Visual orientation of the black fungus gnat,Bradysia difformis,explored using LEDs

Fungus gnats occur worldwide with more than 1 700 described species. They can cause serious damages on ornamentals, crop plants, and edible mushrooms, and are considered to be a serious pest in the last years. Bradysia difformisFrey (Diptera: Sciaridae) represents a common species in Europe. Usually, yellow sticky traps are used for monitoring and control in greenhouses and fluorescent tube‐based light traps are additionally applied for control in mushroom cultivation. The importance of such visual trapping measures for efficient monitoring or alternative control increases in biological and integrated plant protection. However, detailed color preferences of fungus gnats are mostly unknown. We studied the visual orientation of B. difformis with light‐emitting diodes (LEDs) in a broad range of peak wavelengths from 371 nm (ultraviolet, UV) to 619 nm (amber). We determined attractive wavelengths in consecutive choice experiments in daylight and darkness. Highest numbers of adult B. difformis were attracted to UV radiation (382 nm) followed by green‐yellow light (532–592 nm). The responses to UV and the green‐yellow range were relatively unspecific and mostly independent from intensity. Combination of UV and yellow LEDs improved trapping efficacy compared to a single UV or yellow LED trap, as well as compared to a common yellow sticky trap. When both wavelengths were compared to a black surface to increase contrasts, the black surface was preferred over yellow, but was less attractive than UV. Thus, B. difformis displays two, probably wavelength‐specific, behaviors to UV radiation and green‐yellow light, with UV being the most attractive stimulus. These behaviors might be directly related to underlying photoreceptors, suggesting dichromatic vision in B. difformis.     

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.     

6种颜色粘虫板对春季菜地昆虫的诱集效应

为筛选对春季蔬菜害虫具有较好诱集效果的粘虫板,促进蔬菜害虫绿色防控技术的研究与推广,采用红色、黄色、绿色、蓝色、白色和黑色6种颜色的市售粘虫板对菜地昆虫进行诱集试验.结果显示,粘虫板诱集的害虫以尖眼蕈蚊Bradysia minpleuroti、小菜蛾Plutella xylostella、端大蓟马Megalurothrips distalis和黄蓟马Thrips flavus为优势种;黄曲条跳甲Phyllotreta striolata、南美斑潜蝇Liriomyza huidobrensis、灰地种蝇Delia platura、棉蚜Aphis gossypii、小绿叶蝉Empoasca flavescens、菜粉蝶Pieris rapae为常见种.试验中蓝色粘虫板诱集的灰地种蝇的数量显著高于其它处理组(P<0.05);黄色粘虫板诱集的南美斑潜蝇、棉蚜、小绿叶蝉的数量显著高于其它处理组(P<0.05);蓝色和白色粘虫板诱集的端大蓟马、黄蓟马的数量显著高于其它处理组(P<0.05);蓝色粘虫板诱集到的尖眼蕈蚊的数量显著低于其它处理组(P<0.05).各种颜色粘虫板诱集昆虫的益害比较低,诱集益虫总数仅占诱集昆虫总数的1.64％,表明该时段使用粘虫板防治菜地害虫,对益虫伤害较小,对保护利用天敌昆虫具有重要意义.本研究结果为科学使用粘虫板防治菜地害虫提供理论依据.     

An experimental test of a visual-based push–pull strategy for control of wood boring phytosanitary pests

