Let's not jump to the conclusion that fat bodies and hemolymph are somehow disconnected from each other. 
 
From Scientific American, regarding hemolymph:
 
...Insects and other invertebrates, on the other hand, have what is called hemolympha heterogeneous fluid that courses through their bodies, bathing all the internal tissues. Hemolymph is mostly water, but it also contains ions, carbohydrates, lipids, glycerol, amino acids, hormones, some cells and pigments. 
 
....hemolymph thus flows freely throughout their bodies, lubricating tissues and transporting nutrients and wastes. Whereas the vertebrate circulatory system serves primarily to carry oxygen throughout the body, insects respire an entirely different way namely, through tracheal tubes.
 
...Insects do have hearts that pump the hemolymph throughout their circulatory systems.

 
Insect tracheal system
 
From my own studies:   In essence, it's almost impossible to separate internal from external factors in insects.    By this, I mean that insects have a tracheal system that opens to the exterior via spiracles and reaches every cell of the body.  
 
Many authors talk about the tracheal system as the respiratory system, comprised of a complex network of tubes, that deliver oxygen-containing air to EVERY CELL of the body.  What is forgotten is that the hemolymph carries everything to every cell and opens directly to the exterior of the insect.  That's vastly different from mammalian lungs.  
 
From a 2010 Review of the Fat Body:   (https://www.researchgate.net/publication/41807175_Morpho-physiological_analysis_of_the_insect_fat_body_A_review ).
  
The insect fat body is the main organ of the intermediate metabolism of insects. The majority of proteins of the haemolymph is synthesized in this tissue, which also presents the functions of lipids, carbohydrates and proteins storage. This tissue is also responsible for the synthesis of vitellogenins, proteins with an important role in the reproduction of the insects, being incorporated into the oocytes during vitellogenesis. 


So, my question to the list - how does one separate the fat body from the hemolymph?  The fat bodies need raw materials to synthesize proteins, and the synthesized proteins have to be delivered to cells.

I have not had the privilege of being able  to listen to one of Samuel's lectures.  From the perspective of a mite, proteins are available in the hemolymph and in the  fat body.  Maybe it's like eating cake - you get the cake in the hemolymph, but you get the cake and the frosting in the fat body.  From the perspective of the insect, the impact of feeding on the hemolymph versus feeding on the fat body should be the similar in some ways, and differ significantly in others.

We've all seen mites on bees in places other than over the fat bodies.  If fat body feeding is the norm, does every mite succeed at feeding at the five star restaurant, or do some mites have to settle for the local diner?  If not all mites succeed in accessing the protein rich food source, what happens to the others? 

Is there such a thing as feeding dominance?  Going back to my Ph.D. research on feeding and mating in insects (e.g. grasshoppers), the lesson learned was that some individuals are more successful in finding the best food, some are the most successful in mating, and some excel at both.  At the time, reporting plasticity of behavior, differences by insect individuals, bucked the trend to consider invertebrate individuals to be some form of auto-bot, genetically programmed to do the same thing every time.  We now know better, and more recent work suggests that mites may demonstrate similar individual differences in behaviors and successes.  



 




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