Use of biotherapic in the control of the natural infestation by Boophilus microplus: pilot study / Uso do bioterapico no controle da infestação natural por Boophilus microplus: estudo piloto

In the control of tick-borne disease (TBD), resistance to chemical products has been reported and a concern with the preservation of the environment requires alternative procedures to control infestation by Boophilus microplus worldwide. The use of biotherapic preparations is one of such alternatives. The aim of this study was to evaluate the effects of a biotherapic mixture including B. microplus in naturally infested cattle. 27 animals were divided in 3 groups (n=9): I – control, received no treatment; II- treated with amitraz dip; III- treated with a standard commercial mixture of biotherapic 12cH, p.o. Group III presented a statistically significant decrease of ticks when compared to the control group (p < 0.05). There was no statistically significant difference between groups II (amitraz) and III (biotherapic) (p < 0.05). These results suggest that biotherapic preparations might be effective in the control of B. microplus in cattle.(AU)

No controle de enfermidades transmitidas por carrapatos tem sido notada a resistência a produtos químicos. A preocupação com a conservação do meio ambiente tem exigido procedimentos alternativos para controlar a infestação por Boophilus microplus, em todo o mundo. O uso de bioterápicos representa uma dessas alternativas. O objetivo deste estudo foi avaliar o efeito de uma mistura de bioterápicos incluindo B. microplus, em gado bovino infestado naturalmente. 27 animais foram divididos em 3 grupos (n=9): I) controle sem tratamento; II) tratado com banho de amitraz; III) tratado com mistura comercial de bioterápicos 12 cH, via oral. O grupo III apresentou uma diminuição estatísticamente significativa de carrapatos, em comparação com grupo controle (p < 0,05). Não houve diferença significativa entre os grupo II e III (p < 0,05). Estes resultados sugerem que os preparados de bioterápicos podem ser eficazes para o controle de B. microplus em bovinos.(AU)

Use of biotherapic in the control of the natural infestation by Boophilus microplus: pilot study / Uso do bioterapico no controle da infestação natural por Boophilus microplus: estudo piloto

In the control of tick-borne disease (TBD), resistance to chemical products has been reported and a concern with the preservation of the environment requires alternative procedures to control infestation by Boophilus microplus worldwide. The use of biotherapic preparations is one of such alternatives. The aim of this study was to evaluate the effects of a biotherapic mixture including B. microplus in naturally infested cattle. 27 animals were divided in 3 groups (n=9): I – control, received no treatment; II- treated with amitraz dip; III- treated with a standard commercial mixture of biotherapic 12cH, p.o. Group III presented a statistically significant decrease of ticks when compared to the control group (p < 0.05). There was no statistically significant difference between groups II (amitraz) and III (biotherapic) (p < 0.05). These results suggest that biotherapic preparations might be effective in the control of B. microplus in cattle.

No controle de enfermidades transmitidas por carrapatos tem sido notada a resistência a produtos químicos. A preocupação com a conservação do meio ambiente tem exigido procedimentos alternativos para controlar a infestação por Boophilus microplus, em todo o mundo. O uso de bioterápicos representa uma dessas alternativas. O objetivo deste estudo foi avaliar o efeito de uma mistura de bioterápicos incluindo B. microplus, em gado bovino infestado naturalmente. 27 animais foram divididos em 3 grupos (n=9): I) controle sem tratamento; II) tratado com banho de amitraz; III) tratado com mistura comercial de bioterápicos 12 cH, via oral. O grupo III apresentou uma diminuição estatísticamente significativa de carrapatos, em comparação com grupo controle (p < 0,05). Não houve diferença significativa entre os grupo II e III (p < 0,05). Estes resultados sugerem que os preparados de bioterápicos podem ser eficazes para o controle de B. microplus em bovinos.

[The impact of electromagnetic radiation at microwave frequency (9.8 HhZ)on the embryonic and postembryonic development of the tick Hyalomma asiaticum (Acarina, Ixodidae)]. / Vliianie élektromagnitnogo izlucheniia svch diapazona (9.8 ggts) na émbrional'noe i postémbrional'noe razvitie kleshcha Hyalomma asiaticum (Acarina, Ixodidae).

