颜色对梨小食心虫产卵选择性的影响

梨小食心虫(Grapholitha molesta Busck)是一种重要的果树害虫,早春产卵喜在桃嫩梢叶上,为探明寄主颜色在其产卵选择中的作用,利用彩色卡纸模拟寄主颜色,室内比较了红、粉红、浅粉、橙黄、深黄、浅黄、青绿、深绿、浅绿、蓝、紫、褐色等12种不同颜色基质对其成虫产卵选择性的影响。结果发现:基质颜色对梨小食心虫的产卵选择性有显著影响,其产卵偏嗜浅黄和浅绿色,白色和黑色参比时其产卵选择率分别依次为68.9%、63.8%和64.1%、65.5%,蓝和浅粉色则表现一定的拒避作用,白色和黑色参比时其产卵选择率分别依次为47.7%、40.4%和47.2%、42.7%,且参比色对其产卵选择性影响差异显著。基质颜色对其产卵量亦有显著性影响,无论黑或白色参比,黄、绿颜色上的产卵量均较多,尤其是深黄、深绿和青绿色。基质颜色对1—7日龄梨小食心虫成虫的产卵选择性均有显著影响。白色参比时,2、3日龄蛾对浅绿和浅黄色的产卵选择率显著高于其他颜色;黑色参比时,2日龄时明显偏嗜浅绿色(79.7%),6日龄时明显偏嗜浅黄色(74.8%)。表明寄主颜色在梨小食心虫产卵场所选择中具有重要作用,为其卵期监测和防控中颜色应用乃至进一步揭示其产卵寄主选择机理提供了依据和参考。     

The role of beetle marks and flower colour on visitation by monkey beetles (hopliini) in the greater cape floral region, South Africa

BACKGROUND AND AIMS: A deviation from the classical beetle pollination syndrome of dull-coloured flowers with an unpleasant scent is found in the Greater Cape Floral Region of South Africa. Here, monkey beetles (Scarabaeidae) visit brightly coloured, odourless flowers with conspicuous dark spots and centres (beetle marks). The role of flower colour and markings in attracting monkey beetles is still poorly understood. METHODS: Artificial model flowers with different marking patterns were used to test the effect of beetle marks on visitation by monkey beetles. To test whether monkey beetles are conditioned to the colour of the local matrix species, model flowers of different colours were placed in populations of three differently coloured species of Iridaceae. KEY RESULTS: Among all three matrix species the presence of dark markings of some kind (either centres or spots) increased visitation rates but the different matrix species differed in whether the effect was due to a dark centre or to dark spots. Monkey beetles were not conditioned for the colour of the matrix species: model colour was not significant in the Hesperantha vaginata and in the Romulea monadelpha matrices, whereas yellow model flowers were preferred over orange ones in the orange-flowered Sparaxis elegans matrix. CONCLUSIONS: This study is the first to demonstrate that beetle marks attract pollinating monkey beetles in the Greater Cape Floral Region. In contrast to plants with the classical beetle pollination syndrome that use floral scent as the most important attractant of pollinating beetles, plants with the monkey beetle pollination syndrome rely on visual signals, and, in some areas at least, monkey beetles favour flowers with dark beetle markings over unmarked flowers.     

Adult movements of newly introduced alien Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) from non-host habitats

