MFSc

The major objective of the research work is to study the
taxonomy, species diversity, host specificity, intensity of infestation,
length - weight relationship and reproductive biology of bopyrid
parasite infesting the genus Macrobrachium Bate, 1868 of the Cochin
region. Collections were taken from 3 stations Perumbavoor (Periyar
River) and Panangad (Vembanad lake) for a period of 13 months (July
2002 to July 2003) and Champakkara (Vembanad lake) for a period of
one year (October 2003 to September 2004). The study revealed that of
the five species of Macrobrachium inhabiting water bodies of Cochin
region, only two species were found infested with bopyrids.
Macrobrachium idella was infested with Palaegyge alcocki whereas M.
scabriculum with a new variety, P. alcocki var. novo cochinensis. This
shows that bopyrid infestation is species specific. Diagnostic characters
of both the parasite species are given in the text. Regarding the intensity
of infestation, prawns from the Perumbavoor region of Periyar River had
maximum infestation in comparison with other regions (Panangad and
Champakkara). The infestation during different months also revealed
the same trend. It indicates that infestation is more at the freshwater
region than at the estuarine region.
,
Relationships between length and weight of infested M. idella, P.
alcocki separated from the host, total length of host and parasite, total
length of male and female parasite, carapace length of the host and total
length of male as well as female parasite are all statistically significant.
. The study has brought out the ways of association of male and
female parasites as well as attachment of female parasite to the host.
Mature female parasite has been distinguished from the immature.
Fecundity studies revealed that the number of eggs produced by the
parasite ranges from 8148 (1 cm total length, 0.9 cm total width, 0.12 g

total weight) to 29,683 (1.2 cm total length, 1.0 cm total width, 0.168 g
total weight). Number of ova per milligram body weight ranged from
67.9 to 185.518 (126.709 average). Relationships between fecundity
and total length, total weight, total width and total weight of brood of the
parasite are all significant.
The chapter on reproductive biology reveals important
observations on marsupial brooding, ovulation, embryonic development
and incubation, hatching and epicaridea stage of P. alcocki. The last
chapter is on the effect of parasitism on the host. Here the aggressive
behaviour of infested host, parasitic castration, degeneration of gills and
secondary infections are dealt with in some detail.