Lrs

398 In the nocturnal tenebrionid beetle Parastizopus armaticeps, the entire eye is able to detect polarized light. However, in many diurnal insects, especially Odonata, Hymenoptera, Coleoptera, Diptera, and Lepidoptera, the region of sensitivity is generally restricted to the dorsal part of the eye, the dorsal rim area (Labhart and Meyer, 1999). Within this region, the ommatidia are distinctly adapted to analyze the plane of polarization. The adaptations may include: (1) a fan-shaped arrangement of ommatidia within the eye, providing a wide angle of sensitivity; (2) pore canals in the corneas and irregular (as distinct from hexagonal) facets to increase light scattering; and (3) wider and shorter but very straight rhabdoms, lack of screening pigment between adjacent ommatidia, and highly specific orientation of the microvilli on the inner margins of the retinular cells, all of which increase sensitivity (Homberg and Paech, 2002). Within an ommatidium, there are two sets of rhabdomeres; the microvilli of one set are at 90° to those of the other set. The photosensitive molecules are arranged very precisely in the microvilli so as to absorb light maximally when the light waves oscillate parallel to the long axis of the microvilli. However, among different taxa the nature of the photoreceptive pigment may differ: in Orthoptera it is blue-sensitive, in Coleoptera green-sensitive, and in Hymenoptera and Diptera UV-sensitive. For additional information on the detection and use of polarized light by insects, see Wehner (1984, 1992, 1997), Rossel (1993), and Labhart and Meyer (1999).

Beekeeping for Beginners

Beekeeping for Beginners

The information in this book is useful to anyone wanting to start beekeeping as a hobby or a business. It was written for beginners. Those who have never looked into beekeeping, may not understand the meaning of the terminology used by people in the industry. We have tried to overcome the problem by giving explanations. We want you to be able to use this book as a guide in to beekeeping.

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