Behavioral Action of Deltamethrin and Cypermethrin in Pyrethroid-Resistant Aedes aegypti (Diptera: Culicidae): Implications for Control Strategies in Thailand.

Contact irritant (locomotor excitation) and noncontact spatial repellent avoidance behavior to deltamethrin and cypermethrin at dosages 0.025, 0.05, and 0.

Field-collected permethrin-resistant Aedes aegypti from central Thailand contain point mutations in the domain IIS6 of the sodium channel gene (KDR).

One of the mechanisms responsible for pyrethroid resistance in mosquitoes is mutations in domain IIS6 of voltage-gated sodium channel gene (kdr). Aedes aegypti larvae were collected from the central provinces of Thailand (Bangkok, Prachin Buri and Ratchaburi) and colonized until they became adults. Partial fragment of kdr of permethrin-resistant mosquitoes were amplified by RT-PCR and sequenced.

Detection of insecticides resistance status in Culex quinquefasciatus and Aedes aegypti to four major groups of insecticides.

The resistance to various insecticides from 4 major groups (organochlorine, organophosphate, carbamate and pyrethroid) was investigated in a field strain of Culex quinquefasciatus from Baan Suan community, Nonthaburi province, Thailand by using a standard World Health Organization susceptibility test. The Baan Suan strain was completely resistant to DDT and highly resistant to deltamethrin, permethrin, fenitrothion and propoxur but this strain was still found to be highly susceptible to malathion. This strain displayed high resistance to cypermethrin since the result revealed that the resistance ratio of the 50% lethal concentration value (RR50) between the field and the laboratory strains (NIH strain) was 16.

Biochemical detection of pyrethroid resistance mechanism in Aedes aegypti in Ratchaburi province, Thailand.

The emergence of insecticide resistance in mosquito vectors was an important issue to be considered as one of factors influencing the success of vector control. The early detection of resistance could help the health personnel to plan and select appropriate alternative control measures or insecticide for effective control. Therefore biochemical assay of enzymes in mosquito was conducted to detect the emergence of insecticide resistance and to define the machanisms involved in pyrethroid resistance.

Insecticide susceptibility and selection for resistance in a population of Aedes aegypti from Ratchaburi province, Thailand.

The insecticide susceptibility of Aedes aegypti larvae and adults from four areas of Ratchaburi Province, Thailand was investigated using World Health Organization standard procedures. The larvae of Ae. aegypti in all areas were found to be susceptible to temephos.

Temephos resistance in two forms of Aedes aegypti and its significance for the resistance mechanism.

Aedes aegypti, at the larval stage, has been subjected to the temephos selection in laboratory. The level of temephos resistance was detected in a microplate by biochemical assay using WHO bioassay technique. The major enzyme-based resistance mechanisms involved in temephos resistance include elevated nonspecific esterase, oxidase and insensitive acetylcholinesterase.

Potential development of temephos resistance in Aedes aegypti related to its mechanism and susceptibility to dengue virus.

The addition of temephos to water containers as a larvicide against Aedes aegypti was commonly used as a part of DHF control programs. The widespread, or long-term, application of insecticides can lead to the development of mosquito resistance to the insecticides through selection pressure. This presents a problem for disease control.