The responses of scapularis (Acari: Ixodidae) nymphs and adults to extracts of cast larval skins were tested in a Petri dish bioassay. Assembly was elicited in nymphs and adults in the presence of skins, exudate from ticks, and filter paper exposed to ticks compared to untreated controls. Assembly was noted by 1 hr after exposure with little change between 1 and 24 hr. The assembly response increased in the presence of an increased number of skins. Similar assembly was elicited in nymphs and adults in the presence of cast larval skins and a saline (0.95% NaCl) skin extract. Methanol and hexane extracts were not attractive. When chemical standards were tested against nymphs, they responded to guanine, uric acid, hypoxanthine, xanthine, inosine, and hematin. Adults were tested against guanine, inosine, and xanthine, and all elicited significant assembly. Responses of nymphs increased significantly with increase in dose of uric acid and guanine. Responses of nymphs to a mixture of guanine, xanthine, and adenine (25:1:1 ratio) were similar to responses to cast skins. This study provides the first evidence of an assembly pheromone in I. scapularis.

Ten known or potential components of the aggregation-attachment pheromone (AAP) of the ticks Amblyomma hebraeum and A. variegatum, as well as mixtures of these components, extracts of prefed males and live prefed males, were tested as aggregation stimulants. In field assays, laboratory-reared unfed male and female ticks were released 20 cm downwind Of CO2/pheromone release sites; the numbers of ticks that aggregated at the release sites were recorded after 30 min. In A. variegatum, aggregation was induced by methyl salicylate, o-nitrophenol, 2,6-dichlorophenol, phenylacetaldehyde and some mixtures containing these compounds; a strong aggregation response was induced by an extract of five prefed males A. variegatum and a weak response was induced by an extract of 50 prefed males of A. hebraeum. In A. hebraeum, aggregation was induced by phenylacetaldehyde. mixtures of compounds that included phenylacetaldehyde, extracts of 50 prefed males of A. hebraeum or A. variegatum and 50 live prefed males of.A. hebraeum. In A. variegatum, aggregation was inhibited if compounds that do not occur naturally in the AAP of the species were included in mixtures. In A. hebraeum, phenylacetaldehyde appeared to act as an arrestant for ticks that had been attracted to release sites by other compounds.

Changes in DNA, RNA, total lipids, phospholipids, and proteins and the activity of certain enzymes and pattern of their isozymes were studied in Hyalomma dromedarii Koch during embryogenesis. Total proteins fluctuated with a net increase (P less than 0.05) on day 20. Total lipids increased during the first half of embryogenesis and then declined with a net decrease to about 60% of the original level. Total phospholipids decreased to half this original level. DNA content increased greatly during cleavage, gastrulation, and organogeny and RNA increased during cleavage and blastula formation. Glucose-6-phosphate dehydrogenase (G6PDH) activity decreased (P less than 0.05), reaching 20% of its original level on day 12. Malic acid dehydrogenase (MDH) activity remained nearly unchanged throughout embryogenesis. Lactic acid dehydrogenase (LDH) activity increased greatly, with the highest level on day 14 with no further change. Acetylcholinesterase (AchE) activity increased greatly during the first 12 d, with no significant change thereafter. Acid (ACP) and alkaline (ALP) phosphatase activity increased during the first 12 d and declined returning to the original level on day 20. Seven AchE and 5 LDH isozymes were detected during different embryogenesis stages. Two MDH, 2 ACP, 1 ALP, and 2 G6PDH isozymes were detected throughout embryogenesis. Treating the mother with 20-hydroxyecdysone was associated with increases in protein and RNA contents and G6PDH and AchE activity and with decreases in ACP and ALP activity in the embryos.

