Studies of the Blood of Meloidae (Coleoptera) 1. the Haemocytes of Epicauta Cinerea (Forster), and a Synonymy of Haemocyte Terminologies1
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300 Cytologia 34 Studies of the Blood of Meloidae (Coleoptera) 1. The haemocytes of Epicauta cinerea (Forster), and a synonymy of haemocyte terminologies1 A. P. Gupta2 Department of Entomology and Economic Zoology Rutgers-The State University New Brunswick, New Jersey, U. S. A. Received July 22, 1968 Synopsis Haemocytes of the blister beetle, Epicauta cinerea, have been de scribed. Haemocyte terminologies in many classifications of insect haemocytes have been synonymized with a view to providing a summary of different haemocyte classifications for reference. Introduction Since Leydig's (1859) description of round and spindle-shaped cells and Magretti's (1881) and Cuenot's (1890) references to amoeboid cells in the blood of Meloe proscarabaeus L., haemocytes of several beetles have been described (Graber 1871, Lutz 1895, Hollande 1909, 1911, Barratt and Arnold 1910, Muttkowski 1924, Poisson and Patay 1939, Millara 1947, Arvy et al. 1948, Jones 1950, 1954, and McLaughlin and Allen 1965). However, none of these workers, with the exception of Hollande, has studied haemocytes of any meloid. Hollande (1911) included Lytta and Afeloe among the many Coleoptera that he studied. Beauregard (1890) has made only a passing reference to the blood cells in his extensive monograph on the blister beetles. Haemocytes of insects have been the subject of investigation for a fairly long time, and several attempts have been made to classify them. Such classifications are generally based either on the morphology and functions of the haemocytes or on their general staining and histochemical reactions. Thus, it is not unusual to find the same haemocyte or its various forms being referred to by different names, a situation which has inevitably resulted in a confusing mass of terminology. Since several physiological functions are attributed to certain haemocytes or their variant forms, it is necessary that insect haematologists follow a uniform terminology and classification in order to avoid any confusion in the interpretation and understanding of works of different authors. According to Millara (1947), Cuenot (1896) first classified haemocytes 1 Paper of the Journal Series , Agricultural Experiment Station, Rutgers-The State University New Brunswick, New Jersey. 2 Associate Professor . 1969 Studies on the Blood of Meloidae (Coleoptera) I 301 into four categories, and was later followed in this attempt by Hollande (1909 , 1911) and others. Wigglesworth (1939) summarized most of the earlier classifications, and prepared a classification which has been widely accepted . More recently, Jones (1962) revised Wigglesworth's classification with a few modifications. Jones' classification has been adopted in the present work with one exception, that is the category of prohaemocytes has not been recognized . It has been stated elsewhere (Gupta and Sutherland 1966) that prohaemocytes are earlier or young stages of plasmatocytes. The objectives of this paper are 1) to describe briefly and illustrate the haemocytes of E. cinerea , and 2) to atttempt to restore some order in haemocyte classification by synony mizing various terminologies, with a view to providing a summary of different classifications for reference. Materials and methods Observations were made on fixed and unfixed haemolymph, samples of which were always taken from the antennae of adult beetles of both sexes collected from wild golden-rod (Solidago sp.) plants. Examination of haemo cytes was done in hanging drops of physiological saline (NaCl, 0.9g; KCl, 0.042g; CaCl2, 0.082g; NaHCO3; 0.002g; distilled H2O, 100ml) with 2 versene. All observations were made at room temperature (28•‹-30•Ž); All photomicrographs were taken by a dark phase contrast Leitz microscope at a magnification of 400. Observations (Figs. 1-7, 9, 11, 13, 14) Examinations of haemolymph from Epicauta, revealed the presence of plasmatocytes, granular haemocytes, spherule cells, oenocytoids, and cysto cytes. Adipohaemocytes, podocytes and vermiform cells were not observed. Plasmatocytes were predominant and were observed as round, fusiform, and lamellate cells. The cytoplasm in some of them appeared granular and the nuclei were usually centrally located. Occasionally binucleate plasmatocytes were also observed. Granular haemocytes were comparatively very rare. The nucleus in these cells was usually indistinct, due to the presence of cytoplasmic granules. Both round and fusiforms granular cells were observed. Spherule cells were found to be more numerous than the granular cells and were present either as round or fusiform cells. The spherules in the cytoplasm varied in number from two to several in various cells. Their size was