1 International phytosanitary standards require mandatory fumigation for key wood boring beetle pests prior to export. Pressure to reduce the use of toxic fumigants has created a need for alternative control techniques.
2 A visual based push–pull strategy that exploits a differential attraction to yellow and ultra violet (UV) lights was tested for its efficacy at controlling Cerambycidae.
3 The relative attraction of four 'push' lighting treatments [two yellow (high and low-pressure Sodium), one white (metal halide) and a control (no light)] to beetles was assessed. Highly attractive UV 'pull' traps were compared with a paired control trap, the difference used as a measure of the UV traps attractiveness to residual beetles attracted by 'push' lights.
4 Trap catch beneath the two yellow 'push' lights was more similar to the control (no light) treatment than the white light for both species. Control 'push' lights had the highest average catch of Arhopalus ferus , whereas white light was least attractive. This finding was counter intuitive to expectations, and potential mechanisms are discussed. The white 'push' light was most attractive to Prionoplus reticularis.
5 Ultraviolet 'pull' traps were highly attractive to residual beetles drawn to yellow 'push' light treatments. Relative attraction to the UV 'pull' traps beneath control and white 'push' lights differed between species.
6 The results obtained suggest that a push–pull strategy combining yellow site lighting with UV kill traps could provide site specific control of wood borers. Future research should attempt large-scale trials that are subject to competing alternative stimuli at a wood processing site.     

Yellow Traps Can Be Used to Monitor Populations of Coccinella transversalis (F.) and Adalia bipunctata (L.) (Coleoptera: Coccinellidae) in Cotton Crops

During 1992–4, square (30 times 30 cm) sticky traps of various colours were used on a commercial cotton farm to trap adults of Coccinella transversalis and Adalia bipunctata which are both major predators of Helicoverpa spp. Both insects were attracted most to yellow traps which also reflected the most visible light between 500 nmand 600 nm(where green foliage reflects most light). When yellow was diluted with white to produce yellow-white hues, the light reflected between 500 nm and 600 nm was reduced and the numbers of C. transversalis and A. bipunctata adults caught on these traps were also significantly reduced. This suggests that C. transversalis and A. bipunctata adults can discriminate foliage-like hues (500–580 nm) from non-foliage-like hues (<500 nm and >580 nm) and are attracted to colours that suggest the foliage of host plants that may harbour their prey. Yellow sticky traps placed 25–50 cm above ground caught significantly more C. transversalis and A. bipunctata adults than those placed at 75–150 cm and are the most appropriate traps to monitor populations of C. transversalis and A. bipunctata adults in cotton farms.     

瓢虫的趋光性反应研究

以六斑月瓢虫Menochilus sexmaculata Fabricius和狭臀瓢虫Coccinella transversalis Fabricius为例,研究了瓢虫对不同光质(波长)的趋光性反应。在室内分别测定了六斑月瓢虫和狭臀瓢虫对5种发光二极管(LED)光波的趋性,以及在田间挂板(佳多)测定了瓢虫对色板的选择趋性。室内测定结果表明,瓢虫对黄色和白色LED光波的选择趋性显著高于与其它颜色;田间挂板试验表明,黄色对瓢虫的诱杀作用最强。综合分析,黄色对瓢虫有强烈的吸引作用,建议在使用黄板进行田间监测和防治时应考虑对天敌瓢虫的诱杀作用。     

Insect colour preference compared to flower colours in the Australian Alps

An apparent predominance of plant taxa with pale flowers in the alpine floras of Australia and New Zealand may be due to the prevalence of insects, such as flies, that prefer pale colours and the absence of other types of potential pollinators that are attracted to bright colours such as social bees and birds. In this study, the diversity of flower colours, and the preference of insects for different colours were examined for the largest contiguous alpine area in Australia, around Mt Kosciuszko. Out of an alpine flora of 204 taxa, 127 species were found to have large showy flowers. The most common flower colour among these taxa was white (53.5%), then yellow (21.3%), followed by pink (6.3%), and cream (6.3%). Only a handful of taxa had red, blue, brown, green, orange or purple flowers. When the colour preference of insects was tested using five different coloured traps (white, yellow, orange, red and purple), the most successful traps were white then yellow, with these two colours accounting for 66% of all individual insects collected. Diptera were the most common insects caught (576 insects greater than 4 mm in length, 31 morphotaxa) showing an apparent preference for white and yellow coloured traps over others. Therefore, the results add some support to the proposition that the 'white' flora of the Australian Alps may be associated with the colour preference of flies, which have previously been found to be the most common type of pollinators in the Kosciuszko alpine zone.     