Juvenile hormone (JH)-I and -III were used as model substrates to study the in vitro metabolism of JH in the hemolymph and body homogenates of the American dog tick, Dermacentor variabilis (Say). Ester hydrolysis was the principal pathway of JH metabolism in hemolymph and homogenates. JH also was converted into JH-diol primarily by body homogenates, indicating the presence of JH epoxide hydrolase activity. JH epoxide hydrolase activity, alpha-naphthyl acetate esterase activity, and protein concentration per milligram wet weight were significantly lower (t test, alpha = 0.05) in homogenates of partially fed, virgin and replete, mated females of D. variabilis compared with unfed, virgin females. The decline in these factors was probably because of the influx of water into the tissues caused by the blood meal. In addition, the epoxide hydrolase and alpha-naphthyl acetate esterase activity per milligram tissue protein decreased significantly during this time. Mating of fed females rather than feeding alone caused a significant decline in the tissue JH esterase activity per milligram wet weight but not per milligram protein. The JH esterase activity per milligram protein was significantly higher in partially fed, virgin and replete, mated females compared with unfed females, indicating that feeding may actually increase JH esterase activity on a protein basis. JH-III was metabolized 1.4 times faster than JH-I by the hemolymph of partially fed, virgin females. The inhibitors O,O-diisopropyl phosphorofluoridate and octylthio-1,1,1-trifluoropropan-2-one at 10(-4) M inhibited JH and alpha-naphthyl acetate esterase activity in hemolymph and body homogenate.

The moulting sex pheromone of Dermacentor variabilis, the American dog tick, is cholesteryl oleate. This steryl ester, when present in amounts from about 1 to 0.1 female equivalents elicited male mounting responses that were indistinguishable from the natural controls. Other steryl esters present on the tick's body surface also elicited responses, but a significantly lower intensity than cholesteryl oleate. Long regarded as a waste product of vertebrate blood feeding, this material is secreted by sexually mature females during feeding and accumulates on the surface of the body cuticle. Mate-seeking males, attracted to the females by the presence of 2,6-dichlorophenol, recognize and mount the feeding females. The accumulation of cholesteryl oleate on the female's body surface during blood feeding is an indication of successful parasitism and acts as a signal of female mating readiness. Compounds of unknown composition that co-chromatographed with steryl esters were also found in fed females of 4 other ixodid tick species. Bioassays performed with crude extracts of these different species suggest that mounting sex pheromones are widespread in the Ixodidae and may also use the same or similar steryl esters, either alone or in mixtures, as in D. variabilis.

Chemical analysis and male bioassay responses were used to investigate possible components of the genital sex pheromone of D. variabilis and D. andersoni. Bioassays with D. variabilis indicated greatest responses to myristic, palmitic, stearic, arachidic, and behenic fatty acids as well as myristic and stearic methyl esters. Responses of D. variabilis decreased with changes in chain length, different functional groups and unsaturation. Bioassays with D. andersoni indicated greatest responses to palmitic acid as well as moderate responses to other fatty acids and methyl esters. Chemical analysis revealed the presence of myristic, palmitic, palmitoleic, stearic, oleic and linoleic acids and several unknown compounds in the vaginal lumen and on the external gonopore area. Total free fatty acids in vaginal extracts were 24.8 ng/female equivalent in D. variabilis and 297.2 ng/female equivalent in D. andersoni. Saturated free fatty acids ranging in chain length from C14 to C22 appear to serve as components of the genital sex pheromone of D. variabilis and D. andersoni. Most of these components are present in the lumen of the vestibular vagina and on the external gonopore surface.

Feeding and engorged nymphs and unfed and feeding adult Hyalomma dromedarii were treated topically with 5, 20, and 50 μg of 2 insect growth regulators (IGRs): IGR-A, 3-[7-(2,6-dichlorophenoxy)-3-methyl-4-heptenyl]-2,2-dimethyloxirane, and IGR-B, 5-[(6,10-dimethyl-4,9-undecadienyl) oxy]- 1,3-benzodioxole. IGR-B was more toxic than IGR-A. Nymphs tolerated both IGRs, but emerging adults exhibited an increasing delayed mortality with dosage increase without attempting to feed; males exhibited higher mortality than females. Ticks treated in the adult stage tolerated all doses of both IGRs. Neither IGR altered the nymphal premolting period or the adult sexual behavior, but both caused a small reduction in fertility (egg hatch) of both sexes. The results suggest that these IGRs do not mimic or antagonize naturally occurring juvenoid(s) in H. dromedarii and/or that the administration method is unsuitable.

