William F. Fisher

Effects of Psoroptes ovis (Acarina: Psoroptidae) on certain biochemical constituents of cattle serum

Sera from Psoroptes ovis-infested calves were examined for 17 selected biochemical constituents to determine if P. ovis caused changes in any of these constituents. In order to recognize a scabies effect, there had to be a statistically significant (P less than or equal to 0.10) scabies exposure X time interaction and the changes in the biochemical constituents should have been correlated with the changes in the mite infestation. Five serum biochemical constituents fulfilled these criteria. Total protein, alpha-, beta-, and gamma-globulin were increased and total cholesterol was decreased at the peak of the scabies infestation. Precipitating antibodies to a P. ovis antigen were detected by immunodiffusion in some of the stored sera of the infested calves just after the peak of the infestation. Total protein, beta-, and gamma-globulin values were probably increased as a result of antibody production; alpha-globulin values were probably increased as a result of inflammation. As the scabies infestation declined, the mean values of all the above constituents from the infested calves, except cholesterol, began declining. Decreases in total cholesterol occurred, but they could not be entirely attributed to scabies. Examination of the serum biochemical constituents from a heavily infested calf that died during the test suggested that, in addition to antibody production and inflammation, kidney and liver damage may have occurred.

Natural transmission of Demodex Bovis stiles to dairy calves

Abstract Hides from cattle exposed to their infested dams for known periods and from sibling cattle were examined to determine when transmission of Demodex bovis occurred in an experimental dairy herd. Five of the 7 (71.4%) calves exposed to infested dams for 2 days, all 5 calves exposed for 3 days, and 1 calf exposed for 0.5 day became infested. Sibling cattle from 6 dams were examined; each had at least 1 calf that became infested. One dam produced twins, both of which became infested. These observations indicate that calves can acquire mites from an infested dam in 0.5 day and that sibling cattle from an infested dam do not always become infested.

Antigen-specific lymphocyte proliferative responses in vaccinated and Hypoderma lineatum-infested calves

Cattle infested with the common cattle grub, Hypoderma lineatum (Villers) develop specific humoral antibodies and a cellular immune reaction, defined by delayed-type hypersensitivity, to purified H. lineatum proteins. This investigation was designed to study the antigen-specific bovine lymphocyte response to hypodermin A (HyA), a serine protease of larval first-instar H. lineatum. Calves were vaccinated with either native or denatured HyA, and challenge-infested with H. lineatum. The kinetic development of a cellular immune response to HyA was monitored during vaccination and infestation. The HyA-specific responses were highly variable and weak during vaccination and infestation. Although HyA-specific lymphocyte blastogenic responses were observed, no correlation was noted between the magnitude of antigen-specific, peripheral lymphocyte proliferation and larval mortality. In striking contrast to responses observed during infestation, intense HyA-specific lymphocyte responses were observed with 3 calves 6 months after recovery from infestation. In addition, those responses were further heightened by a 250 micrograms booster injection of pure HyA.

Comparison of Lengths of Outer Opisthosomal Setae of Male Psoroptic Mites Collected from Various Hosts