Mark-release-recapture experiments were undertaken in order to investigate the movement of adult Diabrotica virgifera virgifera LeConte from accidental introduction points towards suitable habitats, such as its host plant, Zea mays L. In Hungary in 2003 and 2004, nine mark-release-recapture experiments were carried out in a grass steppe area and lucerne field, in which two small maize fields (10x10 m) had been planted 300 m distant from the central release point. After each release of 5500 to 6000 marked D. v. virgifera, beetle recaptures were recorded three times using non-baited yellow sticky traps placed on 30, 105, 205 and 305 m radii around the release point. In seven out of 15 recapture periods (47%), beetle populations showed no directional movements, and their movements towards any particular habitat cannot be predicted. During five recapture periods (33%), beetle populations showed a uni-directional movement, and in three cases (20%) a bi-directional movement was observed. In 10 out of 15 recapture periods (67%), the released populations moved in a direction that was comparable with the mean wind direction during these periods; thus, beetle movements were slightly correlated with wind direction. On average over sites and years, beetles were not preferentially moving towards the two small maize fields (located 300 m from the release point) compared to other directions. However, beetles moved significantly more frequently in the direction of naturally-occurring maize fields within a radius of 1500 m than towards other habitats. Beetles stayed more frequently within flowering lucerne fields out to a radius of 300 and 600 m than in non-flowering lucerne or other habitats. On average, 2.8% (SD 3.2) of all recaptured beetles arrived in one of the two small maize fields located 300 m from their release point indicating that there is a high risk of a founder population establishing. Habitat management cannot be suggested as a means of preventing the beetle's initial dispersal because movement was usually non-directional, and alternative food plants were used prior to reaching maize.     

Red oilseed rape? The potential for manipulation of petal colour in control strategies for the pollen beetle (Meligethes aeneus)

The pollen beetle (Meligethes aeneus) is a major pest of oilseed rape (Brassica napus) at the inflorescence stage and is well known to prefer colours called yellow by human observers over many other colours. While commercial cultivars of oilseed rape have yellow flowers, little is known about the potential to manipulate host plant location and reduce subsequent infestation by this pest through variation in flower colour. We investigated the responses of pollen beetles to flowers of a white-petalled oilseed rape variety that had been dyed different colours in semi-field arena and field experiments. Flowers dyed blue or red were less heavily infested than those dyed yellow or the white flowers, indicating that blue and red flowers were less attractive than yellow and white ones. This response was most likely due to differences in petal colour because olfactometer studies showed that beetle responses to the odours of the coloured treatments did not differ. The comparatively high infestation of untreated white flowers is interpreted as a consequence of their high UV reflectance; the presence of a UV receptor in M. aeneus is suggested, and its role in visually guided insect–plant interactions in this species described. The potential for manipulation of petal colour in control strategies for the pollen beetle is discussed.     

Colour choice behaviour in the pollen beetle Meligethes aeneus (Coleoptera: Nitidulidae)

The pollen beetle Meligethes aeneus Fabricius (Coleoptera, Nitidulidae), a pest of oilseed rape (Brassica napus), is known to respond to coloured stimuli; however, current understanding of the underlying mechanisms of colour choice in this species is limited. In the present study, physiological and behavioural experiments are conducted to determine the response of the pollen beetle to colours in the field. Spectral sensitivity is measured in 10 animals using the electroretinogram technique. Light flashes (100 ms) at varied wavelengths (340–650 nm, 10‐nm steps) and at different light intensities are applied to the eye after dark adaptation. In behavioural experiments in the field, 100 water traps of varying colours (from yellow to green to blue with varying amounts of white and black added, and with known spectral reflectance) are set out on a bare soil field in May 2008. The mean spectral sensitivity curve of M. aeneus peaks at 520 nm; however, a model template fitted to the long wavelength tail of the observed curve reveals a peak at approximately 540 nm (green). A secondary sensitivity peak is observed in the ultraviolet (UV) range (370 nm). A total of 2482 pollen beetles are captured in the coloured traps. The results show that the pollen beetles' preference for yellow over other colours can be modelled as a colour opponent mechanism (green versus blue); however, further experiments are needed to specify responses to colours with higher UV reflectance. These findings may be used to optimize trap colours for monitoring to help develop integrated pest management strategies for pollen beetle control.     

Responses to olfactory and visual cues by over-wintered and summer generations of the pollen beetle, Meligethes aeneus

Abstract.  Behavioural responses to odours of oilseed rape in bud and flower stage and to green and yellow colours are studied for the two main phenological stages of pollen beetles, Meligethes aeneus , a major pest of oilseed rape, Brassica napus . Over-wintered individuals oviposit in buds of oilseed rape. Adults of the new generation (i.e. the summer generation) feed on flowers of different plant species before over wintering. In olfactometer experiments, the over-wintered beetles display a higher preference for odour of oilseed rape at the bud stage compared with the summer generation, both with and without colour stimuli. Flower odours are preferred in combination with yellow colour. Colour stimuli presented alone do not affect the behaviour. The summer generation beetles respond to both bud and flower odour. Adding colour stimuli changes the summer generations preference towards yellow and flower odour.     