Camel ticks, Hyalomma dromedarii, utilized inoculated 14C cholesterol to synthesize apolar ecdysteroids, unknown polar ecdysteroids, and fractions coeluting with ecdysone and 20-hydroxyecdysone (20-OH ecdysone). Following inoculation into feeding virgin females, most 3H ecdysone was metabolized to nonimmunoreactive apolar compounds; lesser amounts were metabolized to 20-OH ecdysone, 20,26-dihydroxyecdysone, and possibly other unidentified ecdysteroids. Identification of these compounds was supported by coelution with authentic reference standards, coelution of radioactivity, radioimmunoassay, nuclear magnetic resonance, and infrared spectrometry of the purified fractions. Assay of the apolar ecdysteroids in extracts from ticks inoculated with 14C acetate demonstrated conjugation with carbon-containing compounds. Hydrolysis of the highly apolar ecdysteroids released 20-OH ecdysone, ecdysone, and 20,26-dihydroxyecdysone. Methylation of the hydrolysis products revealed long-chain fatty acids, especially palmitic, stearic, oleic, and linoleic acids, all confirmed by gas chromatography/mass spectrometry. The possible sites of metabolism of ecdysteroids in these ticks was investigated. Most of the ecdysteroid metabolites produced were found in the midgut (60.4%) and in the combined epidermis and fat-body tissues (31.1%). Small amounts of ecdysteroids were found in the previtellogenic ovaries of these virgin female ticks (1.5%). Ecdysone and 20-OH ecdysone were found in the hemolymph, but no apolar ecdysteroids were found in the circulatory fluids.

The “baited pesticide treatment station” technique for reducing natural populations of the American dog tick, Dermacentor variabilis, is described. In laboratory and field trials, small mammals attracted to a baited container coated themselves with dust or oil containing small quantities of pesticide, resulting in highly significant reductions in the numbers of immature ticks on animals in the treated area as compared to animals in the control area. Immature ticks on small mammals in the experimental area were reduced by 81.2% compared to small mammals in the control area in one of the field trials, and by 97.8% in another field trial; no immatures were found on animals in the experimental area in a 3rd field trial. The potential usefulness of this technique for area control of American dog ticks, particularly in areas of high human population densities, is discussed.

In contrast to the exceptional diversity of semiochemical-regulated behavior in the insects, chemical communication in the Acari is restricted to a few limited roles. These include clustering, mate-finding processes, host- and food-finding processes, and dispersal. No evidence of pheromones regulating oviposition, necrophoric behavior, recognition of hive mates, or many other processes found in numerous insect groups has been reported in the Acari. Perhaps the most noteworthy feature of acarine pheromones or allomones is the use of the same or similar molecules by many species. Metastriate ixodids use volatile phenols to regulate courtship behavior and, in at least one species, feeding site selection and attachment as well. Argasid ticks use a water- or saline-soluble assembly pheromone, which appears to represent a single type of compound, if not the identical compound in all cases. Acarid mites use terpenoids as alarm pheromones and allomones, while certain phytoseiid and tetranychnid mites use terpene alcohols as arrestant sex pheromones. Another notable feature of acarine pheromones is the use of multicomponent signals to regulate different events in the behavioral process. Thus, two separate sex pheromones are necessary to successfully complete courtship in certain Dermacentor ticks, while three pheromones appear necessary to complete feeding-site selection, attachment, and clasping in certain Amblyomma species. In other cases, a combination of chemical and physiological signals is used to regulate courtship. Although the same or similar compounds may be used for chemical communication, no universal model describes the behavior of all species in an acarine family or order. Species-specific differences in perception of pheromone concentration, molecular composition, aphrodisiacs, and other selective signals facilitate species isolation, even though the initial steps in the behavior are similar in all species. This combination of unity and diversity allows economy in the biosynthesis of semiochemicals without compromising species integrity. In the brief period following the pioneering discoveries of pheromones in ticks (8) and mites (16, 17), evidence of a variety of acarine semiochemicals has been obtained, several pheromones and allomones have been identified, a sex pheromone gland has been described, and considerable effort has been directed to understanding the regulation of pheromone activity. Nevertheless, our knowledge of communication in this large and exceptionally diverse group is meager.(ABSTRACT TRUNCATED AT 400 WORDS)

