SURVIVAL OF LARVAE OF BOOPHILUS-ANNULATUS, BOOPHILUS-MICROPLUS, AND BOOPHILUS HYBRIDS (ACARI, IXODIDAE) IN DIFFERENT TEMPERATURE AND HUMIDITY REGIMES IN THE LABORATORY

The survival period for larvae of Boophilus annulatus (Say), Boophilus microplus (Canestrini) and hybridized Boophilus ticks was determined by exposure to various combinations of temperature (20, 25, 30 and 35-degrees-C) and relative humidity (32, 63, 75, 84 and 97% RH) in the laboratory. Results indicated that within a given temperature and RH regime, there was no difference (P > 0.05) in larval survival among the three species tested, indicating that these ticks respond similarly over a wide range of temperature and RH combinations. Larval survival in all three species was longest (P < 0.05) at 20-degrees-C and either 84 or 97% RH. With each increase in temperature at the 84 and 97% RH treatment levels, there was a corresponding significant (P < 0.05) decrease in larval survival. When the temperature reached 35-degrees-C at all humidities or when the RH was 63% or less at all temperatures, the mean larval survival period was 43 days or less in all cases and little difference (P > 0.05) was observed among the treatment regimes included. Results suggest that at a RH of 75% and more, the temperature is the determining factor in larval survival, whereas at a RH of 63% and less the RH is the determining factor in larval survival, regardless of temperature.