Attraction of first instar larvae of Spodoptera litura to different colours was studied to determine those that could be used as effective visual attractants for trapping the larvae during dispersal. The larvae were presented with cones of coloured paper. Each cone was placed in the center of a 15-cm Petri dish around the edge of which the larvae were released. Percentage of larvae arriving at the cone was recorded at 5-min intervals over a 15-min period. Differences in the percentages reflected differences in larval attraction to the different colours. The larvae were highly attracted to Foliage Green, Green Bice and Cadmium Yellow. The larvae arrived at the Scarlet Red, Ultramarine Blue, Gray, Orange, White and Black cones in percentages that were almost equal, but lower than at the Foliage Green, Green Bice and Cadmium Yellow cones. Arrival of larvae at the coloured cones increased with time, but their relative preference for different colours remained the same. This study shows that green and yellow can be used as visual attractants in Spodoptera litura larval traps.
An image recognition system can be based on a single-layer neural network composed of Min/Max nodes. This principle is easy to use for greyscale images. However, this article deals with the possibilities of utilising neural nets for colour image recognition. Several principles are demonstrated and tested by recently developed software. A new modified Min/Max node Single Layer Net, suitable for recognition in HSV (Hue Saturation Value) colour space, is presented in this paper.
The coexistence of discrete morphs within a species, with one morph more conspicuous than the other(s) is often thought to result from both sexual selection and predation. In many damselflies, sexual dimorphism occurs jointly with multiple female colour morphs. Typically, one morph is coloured like the male (andromorph), while the other(s) is not (gynomorph(s)). The mechanisms contributing to the maintenance of such female polymorphism in damselflies remain poorly understood, especially the role of predation. We tested the detectability of two different female colour morphs of the damselfly, Enallagma cyathigerum, using human observers as model predators; andromorphs were detected more frequently than gynomorphs. Field data on mortality of males and the two different female morphs due to predation or drowning were also collected, and these observations support morph-specific mortality. In natural populations predation risk was higher in males than females; gynomorphs, however, were more prone to predation than andromorphs. Differences in behaviour between morphs, rather than colour, may explain this result.
Článek představuje problematiku synestézie jako percepčního fenoménu. V první části jsou popsány základní projevy a specifika synestézie (automatičnost, konstantost, idiosynkratičnost). V druhé části se článek věnuje otázce vzniku synestézie a s tím souvisejících teorií vývoje lidské percepce („neonatal synaesthesia“, „cross-modal-transfer“, „interactive specialization approach“). Třetí část je zaměřena na problematiku tzv. „jazykových synestézií“, tedy synestézií, kde je v roli spouštěče jazyková jednotka (písmeno, slovo, číslice), a ukazuje, jak může výzkum synestézie souviset s (psycho) lingvistickým bádáním. V poslední části textu je představen aktuální kanadsko-český projekt a jeho základní hypotézy.
We determined if mature ladybirds use colour to initially find suitable host plants. We also determined whether ladybird beetles are capable of associating characteristics such as colour with the presence of prey. Here, we show that the multicoloured Asian ladybird beetle, Harmonia axyridis, has a differential response to yellow compared to green colours. Naive ladybirds, of both sexes, make significantly more visits and spend more time on yellow vs. green coloured pillars. After pairing yellow and green colours with the presence or absence of aphid prey, ladybirds alter their foraging behaviour. Beetles conditioned to having food on both pillar colours exhibited the same responses as naive beetles, while beetles conditioned to only yellow or green pillars did not exhibit a preference for visiting or spending time on different colours. However, there was a trend towards females spending more time on pillar colours on which they received reinforcement, and males spending more time foraging on colours opposite to that which they were reinforced. Thus, H. axyridis is capable of responding to cues such as colour, and its foraging behaviour can be altered as a result of prior experience.
Social wasps are often considered as nuisance pests in urban environments and are often controlled by using traps. The majority of commercially produced traps for catching wasps have yellow as the dominant colour around the trap entrance. However, the observations on the function of yellow as an attractant for wasps are controversial. The efficiency of yellow, compared with green striped (N = 15) and yellow and green striped beer traps (N = 15) was evaluated. According to the results, yellow does not have a specific role as an attractant for wasps of the genera Vespula Linnaeus and Dolichovespula (Rohwer). For wasps, it may be the bait that is the major lure and it might be sufficient on its own for both control and monitoring purposes.