Flight take-off performance of Colorado potato beetle in relation to potato phenology

The flight take-off frequency of adult Colorado potato beetles, Leptinotarsa decemlineata (Say), from potato plants, Solanum tuberosum L. 'Red Pontiac' at the bloom stage of development was 2.2-2.5-fold that of Colorado potato beetle from plants at the vegetative stage. Tests were conducted in a flight chamber over a period of 3 h. Prefeeding Colorado potato beetles for 48 h on potato plants at the bloom or at the vegetative stage before placing them into the flight chamber resulted in the same significantly higher flight take-off frequency from potato plants at the bloom stage than from plants at the vegetative stage. These results demonstrate that the factor in potato plants in bloom that stimulates the flight take-off of the Colorado potato beetle is independent of the feeding history of the beetles and begins acting only when the beetles are in the presence of the plant. According to these results, the dispersal of adult Colorado potato beetles from potato fields in bloom to younger potato fields with plants at the vegetative stage, previously reported in the literature, is at least partly explained by the effect of plant phenology on the frequency of flight take-off. Results confirm the value of planting potato fields of similar phenology over as wide an area as possible to reduce Colorado potato beetle dispersal between fields. Results also imply that staggering the planting dates of conventional potato refuge areas near Colorado potato beetle transgenic or conventionally resistant potato fields is a sound management practice, because it promotes the movement of wild beetles over to the adjacent younger resistant crops.     

Supergenes in polymorphic land snails. I. Partula taeniata.

The general colour of the shell in Partula taeniata is controlled by at least two loci. One of these (C) has a series of six alleles which determine the yellow (Y) and neutral brown (N) series of colours. Alleles for darker colours are dominant to those for lighter colours, but dominance is not always complete. The pink (P) colours are determined by a second locus (P) which modified the expression of the lighter alleles of the C locus. Orangeshell colour segregates with yellow but its allelic relationship is unknown. Colour of the lip is controlled by a locus (L) with pink lip dominant to white lip. The colour of the spire is determined by a locus (S) with dark (N4) spire dominant to light spire. An intermediate spire colour shows the same pattern of inheritance and may represent the effect of another allele. Banding of the shell is dominant to absence of bands, with two loci (B1 and B2) determining the type of banding. An allele at B1 produces the frenata pattern; an allele at B2 produces zonata; together they produce lyra. All the loci for which linkage data are available are linked so strongly that the whole array may be considered a supergene. Self-fertilisation takes place primarily during early reproductive life. About 20 per cent of the young of the first mating of an individual are produced by selfing, but over the whole reproductive span the frequency is only about 2-5 per cent. There is inconclusive evidence for heterozygote advantage of banded individuals.     

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.     

Flight behavior of methyl-parathion-resistant and -susceptible western corn rootworm (Coleoptera: Chrysomelidae) populations from Nebraska

Relative flight behavior of methyl-parathion-resistant and -susceptible western corn rootworm, Diabrotica virgifera virgifera LeConte populations, was studied as part of a larger effort to characterize the potential impact of insecticide resistance on adult life history traits and to understand the evolution and spread of resistance. A computer interfaced actograph was used to compare flight of resistant and susceptible individuals, and flight of resistant individuals with and without prior exposure to methyl-parathion. In each case, mean trivial and sustained flight durations were compared among treatments. In general, there were few differences in trivial or sustained flight characteristics as affected by beetle population, insecticide exposure, sex, or age and there were few significant interactions among variables. Tethered flight activity was highly variable and distributions of flight duration were skewed toward flights of short duration. Tethered flight activity was similar among resistant and susceptible beetles with the exception that susceptible beetles initiated more flights per beetle than resistant beetles. After sublethal exposure to methyl-parathion, total flight time, total trivial flight time, and mean number of flights per resistant beetle declined significantly. Because long-range flight was uncommon, short- to medium-duration flights may play an important role in determining gene flow and population spread of resistant D. v. virgifera. These results suggest that organophosphate-resistant beetles can readily move and colonize new areas, but localized selection pressure (e.g., management practices) and exposure to methyl-parathion may contribute to the small-scale differences in resistance intensity often seen in the field.     

