Solitary

In most insect orders, adult size has a strong genetic component and growth is strongly determinate. In many Lepidoptera, for example, final adult size is relatively constant within a species; reduction in food quality or availability delays caterpillar growth rather than causing reduced final adult size, although there are exceptions. In contrast, in flies that have limited or ephemeral larval resources, such as a dung pat or temporary pool, cessation of larval growth would result in death as the habitat shrinks. Thus larval crowding and /or limitation of food supply tend to shorten development time and reduce final adult size. In some mosquitoes and midges, success in short-lived pool

Fig. 6.14 Solitary and gregarious females of the migratory locust, Locusta migratoria (Orthoptera: Acrididae). The solitaria adults have a pronounced pronotal crest and the femora are larger relative to the body and wing than in the gregaria adults. Intermediate morphologies occur in the transiens (transient stage) during the transformation from solitaria to gregaria or the reverse.

Fig. 6.14 Solitary and gregarious females of the migratory locust, Locusta migratoria (Orthoptera: Acrididae). The solitaria adults have a pronounced pronotal crest and the femora are larger relative to the body and wing than in the gregaria adults. Intermediate morphologies occur in the transiens (transient stage) during the transformation from solitaria to gregaria or the reverse.

(nymph), and large-sized adult with large hind femora. As densities increase, induced in nature by high survivorship of eggs and young nymphs under favorable climatic conditions, graded changes occur and a darker-striped nymph develops to a smaller locust with shorter hind femora. The most conspicuous difference is behavioral, with more solitary individuals shunning each other's company but making concerted nocturnal migratory movements that result eventually in aggregations in one or a few places of gregarious individuals, which tend to form enormous and mobile swarms. The behavioral shift is induced by crowding, as can be shown by splitting a single locust egg pod into two: rearing the offspring at low densities induces solitary locusts, whereas their siblings reared under crowded conditions develop into gregarious locusts. The response to high population density results from the integration of several cues, including the sight, odor, and touch of conspecifics (perhaps mainly via cuticular hydrocarbons acting as contact primer pheromones and detected by the antennae), which lead to endocrine and neuroendocrine (ecdysteroid) changes associated with developmental transformation.

Under certain circumstances biotic effects can override growth factors. Across much of the eastern USA, 13- and 17-year periodic cicadas (Magicicada spp.) emerge highly synchronously. At any given time, nymphal cicadas are of various sizes and in different instars according to the nutrition they have obtained from feeding on the phloem from roots of a variety of trees. Whatever their growth condition, after the elapse of 13 or 17 years since the previous emergence and egg-laying, the final molt of all nymphs prepares them for synchronous emergence as adults. In a very clever experiment host plants were induced to flush twice in one year, inducing adult cicada emergence one year early compared to controls on the roots of single-flushing trees. This implies that synchronized timing for cicadas depends on an ability to "count off" annual events - the predictable flush of sap with the passing of each spring once a year (except when experimenters manipulate it!).

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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