Biotic effects

habitats is attained by a small proportion of the larval population developing with extreme rapidity relative to their slower siblings. In pedogenetic gall midges (section 5.10.1), crowding with reduced food supply terminates larva-only reproductive cycles and induces the production of adults, allowing dispersal to more favorable habitats.

Food quality appears important in all these cases, but there may be related effects, for example as a result of crowding. Clearly, it can be difficult to segregate out food effects from other potentially limiting factors. In the California red scale, Aonidiella aurantii (Hemiptera: Diaspididae), development and reproduction on orange trees is fastest on fruit, intermediate on twigs, and slowest on leaves. Although these differences may reflect differing nutritional status, a microclimatic explanation cannot be excluded, as fruit may retain heat longer than stems and leaves, and such slight temperature differences might affect the development of the insects.

The effects of crowding on development are well understood in some insects, as in locusts in which two extreme phases, termed solitary and gregarious (Fig. 6.14), differ in morphometrics, color, and behavior. At low densities locusts develop into the solitary phase, with a characteristic uniform-colored "hopper"

a ft

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.

Get My Free Ebook


Post a comment