Effects of Potato Beetle Hemolymph Injections on Physiological Responses in the Albino Rat

The hemolymph of both the potato beetle, Leptinotarsa decemlineata, and the false potato beetle, Leptinotarsa juncta, injected intraperitoneally into white rats produced deviant physiological responses. Monitoring showed a decrease in injected rats' temperatures. Injected rats showed an increase in serum glucose and serum urea. An increase in the serum-enzyme activity of serum glutamic pyruvic transaminace, serum glutamic oxalacetic transaminase, and lactic dehydrogenase also occurred. Fluctuations in serum ions showed a decrease in sodium concentration, but an increase in levels of potassium, calcium, and phosphorus. Beetle-hemolymph injections appeared to cause a change in the rats' hemic tissue intergrity. Perturbation of the hemic integrity resulted in a state of shock which resembled anaphylactic shock. INTRODUCTION Recently it has been demonstrated that the hemolymph of the Colorado "true" potato beetle, Leptinotarsa decemlineata, is toxic to mice (Hsiao and Fraenkel, 1969). Gross observations indicated that beetle hemolymph also had a generalized toxic effect on rats. It was of interest therefore to examine further the toxic effects of potato-beetle hemolymph on some of the rat's physiological responses. Holtzman white rats, rather than mice, were used in order to obtain sufficient blood with which measurements could be made. The physiological parameters monitored on the rats were body temperature, respiratory rate, heart rate, hematocrit, blood urea, serum gluose, serum transaminase, lactic acid enzyme activity, and serum electrolyte levels. The hemolymph of the false potato beetle, Leptinotarsa juncta, was likewise investigated, because this beetle also utilizes a toxic plant for its food source. The acute toxicity of the hemolymphs of these two beetles and their effects on rats' physiological responses are described here. MATERIALS AND METHODS Field-collected true potato beetles, Leptinotarsa decemlineata, and field-collected false potato beetles, Leptinotarsa juncta, were used to establish cultures in the laboratory. Cultures of the true potato beetle were maintained in the laboratory on potato leaves. Cultures of the false potato beetle were reared on leaves of horsenettle, Solanum carolinense. Possible toxic effects of hemolymph from both kinds of beetles were tested by intraperitoneal injection into Holtzman white rats. Rats were used in groups of 10—10 experimental and 10 control animals—in most experiments. Each sample contained 50/ul of hemolymph taken from true adults, true fourth-instar larvae, false adults, and false fourth-instar larvae. Control hemolymph was obtained from field-collected grasshoppers of the genus Melanopus, taken from the same Manuscript received December 13, 1972. THE OHIO JOURNAL OF SCIENCE 74(3): 145, May, 1974 146 RAYMOND M. GESINSKI, ET AL. Vol. 74 area as the beetles. These grasshoppers were used as controls because of their fairly large size, which facilitated obtaining hemolymph from them. Body temperature, respiratory rate, and heart rate of rats were monitored with a Physiograph Six, using a Small Animal Study Unit (Narco Bio-Systems, Inc., Houston, Texas). Microhematocrit determinations were made using heparinized capillary tubes. Urea was determined from Somogyi nitrate of hemolyzed blood samples by the colorimetric technique of Archibald (1945). Serum glucose was measured by an enzymatic colorimetric procedure using the enzymes glucose oxidase and peroxidase according to the method of Raabo and Terkildsen (1960). Determinations of glutamic oxalacetic transaminase (SGO-T) and glutamic pyruvic transaminase (SGP-T) were made according to the colorimetric methods of Reitman and Frankel (1957). Serum lactic dehydrogenase (LDH) was determined according to Cabaud and Wroblewski (1958). All enzyme activities are listed in international units. Determinations of sodium and potassium were made by flame-photometric procedures of Holiday and Preedy (1953). Calcium was determined by the procedures of Bett and Fraser (1959). Inorganic phosphorus was quantitated by the colorimetric procedure of Taussky and Shore (1953).