also variable, sometimes the same cell showing spherules of different sizes. The nucleus in most spherule cells is usually concealed by the spherules. Mature spherule cells were observed in the process of releasing their spherules into the haemolymph. Oenocytoids, like the granular haemocytes, were compara tively very rare. They were usually fusiform in shape, although spherical forms were sometimes observed. The nucleus was generally eccentric. The 302 A. P. Gupta Cytologia 34 fi ne cytoplasmic canaliculi and granular strands, considered characteristic of oenocytoids in Galleria and other insects, were not observed. The cystocytes are usually hyaline cells with characteristic cartwheel-like nuclei. They are usually fewer in number than other haemocytes, although several of them are Figs. 1-7. 1 and 2, plasmatocyte (Epicauta cinerea). 3 and 4, granular haemocyte (E . cinerea). 5 and 6, spherule cell (E. cinerea). 7, oenocytoid (E. cinerea). 1969 Studies on the Blood of Meloidae (Coleoptera) I 303 observed in a coagulated sample of haemolymph. In addition to the above inentioned haemocytes, clusters of spherules were also observed in the haemo lymph. In several samples of unfixed haemolymph, coagulation spots were formed, and these provided material for study of coagulation patterns and Figs. 8-11. 8, podocyte (Periplaneta americana nymph). 9, cystocyte (E. cinerea). 10, adipohaemocyte (Galleria mellonella). 11, cluster of spherules; notice that the spherules look nucleated (E. cinerea). 304 A. P. Gupta Cytologia 34 Figs. 12-14. 12, vermiform cell (P. americana). 13 and 14, coagulation patterns (E. cinerea). 1969 Studies on the Blood of Meloidae (Coleoptera) I 305 the role of haemocytes, if any, in the process of coagulation . Examination of several coagulation spots showed only cystocytes . Whether cystocytes actually cause coagulation or are the result of coagulation is difficult to say . It should be noted here that in samples in which a differential count would show very few cystocytes, induced coagulation would reveal several of these cells. Probably during such induced coagulation, certain fragile plasmatocytes are unable to withstand the mechanical stress-and perhaps some physiological stress in vivo-and suddenly release their cytoplasmic contents, which form the peculiar cytoplasmic strands, so characteristic of the coagulation pattern . These granular cytoplasmic strands ramify randomly and enclose several cystocytes. No granular islands around the cystocytes were observed, although cytoplasmic veils enveloping all of the cytoplasmic strands, and the cystocytes were visible. Occasionally, coagulation spots without cytoplasmic strands were also observed. Synonymy of haemocyte terminologies The terminologies synonymized in Table 1 are variously based on stained or unstained fresh or fixed haemolymph. Some are based on histochemical studies on the haemocytes. Some descriptions included haemocytes of only immature stages, some of adults, and some of both stages. Homologies have been established on the basis of description, line drawings, and photomicro graphs of original authors. Cells which could not be homologized have been included in the category of "others." In some cases cells included in this category may not necessarily be haemocytes. Generous use of footnotes has been made to include pertinent information on the original classifications. Except in a few cases, only Anglicized versions of original terms have been included in the table. Terms in parenthesis were not used by the original authors, but were adopted by the present writer after scrutinizing original descriptions and figures, and represent only approximations to the category they have been assigned to in the table. The identity of term "with?" is uncertain. Haemocytes categorized as phagocytes and amoebocytes by previous authors have been assigned to the category of plasmatocytes, although they could also be included with granular haemocytes, spherule cells, and adipo haemocytes, inasmuch as these latter three forms are also phagocytic in nature. No attempt has been made to include the current generic and specific names of the species by many of the earlier authors. Where no specific name of the insect was given by the original author only common familial or ordinal names have been included. Ordinal designations in the table have been included for all the species, whether these taxonomic designations were given by the original authors or not. The name of the author of every species has been omitted. Taxonomic designations were checked from Cresson (1887), Kirby (1892), Heyden et al. (1906), Blatchley (1920), Leng (1920), Brues et al. (1954), Harz (1957), Borror and Delong (1960), and Imms (1960). All Table 1. (Continued) Table 1. (continued) 1 Graber 1871. Although he has attempted to arrange the species he studied under four categories,