Wind as an abiotic factor of Colorado potato beetle (Coleoptera: Chrysomelidae) flight take-off activity under field conditions

The flight take-off activity of Colorado potato beetles, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), was significantly higher at a landscape-protected than at semiexposed and exposed sites in a 2-yr field study. In both years, mean daylight temperature, solar radiation, and relative humidity were generally similar at all sites, but wind speed was lower at the protected site than at the exposed sites. Results suggest that wind was the limiting abiotic factor for flight take-off at the exposed site. Caged beetles exposed to constant wind speeds of 3.4, 4.7, and 7.0 m/s showed a significant corresponding decrease in number of flight take-off. There was no cumulative effect of wind exposure on the readiness of the beetles to fly, suggesting that wind acts as a physical barrier to flight take-off. It should be possible to reduce Colorado potato beetle flight dispersal by selecting fields most exposed to wind over landscape-protected fields when rotating potato, Solanum tuberosum L., crops.     

Field-Cage Studies of Beauveria bassiana (Hyphomycetes: Moniliaceae) for the Suppression of Adult Western Corn Rootworm, Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae)

The efficacy of the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin, was tested as a control agent for adult western corn rootworm, Diabrotica virgifera virgifera LeConte, in walk-in field cages. Suspensions of B. bassiana conidia were applied to corn plants in cages into which laboratory-reared beetles had been released. Beetles were collected at 3 and 5 days post-application and evaluated in the laboratory for mortality. Mortality was 10, 29 and 50%, at rate equivalents of 7 X 10 12 , 2 X 10 13 (two applications), and 5 X 10 13 conidia/ ha, respectively. There was no significant difference in mortality of beetles collected at 3 days compared with 5 days post-application. Mortality due to B. bassiana was 24% when beetles were released into field cages 24 h post-application (5 X 10 13 conidia/ha) compared with 50% when beetles were present during the application. Beetle mortality declined significantly with increasing time from application in feeding assays carried out with leaf samples removed from plants at 0, 12, 24 and 72 h post-application. Mortality of beetles collected from treated plants within cages and maintained in the laboratory was found to overestimate the population decline by 10% when compared with beetle estimates from treated plants within field cages.     

Relationship between phenotypic traits and selected fitness components of Diabrotica virgifera virgifera

Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) is one of the most important and best-studied maize pests, yet little information is available regarding the basic relationships among its phenotypic traits, particularly those that reflect the overall fitness of this successful invader in Europe and North America. Such information is critical for studies on the invasiveness, behavioural ecology, and management of this pest. Phenotypic traits that change over the lifetime of the beetle were investigated (e.g., fresh body weight) as they can indicate changes in adult physiology or fitness of D. v. virgifera . Phenotypic traits that remain stable over the beetle's lifetime were also investigated (e.g., pronotum width, head capsule width, hind tibia length), as they most likely allow detection of genetic differences between populations. Furthermore, phenotypic traits were investigated that may best predict fecundity (e.g., fresh body weight, elytra width) and life span (e.g., elytra length), as these two factors influence the population growth of this highly invasive species. Finally, regression equations are provided for the age-specific oviposition and survival of the long-living D. v. virgifera adults, which may allow researchers to reduce the duration of their bioassays without losing information.     

