p. 226 The digestive tract of flies has to cope with a variety of food sources. Often the same individual is feeding on both blood and nectar, so the interior has been divided into a series of distinct regions, for consuming and processing meals, then for nutrient absorption, and finally for excretion or waste removal, the length and size of the different parts varying with species and food type.”
p. 227 The mid gut has been poorly studied, which is quite remarkable considering how essential a good diet is to the fly. Flues, like us, have a variety of micro-organisms that live inside them to aid difestion. It has been suggested that the number … could be greater than the number of cells in their entire body… it is more than likely .. the larvae of the mosquito Aedes aegypytii don’t start off with any gut fauna and the poor things can’t actually grow if they are prevented from establishing a healthy microbe environment, cultured from microbes they would have consumed from their environment.
The midgut bacteria have been shown to strengthen the immune response in mosquiots and protect them against any unwelcome pathogens… The bacteria in the gut of adult Anopheles mosquitos inhibits Plasmodium infection – it alerts the immune system of the mosquito to let tit know that these parasites have arrived and the mosquito needs to do something about it, but these bacteria are also directly attacking the Plasmodum by producing enzymes and toxins. Studying which bacteria are the most effective at tackling this will aid our war against malaria. As mosquitos are smaller, and less complicated than us humans, they also make a great model for understanding the interactions between the host, the good bacteria and the bad pathogens.
p. 231 There are further issues to overcome when feeding. Mosquitos and other blood-feeding species have to cope with the high internal temperatures of their hosts … many blood-feeding species are heterothermic ie they vary between self-regulating their temperature and using the external environment to regulate it. The ANopheles genus does this by excreting fluid droplets from the end of their abdomens. This reduces the temperature of the internal fluid by a process of evaporative gooling, where the external air cools the fluid. This mechanism prevents all gut symbionts, as well as the mosquito, from overheating.
p. 278 Many species of fly will allow themselves to fall into a coma to protect themselves during times of extreme temperature… they can take their bodies below freezing point without all the internal cells becoming solid. This allows them to survive during periods of extreme cold, by inducing a state called a chill-coma. Some species have glycerol in their cells that acts as antifreeze. One such fly is Chymomyza constata… another species of drosophilid… subjected the largae of this species to a series of lower and lower temperatures.. (t) cryopreservation at -196C (-321F). And some survived – to be fair there was quite a high death rate in the individuals at -196C 0 but still, some survived, which means that these flies are the most complex animals able to do so.”
About