Thanispong Kanutcharee, Sathantriphop Sunaiyana, Tisgratog Rungarun, Tainchum Krajana, Sukkanon Chutipong, Bangs Michael J, Chareonviriyaphap Theeraphap
Department of Disease Control, Bureau of Vector-Borne Diseases, Ministry of Public Health, Nonthaburi 11000, Thailand.
Department of Medical Sciences, National Institute of Health, Ministry of Public Health, Nonthaburi 11000, Thailand.
J Econ Entomol. 2018 Sep 26;111(5):2375-2382. doi: 10.1093/jee/toy199.
Malaria is a serious mosquito-borne disease transmitted to humans by Anopheles mosquitoes. Seven species of Anopheles are important malaria vectors in Thailand and all remain susceptible to pyrethroid insecticides, despite decades of use in public health mosquito control programs. However, for a more refined and accurate approach to temporal monitoring of susceptibility patterns to commonly used pyrethroids to control adult Anopheles mosquitoes, it is preferred to have specific concentrations for more discriminating testing. A laboratory strain of Anopheles minimus Theobald was used to establish baseline concentrations for susceptibility to six different synthetic pyrethroids-deltamethrin, permethrin, bifenthrin, cypermethrin, α-cypermethrin, and λ-cyhalothrin using the World Health Organization (WHO) adult bioassay system. Final discriminating concentrations of each active ingredient were determined based on doubling LC99 for each chemical to arrive at the following percent concentrations: deltamethrin (0.009%), permethrin (0.551%), bifenthrin (0.12%), cypermethrin (0.104%), α-cypermethrin (0.034%), and λ-cyhalothrin (0.019%). For permethrin, deltamethrin, α-cypermethrin, and λ-cyhalothrin, all revised percentages were lower than currently recommended discriminating concentrations by WHO. Using the newly derived concentrations, insecticide susceptibility tests were followed in a field population of An. minimus s.l. from Kanchanaburi Province. Deltamethrin, bifenthrin, and λ-cyhalothrin produced 100% kill, whereas permethrin, cypermethrin, and α-cypermethrin gave between 92.9 and 97.7% mortality, indicating lower sensitivity (tolerance). Routine monitoring of insecticide susceptibility in An. minimus wild populations throughout Thailand should continue to ensure that insecticides in use are effective to control this vector species.
疟疾是一种由按蚊传播给人类的严重蚊媒疾病。在泰国，七种按蚊是重要的疟疾传播媒介，尽管在公共卫生灭蚊项目中已使用拟除虫菊酯类杀虫剂数十年，但它们对这类杀虫剂仍敏感。然而，为了采用更精细、准确的方法对常用拟除虫菊酯类杀虫剂控制成年按蚊的敏感性模式进行时间监测，最好有特定浓度用于更具区分性的测试。使用世界卫生组织（WHO）的成蚊生物测定系统，以微小按蚊实验室品系来确定对六种不同合成拟除虫菊酯——溴氰菊酯、氯菊酯、联苯菊酯、氯氰菊酯、α-氯氰菊酯和高效氯氟氰菊酯的敏感性基线浓度。每种活性成分的最终区分浓度是根据每种化学物质的LC99加倍来确定的，得出以下百分比浓度：溴氰菊酯（0.009%）、氯菊酯（0.551%）、联苯菊酯（0.12%）、氯氰菊酯（0.104%）、α-氯氰菊酯（0.034%）和高效氯氟氰菊酯（0.019%）。对于氯菊酯、溴氰菊酯、α-氯氰菊酯和高效氯氟氰菊酯，所有修订后的百分比均低于WHO目前推荐的区分浓度。使用新得出的浓度，对北碧府微小按蚊复合组的野外种群进行了杀虫剂敏感性测试。溴氰菊酯、联苯菊酯和高效氯氟氰菊酯的杀灭率为100%，而氯菊酯、氯氰菊酯和α-氯氰菊酯的死亡率在92.9%至97.7%之间，表明敏感性较低（耐受性）。应继续对泰国各地微小按蚊野生种群的杀虫剂敏感性进行常规监测，以确保所使用的杀虫剂对控制这种病媒物种有效。