Attraction of stink bugs to rocket traps with different combinations of wing and landing board color

The stink bugs, Halyomorpha halys and Riptortus pedestris, are two of the most economically important pests of leguminous crops and fruits in Korea. Here we present the results from a field monitoring test that evaluated the effect of variation in rocket trap type and color on stink bugs captures. We tested various types of rocket traps, along with wing combinations and landing boards of various colors. The test was run in soybean fields in Miryang, Korea. We developed a modified rocket trap intended to enhance the capture efficacy of stink bugs. We evaluated traps including (1) yellow rocket trap with a solar fan and blue LED lamp, (2) a yellow trap with solar fan but no light, (3) rocket traps with black, green, yellow, white, red, brown, and blue color stimuli, (4) different color combinations of trap wings, and (5) traps with a landing board were evaluated. Our results showed that yellow winged rocket traps with solar fans and blue LED lamps attracted significantly more stink bug species than other traps, in both soybean fields. Use of these improved traps such as a yellow trap with a solar fan and blue LED lamp, and a yellow trap with a solar fan would therefore enhance the monitoring and capture of stink bugs in diversified agro-ecological landscapes. The potential use of traps with a specific hue, combination of features, and modifications to monitor stink bugs accurately is discussed. Continuing improvements to traps to meet the demands of a changing pest landscape and agricultural mechanization are needed.     

Spectral composition of light sources and insect phototaxis,with an evaluation of existing spectral response models

Artificial illumination attracts insects, but to what extent light attracts insects, depends on the spectral composition of the light. Response models have been developed to predict the attractiveness of artificial light sources. In this study we compared attraction of insects by existing light sources used for streetlights as well as newly developed environment friendly alternatives, and used this data to test the predictive ability of the existing response models. Light sources differed in overall attractiveness to insects and relative attractiveness was dependent on insect order. The attraction patterns predicted by the two models correlated weakly with the number of insects attracted when the only light source rich in UV, a mercury vapour light, was included in the tested spectra. When the mercury vapour light, which is going to be banned in Europe, was not included in the test no correlation was found between predicted and observed attraction patterns. We conclude that currently existing attraction response models are insufficiently sensitive to evaluate new light sources.     

The role of odour and visual cues in the pan-trap catching of hoverflies (Diptera: Syrphidae)

Coloured pan traps are frequently used to attract and catch insects, such as in the monitoring of populations of beneficial insects in classical or conservation biological control. They are also used in the evaluation of the recovery of insect populations after disturbance and in many other situations where an estimate of relative insect numbers is required. However, the fact that traps may be visible to the insects over a considerable distance can influence the interpretation of catch data. This difficulty may arise, for example, if traps along a transect can attract insects from some or all of the other transect positions. This study compared the effect of different coloured traps on attraction and catch of hoverflies. The hypothesis was that completely yellow traps would attract hoverflies from a distance, while traps that were green outside and yellow inside would catch fewer flies because only those from above or near the trap can see the yellow stimulus. A subsidiary hypothesis was that rose water would enhance hoverfly capture rates. For the two main hoverfly species captured, Melanostoma fasciatum (Macquart) and Melangyna novaezelandiae (Macquart), significantly more individuals were caught in completely yellow traps than in yellow and green or in completely green traps. Moreover, the addition of rose water increased the number of hoverflies caught significantly. It is suggested that if a measure of hoverfly numbers relating to a particular distance along a transect is required, consideration should be given to the ability of hoverflies to see yellow traps from a distance. The use of traps that are green outside would more accurately reflect the local abundance of hoverflies. If higher trap catches of hoverflies are needed for statistical purposes, rose water can enhance catches.     

