Observations on the symbiotes of certain Coccidae

Abstract

does not appear. First page follows. Introduction In the course of his studies on the anatomy of Coccus hesperidum Linn., Leydig (1854)3 observed small lanceolate-shaped bodies in the hemolymph of this insect. More than thirty years later their organismal nature was definitely recognized (Moniez, 1887); (Lindner, 1895); (Šulc, 1906), and they became known as yeastlike symbiotes probably playing a beneficial role in the life of their host. They have been found to be present in all species of Coccidae examined, and in every individual of the species, being transmitted from one generation to the next through the egg. Of interest is the fact that the Diaspididae, or armored scales, do not harbor these yeastlike microorganisms in their hemolymph, although other types of symbiotes may be found in other locations in these insects. Although certain coccids have been reported to be susceptible to certain microbial pathogens, especially certain fungi, the use of microorganisms as control agents against these insects has, so far, not proved to be generally practical. In view of this state of affairs, the writer has for some time toyed with the idea that possibly the relationship between the symbiote and the host insect could be altered so as to be detrimental to the insect and perhaps to cause its death. Theoretically this might be accomplished in one of two ways: (1) Circumstances might be created that would destroy the symbiote even though they would not directly affect the insect. If, as is known to be true with some insects, the life of the host insect is dependent upon the symbiote, destruction of the latter would mean the death of the insect. This is known to occur in certain other insect species. (2) The environment of the insect might be altered in a manner that would cause the symbiote to become pathogenic for its host (a possibility suggested by (R. H. Smith, 1944) or to multiply to a degree that would cause the death of its host. It is conceivable that if the yeastlike symbiotes were to increase greatly in size or number the moisture content of the insect would greatly decrease, the nutritional balance of the insect tissues would be altered, and waste products or metabolites from the rapidly developing symbiote would accumulate. Such changes would certainly be to the detriment of the host insect.