Food Uptake And Utilization

body cells (e.g., Haunerland and Shirk, 1995). However, Braendle et al. (2003) showed that 505

in the pea aphid, Acyrthosiphon pisum, some mycetocytes originate from nuclei near the posterior end of the embryo while others may have their origin as nuclei in the middle of the embryonic central syncytium. Usually, the mycetocytes form specific structures known as mycetomes (bacteriomes) distinct from the fat body. The mycetocytes contain symbiotic bacteria (rarely, yeasts) for which various roles have been proposed (Douglas, 1989, 1998; Dixon, 1998). The mycetocyte system of aphids is particularly well studied. The primary bacterial symbiont is Buchnera aphidicola, which is inherited transovarially (from mother to daughters via the ovary). The number of mycetocytes in the host is fixed at birth (i.e., they do not divide), though the cells grow to about four times their original size during larval development as the bacteria multiply. For aphids there is strong evidence that the bacteria supply the host with essential amino acids. The bacteria may also participate in nitrogen recycling and upgrading (converting excretory nitrogen to useful materials) as suggested above for cockroaches. In aphids the evidence is against a role for the bacteria in the synthesis of vitamins and lipids (Douglas, 1998); however, this possibility cannot be ruled out for other insect groups. Curiously, and contrary to what is generally assumed, there is no known benefit to the bacteria from this association (Douglas, 1998).

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