Density and distribution of soybean aphid,Aphis glycines Matsumura (Hemiptera: Aphididae) in response to UV radiation

Increasing ultraviolet radiation (UV) has led to greater interest in its current and potential effects on organisms, including herbivorous insects. Here we report the short-term effects of UV on soybean aphids (Aphis glycines Matsumura), a common phytophagous pest of soybeans. We used two complementary approaches to examine how modifying UV radiation affects this phloem-feeding herbivore via changes to soybean aphid densities and their within plant distribution. We found that artificially adding UV in a lab setting decreased soybean aphid population size compared to a low UV control; however, blocking UV radiation in the field had minimal effects on aphid density. Further observations suggest that soybean aphid location could mediate UV effects; feeding on the underside of leaves may shield aphids from some harmful effects of UV. Our results demonstrate the potential importance of UV to insect herbivores and how behavior may influence such effects.     

Sticky trap monitoring of a pest–predator system in glasshouse tomato crops: are available trap colours sufficient?

Monitoring of pest presence and population development in the crop during the season is essential for integrated pest management. Although many tools, for instance coloured sticky traps, have been developed, the full advantage of available information is rarely taken into account in decision‐making. The reasons behind include high workload in practice but also the poorly studied relationships between trap catches and populations in the crop. Here, we investigate whether commercially available coloured sticky traps can be used as tool to monitor population densities of a pest–predator system in glasshouse tomato. The response of Macrolophus pygmaeus (Rambur) (Hemiptera, Miridae) to blue and yellow sticky traps was tested in laboratory and glasshouse experiments. The results indicate that M. pygmaeus can be monitored equally well with both trap colours. The number of trapped insects showed good correlation with the population densities on the crop. Under growing conditions, more M. pygmaeus were trapped on blue compared with yellow sticky traps. However, due to the known preference of Trialeurodes vaporariorum (Westwood) (Hemiptera, Aleyrodidae), yellow traps should be used for a combined pest–predator monitoring.     

Light emitting diode(LED)‐based trapping of the greenhouse whitefly (Trialeurodes vaporariorum)

Visual traps like yellow sticky card traps are used for monitoring and control of the greenhouse whitefly (Trialeurodes vaporariorum). However, reflected intensity (brightness) and hence, attractiveness depend on the ambient light conditions, and the colour (wavelength) might not fit with the sensitivity of whitefly photoreceptors. The use of light emitting diodes (LEDs) is a promising approach to increase the attractiveness, specificity and adaptability of visual traps. We constructed LED‐based visual traps equipped with blue and green high‐power LEDs and ultraviolet (UV) standard LEDs according to the putative spectral sensitivities of the insects' photoreceptors. In a series of small‐scale choice and no‐choice recapture experiments, the factors time of day as well as light intensity and light quality (colour) of LED traps were studied in terms of attractiveness compared to yellow traps without LEDs. Green LED traps (517 nm peak wavelength) were comparably attractive in no‐choice experiments but clearly preferred over yellow traps in all choice experiments. The time of day had a clear effect on the flight activity of the whiteflies and thereby on the trapping success. Blue LEDs (474 nm) suppressed the attractiveness of the light traps when combined with green LEDs suggesting that a yet undetected photoreceptor, sensitive for blue light, and an inhibiting interaction with the green receptor, might exist in T. vaporariorum. In choice experiments between LED traps emitting green light only or in combination with UV (368 nm), the green‐UV combination was preferred. In no‐choice night‐time experiments, UV LEDs considerably increased whitefly flight activity and efficacy of trapping. Most likely, the reason for the modifying effect of UV is the stimulating influence on flight activity. In conclusion, it seems that the use of green LEDs alone or in combination with UV LEDs could be an innovative option for improving attractiveness of visual traps.     