Low-power (20 microW/cm2) microwave-modulated radiation at a carrier frequency of 9.8 Hhz is shown to affect the course and specific features of ontogenesis of the ick H. asiaticum. The actin of microwave radiation on the development of H. asiaticum substantially depends on the frequency of microwave modulation of a signal and on the temperatures of an experiment. When the temperature is 22 degrees C, there is a significant suppression of development of fed larvae and nymphs after exposure to microwave radiation at modulated signal frequencies of 3 and 5 Hz/ The whole range of the tested modulation frequencies was 2 to 16 Hz. The hungry species of all developmental phases in H. asiaticum were virtually unresponsive to exposures. At 14 degrees C (a perithreshold temperature of H. asiaticum development), the action of microwave radiation changed from inhibitory to stimulating. At modulation frequencies of 3, 5 and 7 Hz, the proportion of hatching larvae was 42.5, 67.5 and 80.0%, respectively, and that of controls was 2.5%. Whether the size of a H.asiaticum population can be controlled by a radar that provokes the development of ticks before winter by its radiation is discussed.

[The reaction of the tick Hyalomma asiaticum (Acarina, Ixodidae) to 1- to 4-GHz microwaves]. / Reaktsiia kleshscha Hyalomma asiaticum (Acarina, Ixodidae) na mikrovolny 1--4 GGts.

Low-energy microwave radiation in the frequency range in question was found to exert a noticeable biological action on H. asiaticum. Radiation delayed larval hatch by 3-20 days, increased the activity duration of newly moulted larvae by 17-24 days, reduces the survival of hungry larvae and nymphs by 4-10 days. The efficiency of the biological action of microwaves is enhanced by impairments in the natural developmental rhythm of the tick.

Photoperiodic response in the soft tick, Ornithodoros turicata.

The effects of photoperiod on the feeding, development and quiescent behavior of the burrow-dwelling soft tick, Ornithodoros turicata (Dugès) were investigated. Ticks were assigned randomly to either continuous darkness (DD), a short-day photoperiod (L:D 10:14), a long-day photoperiod (L:D 14:10) or constant light (LL). Ticks reared under constant light succumbed to much higher mortality than those reared under the other conditions. However, photoperiod did not induce quiescent behavior in O. turicata; the ticks were active and fed regularly throughout the study. Also, ticks reared in continuous darkness developed more slowly than those reared under short-day or long-day conditions. In contrast, pre-oviposition period was significantly longer for ticks reared in long-day conditions. Egg-hatch success was significantly higher for ticks reared in continuous darkness than for those reared under the photoperiods. The stage-specific effects of photoperiod on O. turicata are adaptive; these ticks very likely utilize photoperiod information to predict seasonal conditions.

On the reaction of adult Rhipicephalus evertsi mimeticus and Hyalomma truncatum to horizontally incidenting optical radiation of various wavelengths ranges and different irradiances and to optical radiation of a sun-simulating wavelength spectrum.

The valence of horizontally incidenting light/optical radiation for host-seeking-inclined ixodid ticks was investigated by exposing male and female adults of Rhipicephalus evertsi mimeticus and Hyalomma truncatum to narrow-band monochromatic radiation in the wavelength range of 300-801 nm at irradiances corresponding to an overcast to clear sunny day, a cloudy day and a full-moon night as well as to optical radiation of a sun-simulating wavelength spectrum of 190-2600 nm within a test chamber from which other stimuli were excluded. It was demonstrated that independent of sex, adult ticks of R. e. mimeticus and H. truncatum responded to a wide wavelength spectrum in the visible and UV range, even at irradiances corresponding to a full-moon night. Interspecific differences existed in the degree and extent of the response as well as in the spectral sensitivity. Ticks of H. truncatum consistently showed a faster and stronger response and reacted phototactically positively in higher percentages than adults of R. e. mimeticus. Independent of wavelength range and irradiance, predominantly only few R. e. mimeticus ticks were stimulated to positive phototaxis, whereas at least 33.3% (in most cases, 50%) and maximally greater than 80% of H. truncatum adults reacted phototactically positively. Spectral sensitivity maxima were demonstrated at the yellow and red light and at the UV-A waveband width for R. e. mimeticus and at the violet, blue, green and yellow light wavelength for H. truncatum. With decreasing irradiance, the spectral sensitivity shifted to the blue wavelength range.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of gamma radiation on spermatogenesis and fertility of male Amblyomma americanum (Acari: Ixodidae).

Amblyomma americanum males were treated with 0.5, 1, 2, 3, 4, 8, and 16 krad of gamma radiation. Testes of ticks treated with 2, 3, 4, 8, and 16 krad were smaller than those of ticks irradiated at lower levels and controls. No recognizable alteration in timing of spermatogenesis was noted among the different radiation groups, but severe breakdown and depletion of germinal cells was noted at 4, 8, and 16 krad. Percent hatch of larvae from crosses of irradiated males and untreated females decreased with increasing radiation level. No hatch was observed from eggs of females mated to males treated at 2 krad or higher.

The effect of irradiation on the susceptibility of Rhipicephalus appendiculatus ticks to Theileria parva infection.

