Fecundity of Hoplopleura scapteromydis (Phthiraptera : Anoplura, Hoplopleuridae), ectoparasite of Scapteromys aquaticus (Rodentia : Muridae) in Rio de La Plata marshlands, Argentina
Gg. Liljesthrom et M. Lareschi, Fecundity of Hoplopleura scapteromydis (Phthiraptera : Anoplura, Hoplopleuridae), ectoparasite of Scapteromys aquaticus (Rodentia : Muridae) in Rio de La Plata marshlands, Argentina, J PARASITOL, 87(3), 2001, pp. 542-544
Density and age structure of Lice collected from captured Scapteromys aquat
icus rodents were studied to estimate the fecundity of Hoplopleura scaptero
mydis. The number of eggs with a visible embryo inside (E), nymphs (N), adu
lt males (AM), and adult females (AF) were recorded for each rodent. For th
e ith rodent, the fecundity of H. scapteromydis, F(i), was estimated as F(i
) = {[E(i) + N(i)]/2}/AF(i)/T, where T represents the period of preimaginal
development (unknown and arbitrarily considered as T = 1), and the sex rat
io of the preimaginal stages was supposed to be 1:1. In order to look for d
ensity-dependent effects, F(i) was plotted against AM(i), this being an ind
ependent estimation of infrapopulation density. The number BE rodents suita
ble for AF and AM calculations was 38 (57% of the parasitized animals). Alm
ost 95% had a low-to-moderate louse burden (1 < AM < 30) and were captured
every season, whereas only 3% had a heavy (61 < AM < 70, captured in winter
) or very heavy (AM > 80, captured in summer) louse burden. The extreme val
ues of F were 0.63 and 18 (1.3 and 36 if both sexes were considered). High-
to-moderate F-values (F > 5) were estimated in only 5 rodents that exhibite
d low louse density, whereas low F-values (F < 5) were found at all louse d
ensities. Notwithstanding the tendency toward an inverse relationship betwe
en fecundity and infrapopulation density, the correlation was not significa
ntly different from 0.