LIII hemocytes are sessile and quiescent but they are activated towards an exploratory behaviour at WPP, similar to the behaviour of embryonic hemocytes (Evans et al., 2010; Sampson and Williams, 2012a; Sampson and Williams, 2012b).
An average of 20 hemocytes per mosquito were scattered along the basal surface of both of these two organs, and a high proportion of these hemocytes were phagocytic.
One of them is Vn1.5, a short peptide of 14 amino acids required for the expression of Cotesia rubecula polydnaviruses in Pieris rapae host hemocytes and the following inactivation of these hemocytes [ 50].
Physical disturbance of these hemocytes results in their re-homing to this niche [ 41 ], suggesting the presence of attractive signals regulating developmental migrations post-embryogenesis.
Although oenocytoids cannot phagocytize bacteria, challenge with M. luteus also induced a significantly greater proportion of these hemocytes to melanize than E. coli (t-test; P < 0.01).
Our results suggest that integrins (more specifically myospheroid, Drosophila's main beta integrin subunit) and integrin-containing adhesions play no role in the original attachment of these hemocytes to the dorsal patches areas, thus indicating that alternative adhesions systems may also be involved in hemocyte attachment to these locations.
At least two of these hemocyte classes participate in the encapsulation of the wasp egg.
With respect to the pericardial diaphragm formed by pericardial cells present on either side of the cardiac tube, these hemocytes are located dorsally.
Moreover, ex vivo cell culture of LIII hemocytes with ecdysone generates similar migratory behaviour to WPP hemocytes, indicating that the ecdysone hormone induces hemocyte activation.
LIII +ecdysone hemocytes exhibited a dispersed exploratory behaviour similar to that of WPP cells (Fig. 2A, centre and right; supplementary material Movies 3 and 5) and these hemocytes presented an increased displacement ranging from 60 to 160 µm (Fig. 2A, right track plot).
