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1.
Am J Trop Med Hyg ; 104(3): 1111-1122, 2021 01 11.
Article in English | MEDLINE | ID: mdl-33432904

ABSTRACT

The status of insecticide resistance in Aedes aegypti is of concern in areas where Aedes-borne arboviruses like chikungunya, dengue, and Zika occur. In recent years, outbreaks involving these arboviruses have occurred, for which vaccines do not exist; therefore, disease prevention is only through vector control and personal protection. Aedes aegypti are present on every inhabited island within the Florida Keys. The resistance status of Ae. aegypti in the Florida Keys was assessed to guide knowledge of the best choice of chemical for use during an outbreak. Mosquito eggs were collected using ovitraps placed on Key West, Stock Island, Vaca Key, Upper Matecumbe Key, Plantation Key, and Key Largo. Bottle bioassays were conducted at the Florida Keys Mosquito Control District using Biomist® 30+30 (Clarke Mosquito Control Products, Inc., Roselle, IL). Further bottle testing using malathion and permethrin occurred at the CDC, Fort Collins, CO, in addition to molecular and biochemical assays. Levels of resistance varied between islands with different underlying mechanisms present. Resistance was seen to Biomist® 30+30 but not to permethrin, indicating that piperonyl butoxide (PBO) or the inert ingredients may be involved in resistance. No study has been conducted to date examining the role of PBO in resistance. Key Largo was treated the most with adulticides and expressed the highest levels of alpha and beta esterases, oxidases, glutathione-S-transferases, and frequency of the V1016I knockdown mutation from all sites tested. Knowledge of localized resistance and underlying mechanisms helps in making rational decisions in selection of appropriate and effective insecticides.


Subject(s)
Aedes/drug effects , Aedes/genetics , Insecticide Resistance/drug effects , Insecticide Resistance/genetics , Insecticides/pharmacology , Mosquito Control , Pyrethrins/pharmacokinetics , Animals , Florida , Genetic Variation , Genotype , Mosquito Vectors/drug effects , Mosquito Vectors/genetics , Phenotype
2.
J Am Mosq Control Assoc ; 33(1): 8-15, 2017 Mar.
Article in English | MEDLINE | ID: mdl-28388320

ABSTRACT

During the 2014 chikungunya (CHIK) outbreak in the Caribbean, we performed entomological surveys on 3 United States Virgin Islands (USVI): St. Croix, St. Thomas, and St. John. We aimed to evaluate the potential for chikungunya virus (CHIKV) transmission in the USVI. The surveys took place between June 19, 2014, and June 29, 2014, during the dry season in USVI. A total of 1,929 adult mosquitoes belonging to 4 species- Culex quinquefasciatus (68.4%), Aedes aegypti (29.7%), Ae. mediovittatus (1.3%), and Ae. sollicitans (<1%)-were detected. Environmental investigations showed that between 73% and 87% of the homes had containers that could serve as mosquito larval habitats. In addition, 47% of the homes did not have air conditioning and between 69% and 79% of homes showed evidence of frequent outdoor activity exhibited by residents. Taken together, these observations suggest a high potential for CHIKV transmission in USVI. The relative abundance of Ae. aegypti on St. John's, St. Thomas, and St. Croix was 21.0, 11.0, and 3.0 mosquitoes/trap per day, respectively, suggesting that the former 2 islands were at the highest risk of CHIKV outbreaks. Insecticide resistance testing detected high levels of resistance to malathion and permethrin in several local populations of Ae. aegypti on St. Croix Island, which suggested that these 2 insecticides should not be used during CHIK outbreaks.


Subject(s)
Aedes/physiology , Chikungunya Fever/transmission , Culex/physiology , Insecticide Resistance , Mosquito Vectors/physiology , Animals , Chikungunya virus/physiology , Female , Population Dynamics , Risk Assessment , United States Virgin Islands
3.
J Med Entomol ; 54(3): 785-787, 2017 05 01.
Article in English | MEDLINE | ID: mdl-28031346

ABSTRACT

Insecticides based on botanical sources have taken on increased attention due to differing modes of action from current insecticides in use and the view that they may be environmentally friendly. Thymoquinone, a component in the essential oil of incense cedar heartwood, has been shown to have insecticidal action against adult mosquitoes. This study evaluated relative toxicities of thymoquinone, selected derivatives of thymoquinone, hydroquinone, and arbutin to determine if any had similar or better activity. The intrinsic toxicities of hydroquinone and thymohydroquinone were not significantly different from thymoquinone, while libocedrol and arbutin were significantly less toxic.


Subject(s)
Culex/drug effects , Insecticides/pharmacology , Animals , Arbutin/pharmacology , Benzoquinones/pharmacology , Female , Hydroquinones/pharmacology , Thymol/analogs & derivatives , Thymol/pharmacology
4.
J Vector Ecol ; 37(2): 325-32, 2012 Dec.
Article in English | MEDLINE | ID: mdl-23181855

ABSTRACT

In Port-au-Prince, Haiti, the status of insecticide resistance has not recently been evaluated for Aedes aegypti (L) and Aedes albopictus (Skuse) populations. No prophylactics exist for dengue, so prevention is only through vector control methods. An earthquake occurred in Haiti on January 12, 2010, with a magnitude of 7.0 Mw that devastated the area. Dengue became a major concern for the humanitarian relief workers that entered the country. Bottle bioassays were conducted in the field on adult mosquitoes reared from larvae collected from the grounds of the U.S. Embassy and from an adjacent neighborhood in eastern Port-au-Prince, Haiti. At the CDC, Fort Collins, CO, bioassays, molecular, and biochemical assays were performed on mosquitoes reared from field-collected eggs. A small percentage of the population was able to survive the diagnostic dose in bioassays run in Haiti. Mosquitoes tested at the CDC demonstrated no phenotypic resistance. A variety of factors could be responsible for the discrepancies between the field and lab data, but temperature and larval nutrition are probably most important. Knowledge of localized resistance and underlying mechanisms helps in making rational decisions in selection of appropriate and effective insecticides in the event of a dengue outbreak.


Subject(s)
Aedes/drug effects , Pyrethrins/pharmacology , Animals , Biological Assay , Haiti , Insecticide Resistance/physiology , Temperature
5.
J Am Mosq Control Assoc ; 28(4): 323-6, 2012 Dec.
Article in English | MEDLINE | ID: mdl-23393758

ABSTRACT

Insecticide resistance to organophosphates and carbamates can be the result of changes in acetylcholinesterase activity conferred by the ACE-1 mutation. Detection of this altered target site mutation is important in guiding informed decisions for resistance management. In this study we compared a competitive enzyme assay with a polymerase chain reaction assay utilizing a restriction enzyme. Both assays detected the ACE-1 mutation in Culex quinquefasciatus and agreement was 100%. The costs and benefits of each assay are presented.


Subject(s)
Acetylcholinesterase/metabolism , Cholinesterase Inhibitors/pharmacology , Culex/drug effects , Culex/enzymology , Insecticide Resistance , Insecticides/pharmacology , Acetylcholinesterase/genetics , Animals , Culex/genetics , Gene Expression Regulation, Enzymologic
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