Experimental life-cycle studies of Raillietiella gehyrae Bovien, 1927 and Raillietiella frenatus Ali, Riley and Self, 1981: pentastomid parasites of geckos utilizing insects as intermediate hosts

Abstract

SUMMARYThe life-cycles of two closely related cephalobaenid pentastomids, Raillietiella gehyrae and Raillietiella frenatus, which utilize geckos as definitive hosts and cockroaches as intermediate hosts, have been investigated in detail. Early development in the fat-body of cockroaches involves 2 moults to an infective, 3rd-stage larva which appears from 42–44 days post-infection. Complete development in geckos involves a further 5 moults in the case of males and 6 for females. Males mature precociously and copulation is a once-in-a-lifetime event which occurs around day 80 post-infection when both sexes are the same size but the uterus of the female is undeveloped. Sperm, stored in the spermathecae, is used to fertilize oocytes which slowly accumulate in the developing saccate uterus. Patency commences when the uterus carries approximately 4000–5500 eggs but only 25–36 % of these contain fully developed primary larvae. Since only mature eggs are deposited, we postulate that the vagina (?) of the female must be equipped with a selective filter that allows through large eggs but retains smaller, immature eggs. Thus the only limit on fecundity is the total number of sperms in the spermathecae and this is precisely the same factor that constrains egg production in the advanced order Porocephalida.

Pentastomids infecting an invader lizard, Hemidactylus mabouia (Gekkonidae) in northeastern Brazil

“…In Gekkonidae, particularly in house dweller species, their egg-contaminated faeces and prey items (such as cockroaches) usually result in very high prevalence and intensity of pentastomid infection (Ali and Riley, 1983;Riley et al, 1991). Thus, such trophic relationship of house geckos may explain in part the relative difference between the infection rates of H. mabouia and other sympatric lizards in northeast Brazil and very likely in other regions of this country.…”

“…It has been demonstrated experimentally that R. frenatus may utilize cockroaches as intermediate hosts (Ali and Riley, 1983;Jeffery et al, 1985;Bosch, 1986). The success in associating to new intermediate hosts might have been the keystone for R. frenatus to maintain itself in exotic hosts and would be favored due to widely distributed intermediate hosts like cockroaches (Criscione and Font, 2001).…”

Infection rates of pentastomids on lizards in urban habitats in the Brazilian northeast

“…There is also the possibility that the exotic pentastomid R. frenatus is specific for H. mabouia. Other investigations suggest that exotic geckos retained their natural pentastomid fauna (Self and Diaz, 1961;Ali et al, 1981;Ali and Riley, 1983;Pence and Selcer, 1988;Riley et al, 1988;1991). These exotic pentastomids appear to have been able to colonize intermediate hosts having wide geographic distributions, such as the cockroach, Periplaneta americana (Ali and Riley, 1983;Jeffery et al, 1985;Bosch, 1986;Criscione and Font, 2001).…”

Investigation of different ontogenetic stages of Raillietiella sp. (Pentastomida: Cephalobaenida): accessory genital glands

“…In cephalobaenid and porocephalid females, one precox copulation occurs (Sambon 1922;Hett 1924;Banaja et al 1975Banaja et al , 1977Riley 1983Riley , 1988Ali and Riley 1983;Haugerud 1989). The period during which copulation can occur in females lies between the complete development of the receptacula seminis and the beginning of uterus elongation, which removes the receptacula from the genital pore (Riley 1983;Bö ckeler 1984b).…”