Comparative flight behavior of Diabrotica virgifera virgifera and Diabrotica barberi in the laboratory

A tethered flight system was used to characterize and compare the flight behavior of western, Diabrotica virgifera virgifera LeConte (WCR), and northern, Diabrotica barberi (Smith and Lawrence) (NCR), corn rootworms in the laboratory. Distributions of flight durations were skewed towards short flights for both species regardless of sex or age and there was high variability in flight durations and frequency in individual beetles. Flight distributions for WCR were distinctly bimodal, reflecting a dichotomy between short trivial flights and much longer sustained flights. Trivial flight performance did not vary with age but did differ between species. In comparison to WCR, NCR took shorter flights but had a higher frequency of flights over a 23-h period. Overall, WCR beetles logged substantially more flight time in the same period of time. The proportion of individual WCR undertaking sustained flight was relatively low (<24%) and, for females, declined along with sustained flight durations as a function of age. Periodicity of trivial flight did not differ betweer the species. In general, flight activity was greatest during early morning and early evening hours. No correlations were found between any feature of flight performance and body size or wing loading ratios.

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Résumé Un système de vol captif a été utilisé pour caractériser et comparer au laboratoire les comportements de vol de D. virgifera virgifera et D. barberi. La distribution des durées de vol est nettement biaisée avec la grande majorité des vols durant moins d'une minute quels que soient le sexe et l'âge. Il y a une grande variabilité interindividuelle tant en durée qu'en fréquence de vol. Les distributions des durées de vol en fonction du sexe sont bimodales chez D. virgifera virgifera, mais pas chez D. barberi, ce qui reflète la séparation entre vols brefs ordinaires et long vols prolongés. Les vols brefs ordinaires ne dépendent pas beaucoup de l'âge ou du sexe mais diffèrent suivant l'espèce. D. barberi a eu des vols plus brefs, mais en a effectué plus pendant une période de 23 heures. Au total, D. virgifera virgifera a consacré nettement plus de temps au vol pendant la même période; mais, chez cette espèce la proportion d'individus effectuant des vols soutenus était relativement faible (<24%), avec une diminution de leur nombre avec l'âge chez les femelles; le nombre le plus élevé étant chez les jeunes femelles. La périodicité des vols ordinaires n'a dépendu ni du sexe, ni de l'espèce; l'activité de vol a été en général plus importante tôt le matin et en début de soirée. Aucune corrélation n'a été trouvée entre une quelconque performance de vol et la taille du corps ou la charge alaire.

     

Features effective in course control during object fixation by walking Colorado beetles

A test paradigm is designed to determine which features of viewed objects (a disk 10° in diameter) are responsible for preferential fixation by Colorado beetles (Leptinotarsa decemlineata). The beetle walks on a locomotion compensator that permits free choice of direction in a visual surround containing three different objects. The beetles use both colour and contrast information in these choice experiments. The preferred colours are yellow and orange; their attractiveness is considerably enhanced when they appear in a pattern with highly contrasting features such as stripes. In its optimal form, the object amounts to a dummy beetle, with a pattern that resembles the markings on the elytra of this species. Since the beetles appear to employ a contact pheromone for sex recognition, the function of orientation to these patterns is unclear. However, the patterns might accelerate the identification of conspecifics or be effective at a distance. The reaction to the dummies is telotactic — that is, the beetles walk towards the dummy. One other object, a 10°-wide black stripe, elicits menotactic orientation, in which the beetle maintains a stable course at an angle to the object.     

Effect of temperature and diet on hind wing colouration development and elytral hardness of adult Colorado potato beetle (Coleoptera: Chrysomelidae)

The effects of food and temperature on the development of colour pigment in the hind wings of adult Colorado potato beetle, Leptinotarsa decemlineata (Say), were investigated. In a replicated study, adults were held at 18°C, 28°C and 18/28°C on potato foliage (Solanum tuberosum L.), potato tubers, or without food in controlled-environment chambers. Representative subsamples of wings were collected at two-day intervals, mounted on microscope slides, and photographed to document the progression of colour change. Observations were also made on elytral hardening over time. Hind wing colour developed more quickly at 28°C than at 18°C, and after three weeks had attained a deeper red colour at the higher temperature. Colour development was also more rapid when adult beetles were fed on foliage compared with tubers. In foliage-fed beetles, elytra hardened more quickly at 28°C than 18°C, and many tuber-fed beetles never developed hardened elytra, regardless of temperature treatment. Unfed beetles developed no hind wing colour pigment and their elytra remained soft for the duration of the experiment. Colour plates documenting wing colour development over time are presented; variation in colour development under the conditions tested, suggests that the use of hind wing colouration to estimate beetle age in the field may be problematic.     

