<b>Objective:</b> The objective is to<span "=""> compare a regular ovitrap versus an innovated larvitrap for monitoring <i>Aedes</i> spp. populations. <b>Materials an...<b>Objective:</b> The objective is to<span "=""> compare a regular ovitrap versus an innovated larvitrap for monitoring <i>Aedes</i> spp. populations. <b>Materials and Methods</b></span><b>:</b><span "=""> A total of 20 regular ovitraps and 20 innovated larvitraps were placed in pairs in 20 houses from the 5 de Febrero neighborhood in Tapachula, Chiapas, Mexico. The innovation consisted in the incorporation of a valve in the lower part of a half tire to drain the contents in a 2 L collection container. The evaluation was carried out during five weeks, collecting eggs and larvae from the ovitraps and innovated larvitraps, respectively. Positivity indexes and insectary production of adult <i>Aedes</i> spp. mosquitoes were compared by collection type. <b>Results</b></span><b>:</b><span "=""> Average positivity index for the five weeks period were 60% for ovitraps and 91.25% for innovated larvitraps. During the five weeks, 4043 <i>Ae.</i> <i>aegypti</i> and 703 <i>Ae.</i> <i>albopictus</i> adult mosquitoes were produced in the insectary from the eggs collected from ovitraps, while from innovated larvitraps were 9014 <i>Ae.</i> <i>aegypti</i>, 1205 <i>Ae.</i> <i>albopictus</i>, and 15 <i>Culex</i> spp. <b>Conclusion</b></span><b>:</b><span "=""> Collection by the innovated larvitrap was more efficient, collecting 3.56 times more <i>Ae.</i> <i>aegypti</i> than with ovitraps, using approximately the same effort in time for replacing the filter paper from traditional 1 L ovitraps. Since the logistics for the storage and placement of larvitraps may still be a disadvantage in comparison with ovitraps, their use could be specifically intended in sentinel sites for mosquito population monitoring for entomological surveillance purposes.展开更多
Background: Despite the physical and chemical effort to control Aedes aegypti, the arboviruses transmission in the south of Mexico remains latent. Trying to improve the methods of entomological surveillance routinely ...Background: Despite the physical and chemical effort to control Aedes aegypti, the arboviruses transmission in the south of Mexico remains latent. Trying to improve the methods of entomological surveillance routinely used, whether the estimation of resistance to insecticides used for its control, as well as their enzyme mechanisms, were influenced by the phase in which the mosquitoes were collected through three different collection methods was investigated. Materials and Methods: Mosquito collections from the “5 de Febrero” neighborhood in Tapachula, Mexico were obtained by ovitraps, larvitraps, and a CDC backpack aspirator. Insecticide resistance of F<sub>1</sub> females was determined by WHO diagnostic doses and resistance ratios (RR<sub>50</sub>), furthermore, levels of insecticide metabolism enzymes were determined by biochemical assays. Results: Overall, in mosquitoes collected by ovitraps, larvitraps, and CDC backpack aspirator respectively, the low mortalities obtained with the discriminant dose to Malathion (27.57%, 26.97%, and 26.91%), and to Bendiocarb (50.5%, 45.36%, and 54.97%) suggest resistance. However, LC<sub>50</sub> for Malathion (0.922, 0.934, and 0.915) and for Bendiocarb (0.112, 0.109, and 0.107);and the low resistance ratios (RR<sub>50</sub>) for Malathion (3.34, 3.29, and 3.27) and for Bendiocarb (2.15, 2.1, and 2.06) does not suggest resistance. Although a slight numerical variation is observed between the three LC<sub>50</sub> values, the overlap observed between their confidence intervals allows us to assume that there were no differences between the three methods. In general, esterases (determined with three substrates), glutathion S-transferases (GST) and cytochromes P<sup>450</sup> were statistically higher than those of the susceptible strain;and the three enzyme levels were statistically different among the three collection methods (P Conclusion: Although using a CDC backpack aspirator demonstrated being the best collection method determining a specific resistance mechanism (as elevation at the enzyme level) in the mosquito adult phase, any collection method is reliable to determine whether a field mosquito population is resistant or susceptible to an insecticide.展开更多
