Andrew J. Main

EFFECT OF SEX, SIZE, AND AGE OF COMMENSAL RAT HOSTS ON THE INFESTATION PARAMETERS OF THEIR ECTOPARASITES IN A RURAL AREA OF EGYPT

The present study was carried out in the Bilbeis area, Sharqiya Governorate, Egypt. A total of 127 male and 115 female black rats Rattus rattus and 124 male and 153 female Norway rats R. norvegicus was collected during the study period. A total of 20,643 and 40,997 ectoparasites was recovered from R. rattus and R. norvegicus, respectively. Three common mite species were recovered from both rat hosts: Ornithonyssus bacoti, Radfordia ensifera, and Laelaps nuttalli. Three common flea species were also recovered from both rat hosts: Echidnophaga gallinacea, Leptopsylla segnis, and Xenopsylla cheopis. Polyplax spinulosa was the only louse species that infested both rat hosts. Rats that lived more than 12 mo formed about 24 and 14% of the populations of the black and Norway rats, respectively. The prevalences and general indices of many ectoparasites were significantly higher on males than on females of both rat hosts. Seasonal differences in prevalences and general indices of many ectoparasites were recorded between the 2 sexes of both rat species. Prevalences and general indices of most ectoparasites on both rat species showed a tendency to increase with increasing size and age of rat hosts. The type and degree of correlation between prevalences and general indices on the one hand and each of body size and age on the other hand differed among the species of ectoparasites.

Viruses in Ixodes Uriae (Acari: Ixodidae) from Seabird Colonies at RøSt Islands, Lofoten, Norway

Abstract A total of 1929 Ixodes uriae collected from Røst Islands, Lofoten, Norway, in July 1974, was divided into 204 pools and inoculated into suckling mice and chick embryo cell cultures for virus isolation. Virus was detected in 6.6% of the laboratory-molted female ticks, 5.4% of the males and 1.8% of the nymphs. No isolates were obtained from 149 unengorged adult ticks. Of 50 viral strains recovered, 30 belonged to the Uukuniemi group, 13 to the Kemerovo group, and I was a strain of Tyuleniy of Group B. Of 6 untyped strains, I was orbiviruslike and I resembled a coronavirus in a negative-staining electron microscopy. The infection rates of I. uria in Lofoten were similar to those reported in the Murmansk area in the northern USSR.

Nucleic Acid Levels in the Developing Ovaries of Hyalomma (Hyalomma) dromedarii (Acari: Ixodidae)

Protein and nucleic acid levels from the ovaries of Hyalomma dromedarii Koch were determined during different stages of oogenesis. The concentrations of total protein, DNA, and RNA increased during oogenesis, reflecting the rapid developmental changes taking place in this tissue. Peak protein and DNA levels were reached in the fully fed females, whereas RNA level peaked slightly earlier. Ribosomal RNA (rRNA) was found to be composed of 27.0s, 17.0s, and 4.1s particles. The ratio of 27.0s to 17.0s varied within the developing ovary, yet the 27.0s/4.1s ratio remained constant. The nucleotides of total RNA and rRNA were determined, and the ratio of purine/pyrimidine equaled approximately 1 and remained unchanged during oogenesis.

Vaginal Eversion in a Bat Tick, Argas (Chiropterargas) boueti Roubaud and Colas-Belcour (Acari: Argasidae)

Vaginal eversion was observed in Argas (Chiropteragas) boueti. During eversion, both cervical and vestibular parts of the vagina are fully everted so that the former is anteriorly oriented, whereas the latter occupies the posterior end of the everted organ. The histology of normal and everted vaginas is described and correlated with its functional and biological significance. Vaginal eversion most likely occurs while the tick is ovipositing and may be involved in the wax-coating process of eggs by Genes organ.

Egg Ribosomes of Argas (Persicargas) arboreus (Acari: Argasidae)

The ribosomes from Argas (Persicargas) arboreus Kaiser, Hoogstraal, and Kohls eggs were isolated, and their ability to initiate protein synthesis in a cell-free system was investigated. A greater proportion of polymeric forms was detected in the ribosome fractions at late embryogenesis than at early embryogenesis. Synthesis of RNA, ribosomal RNA, and ribosomal protein occurred during embryogenesis. The ratio of rRNA/rprotein was 1:1.02–1.15, of purines/pyrimidines was 1:1.06–1.10, and of 6-keto groups/6-amino groups was 1:1. Twenty-one different ribosomal proteins were separated by disk electrophoresis. The requirements for an amino acid-incorporating system from A. arboreus eggs were established. The pH 5 enzymes prepared from the tick eggs successfully supported the incorporation of C14 leucine by isolated ribosomes from A. arboreus eggs. RNase, but not DNase, inhibited the protein activity. The functioning of the A. arboreus ribosomes requires Mg++, GTP, ATP, or all of these.

Biochemical Effects of Juvenile Hormone III on the Tick, Argas (Persicargas) arboreus (Acari: Argasidae), During Embryogenesis

The biochemical effects of juvenile hormone III (JH III) on developing embryos from treated female Argas (Persicargas) arboreus Kaiser, Hoogstraal and Kohls were examined. Exogenous JH III resulted in a decrease in total proteins (P less than 0.001) only during the first 2 d of embryogenesis. There was no significant difference (P greater than 0.05) between RNA and DNA content in eggs from control and JH III-treated females. No significant difference (P greater than 0.05) was observed between control and JH III eggs in their lipid or phospholipid contents throughout embryogenesis. A total of 14-17 protein bands and 6-8 glycoprotein bands were separated by electrophoresis during embryogenesis of A. arboreus with some differences in mobility ratio between bands from control and JH III eggs. Differences in activity and isozyme patterns of malic acid, lactic acid, glucose 6-phosphate dehydrogenase, acid phosphatase, and alkaline phosphatase were not observed during embryogenesis of control and JH III-treated A. arboreus. Differences were observed in esterase activity.