Effect on Activity and Dispersal

Through its effect on metabolic rate, temperature clearly will affect the activity of insects. Many of the generalizations made above with regard to the influence of temperature on development have their parallel in relation to activity. Thus, there is a range of temperature within which activity is normal, though this range may vary among different strains of the same species. The temperature range for activity is correlated with a species' habitat; for example, in the Arctic, chironomid larvae are normally active in water at 0°C, and adults can fly at temperatures as low as 3.5°C (Downes, 1964).

By affecting an insect's ability to fly temperature may have a marked effect on a species' dispersal and, therefore, its distribution. Further, because flight is of such importance in food and/or mate location and, ultimately, reproduction, temperature is of great consequence in determining the abundance of species. Insects use various means of raising their body temperature to that at which flight is possible even when the ambient temperature is low. For example, they may be darkly colored so as to absorb solar radiation, or they may bask on dark surfaces, again using the sun's heat. Some moths and bumblebees beat their wings while at rest and simultaneously reduce hemolymph circulation in order to increase the temperature of the thorax (Chapter 17, Section 3.1). A dense coat of hairs or scales covers the body of some insects, which, by its insulating effect, will retard loss of heat generated or absorbed.

In extremely cold climates these physiological, behavioral, or structural features may no longer be sufficient to enable flight to occur, especially in a larger-bodied, egg-carrying female. Thus, different temperature-adaptation strategies are employed, some of which are exemplified especially well by Arctic black flies (Simuliidae: Diptera). Typical adult temperate-climate species are active insects that mate in flight, and females mayfly considerable distances in search of a blood meal necessary for egg maturation. In contrast, females of Arctic species seldom fly. Their mouthparts are reduced and eggs mature from nutrients acquired during larval life. Mating occurs on the ground as a result of chance encounters close to the site of adult emergence. In two species parthenogenesis has evolved, thereby overcoming the difficulty of being found by a male (Downes, 1964).

Temperature change, through its effect on the solubility of oxygen in water, may markedly modify the activity and, ultimately, the distribution and survival of aquatic insects. Members of many aquatic species are restricted to habitats whose oxygen content remains relatively high throughout the year. Such habitats include rivers and streams that are

658 normally well oxygenated because of their turbulent flow and lower summer temperature, and high-altitude or -latitude ponds and lakes, which generally remain cool through the

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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