文摘<b>Objective:</b> The objective is to<span "=""> compare a regular ovitrap versus an innovated larvitrap for monitoring <i>Aedes</i> spp. populations. <b>Materials and Methods</b></span><b>:</b><span "=""> A total of 20 regular ovitraps and 20 innovated larvitraps were placed in pairs in 20 houses from the 5 de Febrero neighborhood in Tapachula, Chiapas, Mexico. The innovation consisted in the incorporation of a valve in the lower part of a half tire to drain the contents in a 2 L collection container. The evaluation was carried out during five weeks, collecting eggs and larvae from the ovitraps and innovated larvitraps, respectively. Positivity indexes and insectary production of adult <i>Aedes</i> spp. mosquitoes were compared by collection type. <b>Results</b></span><b>:</b><span "=""> Average positivity index for the five weeks period were 60% for ovitraps and 91.25% for innovated larvitraps. During the five weeks, 4043 <i>Ae.</i> <i>aegypti</i> and 703 <i>Ae.</i> <i>albopictus</i> adult mosquitoes were produced in the insectary from the eggs collected from ovitraps, while from innovated larvitraps were 9014 <i>Ae.</i> <i>aegypti</i>, 1205 <i>Ae.</i> <i>albopictus</i>, and 15 <i>Culex</i> spp. <b>Conclusion</b></span><b>:</b><span "=""> Collection by the innovated larvitrap was more efficient, collecting 3.56 times more <i>Ae.</i> <i>aegypti</i> than with ovitraps, using approximately the same effort in time for replacing the filter paper from traditional 1 L ovitraps. Since the logistics for the storage and placement of larvitraps may still be a disadvantage in comparison with ovitraps, their use could be specifically intended in sentinel sites for mosquito population monitoring for entomological surveillance purposes.
文摘Background: Despite the physical and chemical effort to control Aedes aegypti, the arboviruses transmission in the south of Mexico remains latent. Trying to improve the methods of entomological surveillance routinely used, whether the estimation of resistance to insecticides used for its control, as well as their enzyme mechanisms, were influenced by the phase in which the mosquitoes were collected through three different collection methods was investigated. Materials and Methods: Mosquito collections from the “5 de Febrero” neighborhood in Tapachula, Mexico were obtained by ovitraps, larvitraps, and a CDC backpack aspirator. Insecticide resistance of F<sub>1</sub> females was determined by WHO diagnostic doses and resistance ratios (RR<sub>50</sub>), furthermore, levels of insecticide metabolism enzymes were determined by biochemical assays. Results: Overall, in mosquitoes collected by ovitraps, larvitraps, and CDC backpack aspirator respectively, the low mortalities obtained with the discriminant dose to Malathion (27.57%, 26.97%, and 26.91%), and to Bendiocarb (50.5%, 45.36%, and 54.97%) suggest resistance. However, LC<sub>50</sub> for Malathion (0.922, 0.934, and 0.915) and for Bendiocarb (0.112, 0.109, and 0.107);and the low resistance ratios (RR<sub>50</sub>) for Malathion (3.34, 3.29, and 3.27) and for Bendiocarb (2.15, 2.1, and 2.06) does not suggest resistance. Although a slight numerical variation is observed between the three LC<sub>50</sub> values, the overlap observed between their confidence intervals allows us to assume that there were no differences between the three methods. In general, esterases (determined with three substrates), glutathion S-transferases (GST) and cytochromes P<sup>450</sup> were statistically higher than those of the susceptible strain;and the three enzyme levels were statistically different among the three collection methods (P Conclusion: Although using a CDC backpack aspirator demonstrated being the best collection method determining a specific resistance mechanism (as elevation at the enzyme level) in the mosquito adult phase, any collection method is reliable to determine whether a field mosquito population is resistant or susceptible to an insecticide.