Feeding and engorged nymphs and unfed and feeding adults of Hyalomma (H.) dromedarii were treated topically with 10, 20, and 50 μg juvenile hormone I (JH I). Large doses of JH I were lethal to adults; nymphs tolerated JH I, but emerging adults exhibited delayed mortality, which occurred after attachment to the host. The premolting period was prolonged by 9.4 to 31.0% in nymphs treated on repletion day but not in those treated at other times. JH I did not alter adult sexual behavior and caused only a small reduction in fertility of both sexes. The results suggest that H. dromedarii systems did not respond toJH I because it may be very different from tick JH and/or the administration method was unsuitable.

Topically applied β-ecdysone is lethal to feeding and engorged nymphs and to unfed and feeding adults of Hyalomma dromedarii in 10- and 20-μg doses. Premolting mortality was higher in nymphs treated while feeding than in those treated postengorgement. The 10- and 20-μg doses caused accelerated molting in all nymphal groups; the 1- and 5-μg doses also produced this effect in nymphs treated while feeding. No alteration in adult sexual behavior was observed. Twenty micrograms applied during adult feeding caused a drastic reduction in fertility of both sexes. Reductions in male fertility were also noted when nymphs were treated 10 days postengorgement with 1-, 5-, 10-, and 20-μg doses.

Journal Article Precocene-2 Effects on the Camel Tick, Hyalomma Dromedarii (Acari: Ixodidae): 1. Adult responses Get access Souraya H.A. Gaber, Souraya H.A. Gaber 3Zoology Department, Faculty of Sciences, Al-Azhar University for Girls, Cairo, Arab Republic of Egypt. (Guest Investigator, Medical Zoology Department, NAMRU-3.) Search for other works by this author on: Oxford Academic PubMed Google Scholar Galila M. Khalil, Galila M. Khalil 5Medical Zoology Department, United States Naval Medical Research Unit Number Three (NAMRU-3), American Embassy, Cairo Search for other works by this author on: Oxford Academic PubMed Google Scholar Daniel E. Sonenshine, Daniel E. Sonenshine 6Department of Biological Sciences, Old Dominion University, Norfolk, Virginia 23508, USA. Search for other works by this author on: Oxford Academic PubMed Google Scholar Mohamed K. Abdel Moez Mohamed K. Abdel Moez 3Zoology Department, Faculty of Sciences, Al-Azhar University for Girls, Cairo, Arab Republic of Egypt. (Guest Investigator, Medical Zoology Department, NAMRU-3.) Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Medical Entomology, Volume 20, Issue 5, 5 October 1983, Pages 534–540, https://doi.org/10.1093/jmedent/20.5.534 Published: 05 October 1983

Journal Article Mating Regulation and Reproductive Isolation in the Ticks Hyalomma Dromedarii and H. Anatolicum Excavatum (Acari: Ixodoidea: Ixodidae) Get access Galila M. Khalil, Galila M. Khalil 3Medical Zoology Department, Naval Medical Research Unit Number Three (NAMRU-3), American Embassy, Cairo, Arab Republic of Egypt Search for other works by this author on: Oxford Academic PubMed Google Scholar Daniel E. Sonenshine, Daniel E. Sonenshine 4Department of Biological Sciences, Old Dominion University, Norfolk, Virginia 23508, USA Search for other works by this author on: Oxford Academic PubMed Google Scholar Omniat A. Sallam, Omniat A. Sallam 3Medical Zoology Department, Naval Medical Research Unit Number Three (NAMRU-3), American Embassy, Cairo, Arab Republic of Egypt Search for other works by this author on: Oxford Academic PubMed Google Scholar Paul J. Homsher Paul J. Homsher 4Department of Biological Sciences, Old Dominion University, Norfolk, Virginia 23508, USA Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Medical Entomology, Volume 20, Issue 2, 30 March 1983, Pages 136–145, https://doi.org/10.1093/jmedent/20.2.136 Published: 30 March 1983