Optimising coloured pan traps to survey flower visiting insects

Colour is an important attractant for many flower-visiting insects (anthophiles). Consequently, coloured pan trapping is an efficient technique that can be easily and cost-effectively used to quantitatively sample assemblages of anthophiles. However, colour preferences of anthophiles is an important source of bias that needs to be considered in pan trap surveys. By drawing sub samples comprised of different colour combinations from a database of pan trap surveys in the lowlands of the Cape Floristic Region, we examine the effects of colour on pan trap catches and determine which combinations of colours might provide better estimates of diversity when sampling with multi-colour sets of pan traps. Pan trap catches included the major groups of anthophiles in the region (Coleoptera, Diptera and Hymenoptera), but butterflies (Lepidoptera) were strongly under-represented. Colour played an important role in determining the species richness and composition of pan trap catches, with colour sets that included high reflectance yellow and white generally having catches with the highest species richness. While all colour combinations provided reasonable estimates of proportional species richness, proportional abundance of taxa varied among different colour sets, and did not accurately reflect actual proportions of different taxa in the entire dataset. For comparative biodiversity surveys and assessments we recommend the use of high reflectance colours such as white and yellow traps, while for full inventory surveys, it may be necessary to include other colours to catch rarer species that are excluded by the high reflectance colours alone.     

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.     

Intraspecific variation of flower colour and its distribution within a sea lavender, Limonium wrightii (Plumbaginaceae), in the northwestern Pacific Islands

Differentiation of flower colour is thought to be one of the most important factors promoting plant speciation. We describe the intraspecific variation of flower colour and its distribution in Limonium wrightii. We conducted a survey on 36 islands in the northwestern Pacific and discriminated six morphs of flower colour variation. Two flower colour morphs, pink and yellow, were most frequently observed, and their geographical distributions were basically allopatric. These two morphs were in contact in a narrow zone on Okinoerabu Island, located in the middle region of the Ryukyu Archipelago. In addition, orange, white, and ivory flower morphs were also found in this zone. The geographical distribution of pink and yellow morphs showed a “leapfrog” pattern; the distribution of pink flowers was divided into two areas, intercalated by the distribution of the yellow flower morph. The orange morph may have resulted from hybridization between the pink and yellow flower morphs.     

Spectral preference and temporal modulation of photic orientation by Colorado potato beetle on a servosphere

The Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), is a diurnal insect that strongly relies on visual cues to guide its walk. In the present study, we investigated the orientation behavior of non‐diapausing walking CPB in response to emissive colors produced by light emitting diodes (LEDs) in a dual choice arena adapted to a servosphere, where the only illumination available came from the photo‐stimuli. Our results demonstrate that CPB show positive phototactic behavior when stimulated with different wavelengths of light; they preferred to orient towards white (420–775 nm), ultraviolet (UV) (351 nm), blue (472 nm), green (570 nm), yellow (585 nm), orange (590 nm), and red (660 nm) over darkness when both alternatives were offered, but no orientation responses were elicited by infrared (940 nm). Both males and females preferred yellow and green over other colors, but did not show any particular preference between them, thus correlating with their preference for wavelengths reflected by vegetation. Sexual differences were noted in that male CPB preferred white over either red or UV, whereas female CPB did not show any preferences when offered these colors. Female CPB preferred UV and blue over red, whereas males showed no preferences when these colors were offered. Colorado potato beetles turned at higher angles and performed more tortuous walks in complete darkness and when infrared vs. darkness were offered compared with the rest of the colored lights. Both sexes preferred continuous over pulsed yellow light. Colorado potato beetles subjected to pulsed yellow light showed a temporal alteration of their walking performance by walking less, slower, and turning at a higher rate. The results are discussed with regard to the role of color in the CPB attraction to host plants and conspecifics as well as the role of intermittent photic stimuli in their orientation behavior. The information provided here provides a basis for the improvement of trapping devices for detection and survey of incipient or invasive CPB, and development of alternate control strategies for this important pest of potatoes and other solanaceous crops.