92 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I4I 



Symbiosis is the living together in more or less intimate associa- 

 tion of organisms of different species ; it includes virtually all rela- 

 tionships between cockroaches and other organisms, such as parasit- 

 ism, predatism, commensalism, and mutuahsm. Alice et al. (1949) 

 apparently do not include predatism in symbiosis. 



Mutualism is symbiosis in which both members benefit by the 

 association. The smaller partner has commonly been called a sym- 

 biont or symbiote by authors. 



Commensalism includes associations in which neither party ap- 

 pears to benefit or be harmed. One partner may live on the surplus 

 food or wastes of the other ; shelter and transport may be involved. 



Parasitism is the state of symbiosis in which one of the members 

 feeds upon the other during the whole of either the immature or 

 mature feeding stage; the host is harmed in some way and may be 

 killed. 



Predatism is an association in which one member attacks and feeds 

 upon, or stores as food for its progeny, one or more other organisms ; 

 the predator spends less than the immature or mature feeding period 

 on the prey. This category includes a few invertebrates and all the 

 vertebrates that capture, kill, and feed on cockroaches. This associa- 

 tion may be divided into interspecies predatism, in which the preda- 

 tor preys upon a different species, and intraspecies predatism (canni- 

 balism) in which the predator preys upon its own species. 



Although we have attempted to adhere to these definitions through- 

 out this discussion, we realize that in doing so we may have tended to 

 oversimplify complex relations. Some questionable interpretations 

 stem from insufficient knowledge of the basic relationships between 

 cockroaches and their associates. Only further study will clarify these 

 relationships. Some of the problems are discussed below. 



Probably many of the so-called parasites (e.g.. Protozoa like 

 Nyctotherus, and intestinal nematodes of the family Thelastomati- 

 dae), which do not invade the host's tissues and seem to have no effect 

 on the activity and vitality of the host, are commensals. Although we 

 consider these forms to be commensals, we realize that they might 

 actually affect the host in some way even though this has not been 

 shown. It is possible that Rothschild and Clay's (1957) statement 

 about bird parasites may well apply to the apparently harmless organ- 

 isms found in the cockroach. These authors wrote, "It cannot be too 

 strongly emphasized that the effect of all types of parasites on the 

 host is detrimental. If we find that a bird seems little, if at all, in- 

 convenienced by the presence of Protozoa or worms or lice, or a 

 cuckoo in the nest, we can nevertheless assume that it would be better 



