Effects of prolonged exposure at low temperature on Boophilus microplus (Acari: Ixodidae)

The effects of prolonged exposure at 12 degrees C on oviposition were determined for Boophilus microplus (Canestrini) females. The percentage of females ovipositing remained high (greater than or equal to 80%) for exposure times of less than or equal to 30 d, but declined to 0.0 and 6.7% when females were held for 90 and 105 d, respectively. Duration had no effect on the preoviposition period after females were returned to optimum temperature (25 degrees C). The number of eggs laid per female declined at each exposure interval between 15 d, where no significant adverse effect on egg deposition was noted, and 90 d, where no eggs were laid. The hatch of eggs derived from exposed females showed a similar decline as the exposure time increased. A strong negative relationship between exposure time and egg viability was observed for eggs deposited at optimum temperature and then exposed to low temperature at intervals of 0 to 105 d. Larval longevity also showed a substantial negative relationship to exposure time. Results of the investigation and differences noted to results with B. annulatus (Say) also are discussed.