Abstract:
A study was undertaken to establish the pattern and level of lipid utilization in third stage infective
larvae (L 3 ) of Haemonchus contortus under temperature and moisture stress conditions. The stress factors were
representative of an arid and semi arid site in Kenya. The L 3 were subjected to gradual increase and reduction
in temperature and moisture, respectively, using a programmable cold/heat testing chamber. Optical density
per area (Corrected average pixels) derived from image analysis of individual stained larvae using an image
analysis software (UN SCAN IT gel (r) ), were used to estimate the lipid content of larvae subjected to different
stress treatments. It was observed that lipid content of the L 3 declined and was negatively correlated with
duration of exposure with significantly (p = 0.012) lower rates in moisture compared to temperature stressed
L 3 . It was also observed that the decline occurred in phases signifying possible adaptive physiological process
aimed at preserving lipid reserves and viability. During revival, there was a drastic decline in lipid reserves
probably as a result of increased lipid utilisation by the reviving larvae. The epidemiological significance of
these findings in field larvae is discussed.
