Reproduction

C Aedes and other mosquitoes

FIGURE 19.8. (Continued)

subsequent studies have shown that in most species yolk is mainly of extraovarian origin, especially, the fat body (see below). In the ovary, JH has two effects: early in vitellogenesis it "primes" the follicular epithelial cells, while later it regulates the permeability of the follicular epithelial layer. In Rhodnius and Locusta, for example, JH causes the follicular epithelial cells to shrink slightly, resulting in the development of prominent intercellular channels (patency) (Davey et al., 1993; Davey, 1996). Vitellogenins have been shown to move along these channels, to be accumulated pinocytotically by the oocyte during vitellogenesis. The precise way in which JH stimulates the follicle cells to shrink remains unclear, though an effect on the arrangement of microtubules within the cells has been demonstrated. (Evidence from other non-insectan systems strongly implicates the involvement of these organelles in the regulation of cell shape.)

As was noted in Section 3.1.1, for most insects the source of most yolk components is extraovarian, specifically the hemolymph, which serves as a reservoir for materials synthesized in the fat body. In the early to mid-1960s, evidence was collected that suggested a

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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