Factors Initiating and Terminating Molt Cycles

Compared with the enormous volume of literature on the endocrine interactions that regulate growth and molting, relatively little is known about the external factors that initiate or terminate molting cycles.

A number of environmental variables have been shown to affect growth and molting, and some of these clearly exert their effect via the neurosecretory system, that is, they stimulate or depress the synthesis/release of hormones from the brain. Probably the best studied of these variables are feeding and photoperiod.

In the blood feeders Rhodnius and Cimex and in some sap-feeding Hemiptera, for example, Oncopeltus, whose food is highly consistent in nature, engorgement causes distension of the abdominal wall and initiates a molt cycle. Information from stretch receptors in the wall passes along the ventral nerve cord to the brain where neurosecretory cells are activated to release PTTH. In insects that feed more or less continuously through the stadium, also, the intake of food is probably an important stimulus for the release of neurosecretion. Locusta migratoria, for example, has stretch receptors in the wall of the pharynx, which are stimulated as food passes through the foregut. Information from the receptors reaches the

* The name derives from the fact that the gene (usp) producing this protein also has other developmental roles. When it malfunctions, in Drosophila, the larva develops an extra pair of posterior spiracles.

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