Irradiation doses of 800 rad. or less had no detectable effect on the subsequent development of unfed nymphal Rhipicephalus appendiculatus ticks. Doses of 1600 rad. or above impaired feeding and moulting and delayed the subsequent development of unfed nymphs. At 6400 rad. no ticks completed their moult. Unfed nymphal R. appendiculatus irradiated at 0, 400, 800 and 1600 rad. were applied to 3 cattle infected with T. parva (Kiambu 4). The Theileria infections in the salivary glands of the resultant adult ticks were assessed and it was found that irradiation doses of 800 rad. or less had little effect on the Theileria infections, but an irradiation dose of 1600 rad. greatly reduced the level of infection. The numbers of salivary gland acini in ticks of this group were reduced but the percentage of infected acini was similar.

Some effects of 60Co irradiation on Cowdria ruminantium in its tick host Amblyomma hebraeum Koch (Acarina: Ixodidae).

An attempt was made to attenuate Cowdria ruminantium by irradiation of the nymphal stage of its tick host, Amblyomma hebraeum. The irradiated nymphs were homogenized and serial dilutions of the resultant suspension were injected intravenously into heartwater-susceptible sheep. No attenuation could be demonstrated but the results indicate that progressively more micro-organisms will be destroyed the higher the irradiation dosage applied, and that dosages between 20 and 30 kilorad apparently prove fatal to all the pathogenic organisms.

The subgenus Persicargas (Ixodoidea: Argasidae: Argas). 33. Effect of gamma radiation on first nymphal instar A. (P.) arboreus and adult fertility.

Gamma radiation doses higher than 1,000 rads are lethal to first nymphal instar Argas (Persicargas) arboreus. Only 50% of first nymphal instars receiving 1,000 rads reach adulthood but those receiving 100-500 rads survive normally. Males resulting from irradiated first nymphal instars are almost normally fertile. Female germinal cells tolerate higher radiation doses received in the first nymphal instar stage than in the adult stage. Females resulting from first nymphal instars receiving does higher than 100 rads are less fertile (egg number and percent hatch) than normal and produce F1 larvae of lower than normal viability. Progenies of females irradiated as nymphs apparently inherit lethal genes, which may be useful, if irradiated at critical stages, in tick control.

Effects of 60Co irradiation on Amblyomma hebraeum Koch, 1844 (Acarina: Ixodidae).

The effects of 60Co irradiation on Amblyomma hebraeum Koch, 1844 were studied by mating normal females to males irradiated to attain dosages of 0, 2, 4, 6 and 8 kilorad. The males of all 5 groups were observed mating 7 days after being placed on the host. The higher the irradiation dosage received by the males, progressively longer were the feeding periods of the females mated with them and fewer completed their engorgement. Furthermore, the mass of the females when engorged was lower, fewer laid eggs and the number of eggs they laid decreased progressively. None of the egg batches produced by females mated with irradiated males hatched. No chromosomal abnormalities or discrepancies in spermiophore formation were found in the 2 and 4 kilorad group males, while no micro- or macroscopical growth of the 6 and 8 kilorad group male testes took place, although accessory gland development appeared normal. A. hebraeum males have a chromosome complement of 10 bivalents and a univalent sex chromosome.

Effects of 60Co irradiation on unfed adults and engorged females of the tick Hyalomma anatolicum.

Unfed and engorged adults of the cattle tick Hyalomma anatolicum, known to be biological vector of Theileria anmulata in India, were exposed to various levels of gamma-radiation from 0-60 000 R, and the effect on engorgement and redproduction was observed. The radiation tolerance limit for unfed adults is 1000 R for engorgement and reproduction. The sterilizing dose for most of the males is 2000 R but the females can tolerate a slightly higher dose. Engorged females have a tolerance limit of 10 000 R for oviposition and 1000 R for larval development. Higher dosages (20 000-60 000 R) have adverse effects on development, completely inhibiting egg-laying at 60 000 R, but these females (60 000 R) live longer (10 weeks) than those irradiated at lower levels.

Effects of 60Co irradiation of the early developmental stages of an ixodid tick, Hyalomma anatolicum.

Various developmental stages of Hyalomma anatolicum were subjected to a range of doses of 60Co radiation from 0-10 000 R, and their subsequent development was observed. Some of these ticks were infected with Theileria annulata. Doses of 2000 R and over prevented all but a very limited development of ticks. After 1000 R a proportion of exposed individuals continued development in a near-normal manner. Lower doses had proportionately less effect. 1000 R to ticks infected with T. annulata failed to prevent transmission of typical theileriasis to calves.