Resistance profile and molecular characterization of pyrethroid resistance in a Rhipicephalus microplus strain from Colombia.

Intensive use of chemical acaricides for the control of cattle ticks (Rhipicephalus microplus) has led to the development of multiple acaricide resistance in Colombia. The present study aimed to characterize, using toxicological bioassays and molecular biology techniques, the resistance profile of a tick strain isolated from the Arauca state, Northeast Colombia. Commercial acaricides were used in adult immersion tests to determine its in vitro efficacies. Deltamethrin showed very low activity (4-7.3%), a mixture of cypermethrin and chlorpyrifos had intermediate efficacy (64-75.2%), and ethion presented the highest activity (88.5-100%). A colony (Arauquita strain) was established and larval immersion tests confirmed high resistance level to deltamethrin (241-fold) and susceptibility to ivermectin. A quantitative polymerase chain reaction-high resolution melt technique was used to identify single nucleotide polymorphisms (SNPs) in the para-sodium channel gene. All of the genotyped individuals were mutant, presenting one (n = 7), two (n = 7) or three (n = 9) SNPs previously associated with pyrethroid resistance. Sequencing revealed a novel mutation (F712L), that was found for the first time in R. microplus ticks from South America. This is the first description of mutations associated with pyrethroid resistance in R. microplus from Colombia. The acaricide resistance pattern found in the Arauquita strain is similar to other parts of Colombia.

Metabolic rates and thermal conductance in four species of neotropical bats roosting in hot caves.

Data are presented on metabolic rates and thermal conductance for four species of neotropical bats, Pteronotus quadridens, Mormoops blainvillii (Mormoopidae), Monophyllus redmani and Erophylla bombifrons (Phyllostomidae). Each of these bats predominantly or exclusively roosts in hot caves (28-40 degrees C) in Puerto Rico. Basal metabolic rates (BMR) for these four species were 55%, 48%, 66%, and 66% of values expected from the Kleiber curve, respectively. Thermal conductance was 93%, 55%, 175%, and 158% of values expected from the Aschoff curve, respectively. These data indicate that, in addition to food habits, variation in BMR is highly correlated to roost microclimate. Pteronotus and Mormoops, like other insectivorous species, have low BMRs. The low BMR of the nectar/fruit eating Monophyllus and Erophylla, as well as the low termal conductance in Mormoops, is consistent with their habit of roosting in hot caves, suggesting that roost microclimate is an important selective force in the physiological adaptation of these bats.