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All Subjects: Temperature
Creators: Kalmouni, Joshua

Effect of Temperature on Insecticide Susceptibility in knockdown resistant Aedes aegypti

Description

Aedes aegypti are vectors for common arthropod-borne-diseases (arboviruses) such as Zika, yellow fever, dengue, and chikungunya, which are of significant public health concern. The management of vectors is critical to mitigating the incidence, reemergence, and expansion of these diseases. Vector control has been complicated by the emergence of insecticide resistance within vectors, which threatens the effectiveness of control efforts. Furthermore, vector management is also complicated by the interaction between insecticide susceptibility and abiotic factors, such as temperature. While it is well-documented that environmental factors affect insecticide susceptibility, it is poorly understood how insecticide resistant vectors with different genetic backgrounds respond to insecticides at different temperatures. This study aims to establish the relationship between deltamethrin susceptibility at varying temperatures across Ae. aegypti lines that differ in their susceptibility due to knockdown resistance (kdr) mechanism. This was done through exposures using the “WHO tube test method” using simulated climate environments (22°C, 27 °C, and 32 °C) on mosquitoes of varying resistance at 1016 and homozygous resistance at 1534. This experiment is still ongoing. This study found that IICC was the most resistant genotype, VVCC the least resistant, and VICC and intermediate. There was found to be no statistically significant relationship between temperature and insecticide susceptibility across kdr genotypes.

ContributorsAin, Joshua (Author) / Paaijmans, Krijn (Thesis director) / Huijben, Silvie (Committee member) / Jensen, Brook (Committee member) / Kalmouni, Joshua (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)

Created2023-05

Evaluating the Effects of Temperature on the Toxicity of Insecticides That Target Arbovirus Vectors in the Phoenix Metropolitan Area

Description

Despite its well-documented preference for much more humid climates, the yellow fever mosquito, or Aedes aegypti, has inhabited Arizona since 1951. Their presence is of great concern as they can transmit many deadly diseases, including yellow fever, chikungunya, Zika, and dengue fever, putting the residents of the Phoenix Metropolitan Area at risk. Maricopa County Vector Control has made an extensive effort to reduce this risk mainly through the act of fogging insecticides during the night in areas where mosquito numbers exceed a threshold. However, given the well-known temperature-toxicity relationships in insect species, fogging at night may be less or more effective —depending on the relationship— due to the colder temperatures at these times. Additionally, insecticide resistance testing has always been performed at temperatures not usually experienced during fogging, adding to the uncertainty on how useful those test outcomes are. This study took the first steps in determining the effects of temperature on the toxicity of a commonly used insecticide, deltamethrin, on Aedes aegypti by developing a dose response curve on a lab strain at a standard lab temperature of 25°C by performing a CDC bottle bioassay. The diagnostic dose was found to be 50 μg/mL and the lethal dose, 50% (LD50, the dose required to kill half of the test mosquitoes) was found to be 9 μg/mL. Future testing would need to be completed to compare the deltamethrin dose response curve developed in this study with deltamethrin dose response curves at various different temperatures.

ContributorsEl Sheikha, Mariam D (Co-author) / El Sheikha, Mariam (Co-author) / Paaijmans, Krijn (Thesis director) / Huijben, Silvie (Committee member) / Kalmouni, Joshua (Committee member) / Harrington Bioengineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)

Created2020-05