Efficient monitoring of maize orange leafhopper, <Emphasis Type="Italic">Cicadulina bipunctata</Emphasis> (Hemiptera: Cicadellidae), and small brown planthopper, <Emphasis Type="Italic">Laodelphax striatellus</Emphasis> (Hemiptera: Delphacidae), in forage maize fields using yellow sticky traps

The monitoring of insect pests in fields of forage maize is difficult because plants are tall and grow at a high density. We investigated the effectiveness of colored sticky traps and appropriate conditions for monitoring insect pests in forage maize fields. Large numbers of the maize orange leafhopper, Cicadulina bipunctata Melichar (Hemiptera: Cicadellidae), and the small brown planthopper, Laodelphax striatellus Fallen (Hemiptera: Delphacidae), were collected during the experimental period with yellow and blue sticky traps placed in summer crop forage maize fields. A greater number of insects were trapped in yellow traps relative to blue traps. Traps located at a lower height (40 cm above the ground) attracted larger numbers of C. bipunctata, whereas L. striatellus did not demonstrate a height-dependent preference. These results indicated that yellow-colored sticky traps located at low height are effective for collecting C. bipunctata and L. striatellus simultaneously. Seasonal occurrence data obtained by the yellow sticky traps showed clearer seasonal occurrences than that obtained by two previously developed methods, suction and light traps, indicating that sticky traps are effective for monitoring the seasonal occurrence of these two insects in forage maize fields.     

Modelling selection for resistance to methods of insect pest control in combination

The development of resistance to insecticides is now widespread among insects. Other methods of pest control are also potentially at risk of encountering resistance. A modelling approach is presented here to evaluate the effects of combining methods of insect pest control on the selection for resistance to the control methods. This analysis is based on partitioning the total mortality acting on a population into its constituent components from all known sources, and these are related to selection for resistance. When two control methods are used in combination, selection for resistance against the two is a linear function if the two don't interact, otherwise it may be sublinear or supralinear. A specific example is presented using a model of the Olive fruit fly (Dacus oleae Gmel.) and employing food-baited and pheromone-baited traps for control. The control methods that appear least likely to encounter resistance are natural enemies and the use of pheromone traps for male annihilation. These should be integrated into a control program where possible to minimize the development of resistance to other control methods being used.     

中国红树林生态系统主要害虫种类、 防控现状及成灾原因

红树林湿地是中国东南沿海的关键生态系统之一。近年来, 我国红树林陆续出现多种害虫种群暴发成灾的现象, 使红树林湿地的可持续利用面临严重挑战。本文归纳了近20年来中国红树林生态系统的主要害虫种类, 危害较严重的有海榄雌瘤斑螟Acrobasis sp., 毛颚小卷蛾Lasiognatha cellifera, 丽绿刺蛾Latoia lepida, 白囊袋蛾Chalioides kondonis, 蜡彩袋蛾Chalia larminati和小袋蛾Acanthopsyche subferalbata等; 对红树林虫害的防控现状进行总结, 目前开展的防控工作主要以生物农药、 昆虫生长调节剂、 昆虫天敌等生物防治方法为主, 结合灯光诱杀等物理防治手段的运用, 对暴发期的害虫种群可以取得较好的控制效果; 并从红树林生态系统健康水平和昆虫群落多样性等方面对害虫种群的成灾原因进行初步探讨; 最终提出以虫害可持续控制为目标的红树林生态系统生境调控策略, 以期为提高红树林湿地虫害管理水平以及促进红树林的可持续发展提供重要的理论参考和科学指导。     

Temporal response and attraction of Diaphorina citri to visual stimuli

As the vector of the global disease of citrus greening or huanglongbing, Asian citrus pysllids, Diaphorina citri Kuwayama (Hemiptera: Liviidae), are the greatest threat to the worldwide citrus industry. Critical to management of D. citri and huanglongbing is optimization of surveillance methodologies. Although phytophagous insects may find host plants by multimodal cues, some appear to primarily use visual cues. In this study, we examined the behavior of Asian citrus psyllids toward light from light‐emitting diodes (LEDs) in the insect visible spectrum. The periodicity of attraction of psyllids to visual cues was evaluated in the field (yellow sticky traps) and laboratory (multi‐colored LEDs) with a strong peak of activity during the afternoon in both the field and the laboratory (both 14:00 to 18:00 hours). In laboratory evaluations of psyllids to differently colored LEDs, strongest attraction was to LEDs emitting ultraviolet (390 nm), green (525 nm), and yellow (590 nm) light. Male and female psyllids did not differ significantly in their responses to visual cues. These findings provide the basis for formulating better traps that reflect UV and yellow light and potentially incorporate UV LEDs for monitoring psyllids and a better understanding of Asian citrus psyllid visual behavior.     

