A neuroendocrine relationship between the nematodeHammerschmidtiella diesingiand its insect host,Blatta orientalis

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Abstract
Various endocrine operations were performed on the adult female cockroachBlatta orientalisand the adult populations of the nematodeHammerschmidtiella diesingiwere recorded 2 or 4 weeks later. Cautery of the median neurosecretory cells (m.n.c.) caused a significant reduction in total numbers of adult nematodes after 2 or 4 weeks; after 2 weeks, removal of the retrocerebral complex (corpora cardiaca plus corpora allata) caused a significant overall reduction in the adult nematode burden and this could not be prevented by reimplanting the corpora allata immediately after the retrocerebral complex had been removed.Anomalies appeared in the data when the sex of the parasite was examined and this may be related to a possible postembryonic mode of sex determination.Bothm.n.c. cautery and removal of the retrocerebral complex suppressed host terminal oocyte development and ootheca production, whilst reimplantation of corpora allata into ‘retrocerebralectomized’ cockroaches allowed reproductive processes to continue normally. Hence, them.n.c. and corpora allata are essential for host egg development.Histological studies showed a profound reduction in fuchsinophilic material in the corpora cardiaca ofm.n.c. cauterized cockroaches.Although them.n.c. may affect the nematode directly or indirectly, a direct effect on the parasite by the corpora allata is unlikely.