During our analyses of hemolymph propulsion in Anopheles gambiae, we observed periodic ventral abdominal contractions and hypothesized that they promote extracardiac hemolymph circulation in the abdominal hemocoel.
Instead, hemolymph circulation in the thoracic and abdominal hemocoel is primarily controlled by the contractile action of the heart.
Furthermore, within the context of hemolymph circulation, the relative importance of abdominal contractions has been fiercely debated.
Hemolymph circulation in mosquitoes is primarily controlled by the contractile action of a dorsal vessel that runs underneath the dorsal midline and is subdivided into a thoracic aorta and an abdominal heart.
While the precise function of abdominal contractions continues to be debated, it has repeatedly been shown that they alter hemolymph pressure in the hemocoel [20], [24], [25], [26], and thus, have been hypothesized to function in hemolymph circulation, thermoregulation, development, and active ventilation [23], [27], [28], [29], [30].
However, using synchrotron X-ray imaging Westneat et al. showed in Coleoptera, Hymenoptera and Orthoptera that body movements and hemolymph circulation cannot by themselves account for the cyclic compression and expansion of tracheoles [31].
After mathematically estimating the force of individual heart and abdominal contractions in lepidoteran and coleopteran pupa, Sláma concluded that the dorsal vessel is a weak organ incapable of propelling hemolymph against a pressure gradient, and postulated that the abdomen is the primary driver of hemolymph circulation [22], [28].
Additional indirect evidence supporting the connection between abdominal contractions and hemolymph circulation includes the finding that allatropin and serotonin modulate both abdominal and heart contractions in the moth, Pseudaletia unipuncta [19].
The present study continues to expand our understanding of hemolymph circulation in mosquitoes, and provides insights into the forces that disseminate nutrients, hormones, and immune factors to all regions of the body, and the physiological interactions between pathogens and mosquitoes.
The pressure from the cover slip affects the A7 dorsal cluster, most probably because of the disruption of normal hemolymph circulation.
