alternative to a total reliance on insecticides. Males of both mirid species, and those of the less damaging Bryocoropsis laticollis Schumacher, respond to the same synthetic sex pheromone blend, so pheromone‐based strategies may provide control as well as monitoring opportunities. Pheromone traps were deployed for 3 months at nine densities between two and 30 traps per 0.1 ha plot (20–300 traps ha^?1) plus an untreated control treatment in a replicated large‐scale field experiment on mature mixed Upper Amazon hybrid cacao in Ghana, in order to determine the optimal dispenser density for mass trapping, lure‐and‐kill, and/or lure‐and‐infect. At the end of the trapping period, mirid populations in the various treatments were assessed by insecticide knockdown on 400 trees and by searches to hand height on 1 200 trees, together with an assessment of mirid damage. In total 781 S. singularis and 235 D. theobroma were captured in the pheromone traps. The optimal dispenser density for S. singularis was 150 traps ha^?1. Over 300 traps ha^?1 was probably optimal for D. theobroma as a smaller proportion of the population was captured, and numbers caught per trap displayed no decline with increasing trap density. From insecticide knockdowns, mirid population density was estimated at 220–230 ha^?1, 63% of which were D. theobroma. Too few pods and orthotropic shoots were damaged by mirids to establish the efficacy of pheromone trapping for mirid control.     

Factors affecting male Prays oleae (Lepidoptera: Yponomeutidae) captures in pheromone-baited traps in olive orchards

Effects of trap design, height and side of trap placement on olive trees, pheromone doses in dispensers, aging of dispensers in the field, and secondary pheromone components were evaluated for the development of an effective pheromone monitoring system for Prays oleae (Bernard) Lesne (Lepidoptera: Yponomeutidae) in olive orchards. Field trials showed that trap design, pheromone dose, and trapping side affected male captures, whereas dispenser age, trap height, and secondary components had no influence. Pherocon 1C and Delta traps baited with 1 mg of (Z)-7-tetradecenal captured more male moths than Pherocon II or Funnel traps. Placement of traps at different cardinal directions significantly affected captures, but this trend was not consistent and varied with flight period and trap position internal or external to the tree canopy. Moth phenology as determined by pheromone traps from early April to mid-October was consistent with published field data. Results indicate that Pherocon 1C or Delta traps baited with 1 mg of (Z)-7-tetradecenal provide an effective tool for monitoring the flight activity of P. oleae and the time of application of control measures.     

Effects of trap type, placement and ash distribution on emerald ash borer captures in a low density site

Effective methods for early detection of newly established, low density emerald ash borer (Agrilus planipennis Fairmaire) infestations are critically needed in North America. We assessed adult A. planipennis captures on four types of traps in a 16-ha site in central Michigan. The site was divided into 16 blocks, each comprised of four 50- by 50-m cells. Green ash trees (Fraxinus pennsylvanica Marshall) were inventoried by diameter class and ash phloem area was estimated for each cell. One trap type was randomly assigned to each cell in each block. Because initial sampling showed that A. planipennis density was extremely low, infested ash logs were introduced into the center of the site. In total, 87 beetles were captured during the summer. Purple double-decker traps baited with a blend of ash leaf volatiles, Manuka oil, and ethanol captured 65% of all A. planipennis beetles. Similarly baited, green double-decker traps captured 18% of the beetles, whereas sticky bands on girdled trees captured 11% of the beetles. Purple traps baited with Manuka oil and suspended in the canopies of live ash trees captured only 5% of the beetles. At least one beetle was captured on 81% of the purple double-decker traps, 56% of the green double-decker traps, 42% of sticky bands, and 25% of the canopy traps. Abundance of ash phloem near traps had no effect on captures and trap location and sun exposure had only weak effects on captures. Twelve girdled and 29 nongirdled trees were felled and sampled in winter. Current-year larvae were present in 100% of the girdled trees and 72% of the nongirdled trees, but larval density was five times higher on girdled than nongirdled trees.