Habitat heterogeneity affects predation of European pine sawfly cocoons

Habitat heterogeneity is thought to affect top‐down control of herbivorous insects and contribute to population stability by providing a more attractive microhabitat for natural enemies, potentially leading to reduced population fluctuations. Identifying the parameters that contribute to habitat heterogeneity promoting top‐down control of herbivorous insects by natural enemies could facilitate appropriate management decisions, resulting in a decreased risk of pest insect outbreaks because of a higher level of predation. In our study, we measured the top‐down pressure exerted by small mammals on the cocoons of a notorious pest insect in pine forests, the European pine sawfly (Neodiprion sertifer), which is known to be regulated by small mammal predation. The forest stands used differed in heterogeneity measured in terms of differences in tree diversity and density, understory vegetation height, presence/absence, and density of dead wood. We found higher predation in more dense spots within forest stands. Further, the effect of dead wood on sawfly cocoon predation depended on the pine proportion in forest stands. The addition of dead wood in a manipulation experiment had a slight positive effect on cocoon predation, while dead wood removal caused a clear decrease in predation rate, and the decrease was more pronounced when the proportion of pine increased. Our results show that habitat heterogeneity affects predation by generalist predators on herbivorous insects. This knowledge could be applied to reduce the risk of insect outbreaks by applying management methods that increase heterogeneity in perennial systems such as forests and orchards, thus decreasing the levels of insect damage.     

Ultraviolet light-emitting diode (UV LED) trap the West Indian sweet potato weevil, <Emphasis Type="Italic">Euscepes postfasciatus</Emphasis> (Coleoptera: Curculionidae)

The West Indian sweet potato weevil Euscepes postfasciatus (Fairmaire) is a troublesome pest insect of sweet potato that originally came from the Caribbean, but is now expanding its distribution into the Pacific Islands. Although sterile insect techniques have been used against this pest in a demonstration experiment on Kume Island [Ohno et al. (2006) Kontyu to Shizen 41:25–30], effective methods of monitoring E. postfasciatus are scarce. It is necessary to detect the weevils at an early stage of invasion in uninvaded areas, and an attractant trap can be used to achieve this. Thus, we developed an ultraviolet (UV) light-emitting diode trap, invented a method for diffusing the light to attract more insects, and investigated the attractiveness of the light trap to E. postfasciatus under laboratory conditions. Our results indicate that diffused UV light has a higher potential to attract E. postfasciatus than direct UV light. Furthermore, sweet potato is an effective bait to use to capture the weevils attracted by UV light. Thus, E. postfasciatus can be trapped using diffused UV light and sweet potato bait.     

Kairomone attractant for the leafmining fly, Liriomyza bryoniae (Diptera, Agromyzidae)

A field test carried out in an industrial greenhouse in Lithuania revealed the attractiveness of synthetic methyl salicylate (MeSa) towards an economically important leafmining tomato pest, Liriomyza bryoniae (Kaltenbach) (Diptera, Agromyzidae). The behavioural reaction of the flies depended very much on the simultaneous presence of both olfactory and visual stimuli. The attractiveness depended on the colour of a sticky trap: MeSa attracted significantly more flies (ca. 2.2 times) when placed in yellow traps than in aluminium foil colour ones, when catches in such traps were compared to a corresponding control. L. bryoniae is the first species within the Agromyzidae family attracted by MeSa. The attractant was attributed to kairomones, as the compound is known as a plant-produced volatile. MeSa can be an effective extra-tool for increasing the attractiveness of traps. It should be evaluated in future whether such trap/bait combination is effective for the mass trapping of L. bryoniae leafminers in greenhouses (closed area).