Meeting Abstract
93.4 Wednesday, Jan. 7 Losing the battle against fungal infection: suppression of termite immune defenses during mycosis ROSENGAUS, Rebeca*; AVULOVA, Svetlana; REICHHELD, Lindsey; Northeastern University; Northeastern University; Northeastern University r.rosengaus@neu.edu
The progression of Metarhizium anisopliae fungal infection on the cellular immune defenses of the dampwood termite Zootermopsis angusticollis was studied by quantifying the number and types of circulating hemocytes of naive nymphs and nymphs exposed to either a control suspension lacking conidia, 2×103, 2×106 or 2×108 conida/ml doses. Hemocyte density was monitored on days 1, 2, 3, 4, 7 post-exposure. Our results show that the density of prohemocytes and particularly plasmatocytes, but not granular hemocytes, changed as a function of both conidia dosage and time elapsed since exposure. The development of mycosis beyond the third day resulted in an almost complete collapse of plasmatocytes which coincided with the appearance of hyphal bodies in the hemolymph and the onset of sluggish behavior, culminating in termite death. Prophenoloxidase activity (PO), used as a proxy for estimating investment in immunity function, surged two to three days after exposure to a 108 conidia/ml and then waned to baseline values by day seven post exposure. Thus, the initial immune response in these termites is overtaken by M. anisopliae, mainly by destroying the hosts plasmatocytes and reducing PO activity that is necessary for the successful encapsulation of the invading fungus.
