Effect of surface area to weight ratio of egg masses on the hatchability of Boophilus microplus eggs.

BACKGROUND & OBJECTIVES: On global basis, ticks transmit a number of pathogens than any other arthropod vector, and are among the most important vectors of diseases affecting humans, livestock and companion animals. Control of the vector has been focused on integrated management involving strategic use of insecticides, use of vaccines, use of herbal acaricides and breed resistance. It has been established that tick vaccine is working on limiting the egg laying potentiality and subsequent hatchability of the ticks fed on immunized animals. To generate entomological data following immunization of animals against ticks an experiment was conducted to establish the role of water content in egg masses for successful hatching into larvae. METHODS: Different size and shape of egg masses of Boophilus microplus, Izatnagar isolate were obtained by manipulating the egg laying process. The weight of the egg masses was measured, keeping their integrity and surface areas of respective egg masses were calculated with the aid of computer software. Larvae hatched from the respective egg masses were counted individually. RESULTS: It is clear that, with an increase in the exposed surface area of the cylindrical egg mass per unit weight, there is a reduction in the number of larvae hatched out. Also, the spherical egg masses significantly (0.026 at 95% confidence level) yielded more larvae per unit weight in comparison to the cylindrical egg masses. INTERPRETATION & CONCLUSION: It has been established that the larval count yielded from an egg mass is more or less dependent on the surface area : weight ratio of the respective egg masses rather than on either the surface area alone or weight of the egg mass alone.

Two human cases of tick bite caused by Ixodes nipponensis

We report two human cases of tick bite. A 63-year-old male had a pruritic pea-sized brownish nodule on the left popliteal area. Another 41-year-old male had an asymptomatic bean-sized black nodule in the pubic area. The ticks were identified as Ixodes nipponensis, which are the 18th and the 19th cases in Korea.

Seasonal analysis of the number of aeropiles in Anocentor nitens (Neumann, 1897) (Acari: Ixodidae) from the State of Rio de Janeiro, Brazil

Variation between aeropile numbers of the right and left peritrematic plate in male and female Anocentor nitens (Neumann, 1897) is reported from a site in Brazil. From January to December 1998, 146 males and 247 females of A. nitens were recovered from Equus caballus L. in Silva Jardim District, State of Rio de Janeiro. Asymmetry of numbers of aeropiles between right and left plates occurred in 83.6 percent of the males and 82.2 percent of the females. Differences in the number of aeropiles between the sexes were not significant. Quantitative variation of aeropiles was correlated to the period of recovery, with significant asymmetry detected in August-September and November-December, mainly in males. Results suggest an adaptation, especially in the male ticks, that expresses itself as greater variation in the number of aeropiles in some periods of the year