Sweatman (1958, Can. J. Zool. 36: 905-929) reported that the location of Psoroptes mites on the host animal, i.e., ear or body, was one of the determining factors for separation of the psoroptic mites into species. He also confirmed the observation of Hirst (1922, Brit. Museum Nat. History, Econ. Ser. No. 13) that the setae on the opisthosomal lobes of the adult male were of diagnostic value. Sweatman concluded that the outer opisthosomal setae (OOS) or 14 setae (Fain, 1970, Rev. Zool. Bot. Afr. LXXXI: 95-100) was the primary factor in separation of the species and that Psoroptes ovis and P. bovis were the same species even though the host animals were different. Observations in our laboratory have indicated a wide overlap in the lengths of the 14 setae of adult males of psoroptic mites in our collections from various hosts and geographic locations. Sweatman also noted this overlap. The objective of our study was to compare lengths of the 14 setae of male psoroptic mites collected from various hosts from different geographic locations and to determine the reliability of the length of 14 setae as a characteristic to differentiate between species. Most of the mites studied were collected in recent years; however, additional mounted specimens were obtained from the collection of the Parasite Research Laboratory, Albuquerque, New Mexico, now located at Kerrville, Texas, as the Scabies and Mange Mite Research Unit of the U.S. Livestock Insects Laboratory. Mites collected from the ears of rabbits, goats, mule deer, white-tail deer, and ibex were considered to be P. cuniculi. Mites collected from the body of cattle and domestic sheep were considered to be P. ovis. Mites collected from bighorn sheep were considered to be P. ovis or P. cervinus. The mites were mounted on glass slides in Hoyers medium for measurements. Setal length was measured in micrometers (,um) with a Zeiss microscope equipped with differential interference-contrast, x 10 eye pieces, a x 40 objective, and a calibrated measuring reticule. Each 14 seta measured was considered an observation. Data were transformed to log 10 values and analyzed by one-way analysis of variance (ANOVA) for unequal sample sizes (Sokal and Rohlf, 1969, W. H. Freeman and Co., San Francisco, California, 776 p.). The differences between the means of the lengths of the 14 setae from the mites from various collections were analyzed by the Student-Neuman-Keuls (SNK) test for unequal sample sizes (Sokal and Rohlf, 1969, loc. cit.). The log 10 mean values were converted to their antilog value before being reported in the test. The lengths of the 14 setae of the adult male mites of Psoroptes spp. collected from the various hosts and geographic locations were compared statistically (Table I). The lengths of the 14 setae of mites (Mission strain) collected from sheep, of mites from bighorn sheep (Idaho), and of mites from cattle (Brazil) were all significantly different (P < 0.05) from the lengths of 14 setae from all other collections of mites regardless of host, body location, or geographic location. There were many differences within the same host animal. For example, the lengths of 14 setae from mites collected from rabbits from New Mexico, Kerrville, and England were all significantly different from each other. The lengths of 14 setae of mites collected from goats in Texas and New Mexico were significantly different from each other. The lengths of 14 setae of mites collected from cattle in the USA (Albuquerque, Kerrville, Hereford, and Colorado) were significantly different (P < 0.05) from those of mites collected from Holstein cattle from Brazil. The lengths of 14 setae from mites of the Mission strain from sheep were significantly different from those of all other strains of mites from sheep at Albuquerque, England, and South Africa. The lengths of 14 setae from mites of the mixed strain and the ADP strain were significantly different from those of the Beltsville-2 strain and England strain also. There was no consistency between the

Effects of citrate, heparin and cation supplementation on mortality and egg production of laboratory‐reared horn flies

Abstract. The effects of the blood anticoagulants sodium citrate and sodium heparin on horn fly, Haematobia irritans L., egg production were tested. Sodium citrate was added to freshly collected bovine blood to give final concentrations of 5‐100mM while sodium heparin was used in concentrations of 10–70 USP units/ml blood. Small cages containing five male and ten female newly emerged laboratory‐reared horn flies were maintained for 8–10 days on these blood samples, and mortality and egg production recorded daily. Results showed that as blood citrate concentration was increased, egg production decreased logarithmically. At sodium citrate concentrations of 50 mM and above, severe impacts on egg production and adult horn fly survival occurred. Although no dose‐related response of egg production to increasing heparin concentrations was noted, the 25 USP units heparin/ml blood treatments gave the largest egg production, yielding approximately 28% more eggs than any other treatment. Since citrate is a known chelator of divalent metal cations, the effects of supplemental cation additions to citrated blood were tested for their ability to reverse the egg production decrease seen at 50 mM sodium citrate. Blood samples containing 50mM sodium citrate were supplemented with CaCl2, calcium lactate, CuCl2, cupric acetate, FeCl3, ferric citrate, MgCl2, magnesium acetate, MnCl2, ZnSO4, EGTA or EGTA plus calcium lactate, each at 1 mM except EGTA which was used at 2.5 mM. The magnesium acetate supplement and the combination of calcium lactate plus EGTA resulted in a statistically significant increase in egg production (P< 0.05).