Simple approaches for environmental and mechanical management of the Varroa mite, Varroa destructor Anderson and Trueman (Parasitiformes: Varroidae), on the honey bee, Apis mellifera L. (Hymenoptera: Apidae) in Egypt

Background Varroa mite, Varroa destructor Anderson and Trueman (Parasitiformes: Varroidae), is an ectoparasitic mite of the honey bee, Apis mellifera L. (Hymenoptera: Apidae), with a great economic importance. It is the major deadlock of apiculture development all over the world. Results This work aimed to assess the effect of bee house and dark bee house on numbers of Varroa mite on white card board sheets, worker broods, and alive bees during spring and autumn of 2018 and 2019. Two types of card board for sticking the fallen Varroa mite were evaluated through winter of 2019. Keeping honey bee hives in a dark room during March and September of 2018 and 2019 for a successive 3 days resulted in a great reduction in the number of Varroa inner bee hive, i.e., on the white card board sheets, area of broods, and alive honey bee. Highest number of fallen Varroa mite on the white card board sheets was obtained in the case of using the dark bee house during March and September in 2018 and 2019, followed by keeping in a normal bee house then those fallen in the case of the open apiary. Conclusion The dark bee house grooming behaviour increased through 3 days of dark. Environmental management of bee house and dark bee house can be promising in colony collapse disorder. Modified adhesive sheets were more efficient in this regard than the normal ones.

Intentional and Incidental Visual Memory as a Function of Cognitive Level and Color of the Stimulus

Performance of two groups of youngsters, educable mentally retarded (CA 15-5; MA 11-4; IQ 74.3) and those of average ability (CA 10-5; MA 11-3; IQ 109.1) was compared for intentional and incidental visual memory as a function of cognitive level and color of the stimulus. Nonretarded subjects performed significantly better than the retarded ones of equal MA. Both groups performed better with a color than black-white card, and both groups did better on the tasks involving intentional rather than incidental memory.

On areal induction

In my paper “On the Relation of Artificial Colour-blindness to Successive Contrast,” I described a modification of some experiments by Sigmund Exner. A disc, half black and half white, with a very narrow slit at the junction of the two halves, revolves in front of an incandescent lamp. Another lamp throws a light upon the face of the disc. While it is rotating slowly, the incandescent filament of the lamp, seen through the slit as it passes across, looks bright against the white card, but when a certain velocity is reached it appears as a black thread against a brighter background.

XVII. Colour photometry.—Part II. The measurement of reflected colours

In our first paper on this subject we have shown how the luminosity of the spectra of various sources of light can be measured; and the present paper is an extension of the subject, dealing with the measurement of the light reflected from bodies in terms of the colours of the spectrum of the light illuminating them. By the method which we adopted in the first part of "Colour Photometry” this can be effected, and, indeed, we carried that out in several instances. The method then employed was very simple. If we wished to measure the illuminating value of the spectrum of light reflected from a metal, we placed it at an angle in front of the slit of the spectroscope, so as to reflect the light from the crater of the positive pole of the electric light through the photometer, and measured the luminosity of each part of the spectrum thus formed by the method we indicated in our paper. Again, in experimenting with Gorham’s discs, such as Maxwell employed, where it became necessary to determine the light reflected from the different coloured papers or cards used in the discs, the plan first adopted was to replace the receiving shadow screen of zinc oxide (see § VI) by the coloured papers, and again to make a luminosity measurement. This plan answered its purpose, but it was rather laborious. When two or three colours are combined by rotation to form a grey, and black and white sectors are combined to match that grey, in order to ascertain the total luminosity of each colour, the angular value of the sectors being known, it is necessary to refer the luminosity to that of some standard reflecting surface, which is naturally a white one. As the comparison light is coloured by falling on coloured paper, the value of the spectrum reflected from such paper could not by this first method be directly compared with that reflected from the white screen. In the case of a coloured screen, the curve of spectrum luminosity would therefore have to be reduced to that in which the comparison light was white. This difficulty was surmounted by making half the receiving screen white and half of the colour whose luminosity was to be measured, illuminating the shadow of the rod thrown on the coloured paper by the spectrum colour, and that thrown on the white card by the white light reflected from the surface of the first prism (§ XXVI). This did away with any reduction or calculation; but still an objection remained, as, for definite comparison, it was almost necessary that the same observer should always make the measurement.