INFESTATION DYNAMICS OF BLATTICOLA-BLATTAE GRAEFFE (NEMATODA, THELASTOMATIDAE), A PARASITE OF BLATTELLA-GERMANICA L (DICTYOPTERA, BLATTELLIDAE)

The life-cycle of the thelastomatid nematode Blatticola blattae Graeffe, a parasite of the cockroach Blattella germanica L., was experimentally studied. Male thelastomatids developed more rapidly than females. Analysis of the distribution of the nematode within a cockroach population revealed an important regulation of parasitic dynamics. The parasites were underdistributed in the samples of the host population. However, they were aggregated in first instar cockroach larvae. The sex ratio was unbalanced, in favour of males in younger cockroach larvae and in favour of females in older cockroaches. Analysis of the variations of this parasitism in relation to spatial structure of the population and host developmental stage revealed that infestation occurred mainly during the first three cockroach larval instars, and can originate from parasites in gravid female hosts. Finally, a strong regulation affects infrapopulations of the parasite, thus limiting males to one and females to one or two per host. These results can be compared with data on oxyurids parasitizing cockroaches of New Zealand.