THE EFFECTS OF APOSYMBIOSIS AND OF AN INFECTION WITH BLASTOCRITHIDIA-TRIATOMAE (TRYPANOSOMATIDAE) ON THE TRACHEAL SYSTEM OF THE REDUVIID BUGS RHODNIUS-PROLIXUS AND TRIATOMA-INFESTANS

We have investigated the effects of the absence of symbionts and of in fection with a trypanosome on the tracheal supply to different organs in larvae of the blood-sucking bugs, Rhodnius prolixus and Triatoma in festans. In bugs grown without symbionts there were extensive reductio ns in the tracheal supply to all the internal organs examined, These b ugs also excreted less fluid after blood meals, perhaps because of a r eduction in the oxygen supply to the Malpighian tubules, Inclusion of vitamin B in the diet of these affected insects reversed both the adve rse effects on diuresis and on the extent of the respiratory supply to the different internal organs. The results of these studies suggest t hat vitamin B may play a key role in the development and maintenance o f an adequate tracheal supply to the tissues in these insects. Infecti on with the trypanosome Blastocrithidia triatomae also greatly reduced the density of tracheoles supplying the rectum, small intestine and M alpighian tubules in infected T. infestans, but not in R. prolixus. It is possible, therefore, that the parasite exerts at least part of its pathogenic effect by causing a vitamin B deficiency, that in turn aff ects oxygen supply to the tissues. (C) 1998 Elsevier Science Ltd. All rights reserved.