Effects of piperonyl butoxide synergism and cuticular thickening on the contact irritancy response of field Aedes aegypti (Diptera: Culicidae) to deltamethrin

Abstract

BACKGROUND: Exploiting indoor-resting mosquitoes' innate behavioral responses to commonly used insecticide is crucial in vector control programs. Indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) treated with pyrethroids have become widely used for controlling dengue fever vectors. The present study tested the effects of piperonyl butoxide (PBO) synergism and cuticular thickening on the contact irritancy response of field A. aegypti (Diptera: Culicidae) to deltamethrin in Taiwan and Thailand.RESULTS: The escape response of field mosquitoes treated with PBO was significantly elicited, with an escape percentage increase between 2-and 10-fold. In addition, the escape time was significantly lower in PBO-pretreated mosquitoes compared with field mosquitoes treated with deltamethrin alone. PBO-pretreated mosquitoes from seven out of 11 field strains exhibited a knockdown percentage of 11.23-54.91%, significantly higher than that of mosquitoes in corresponding strains treated with deltamethrin only. The Annan, Zhongxi, Sanmin, and North strains exhibited weak knockdown responses (≤3.75%). The mortality of PBO-pretreated field mosquitoes increased 2-to 75-fold compared with those treated with deltamethrin alone (mortality: 0-6.70%). Furthermore, the effect of cuticular thickness on the escape response of field mosquitoes was significant, that is, the escape response marginally increased inversely to cuticular thickness. By contrast, cuticular thickness was not significantly associated with knockdown or mortality percentage.CONCLUSION: Irritant behavior in mosquitoes was significantly elicited by PBO synergism. PBO incorporating deltamethrin IRS or LLINs may be effective for controlling dengue fever vectors.

Casearia tomentosa fruit extracts exposed larvicidal activity and morphological alterations in Culex quinquefasciatus and Aedes albopictus under in vitro and semi field conditions

“…measure about 3 μm in thickness which is more than cuticular thickness of mosquito species [ 51 ]. In the context of pesticide resistance, few studies have directly described modifications in the cuticle of the main arboviral vectors of the genus Aedes [ 52 , 53 ]. The survival of Chironomus circumdatus and Toxorhynchites splendens seems to be attributed to changes in cuticular thickness between target and non-target organisms.…”

Insecticide Resistance of Cimex lectularius L. Populations and the Performance of Selected Neonicotinoid-Pyrethroid Mixture Sprays and an Inorganic Dust

“…The modified cuticle may explain the delayed mortality. Increased cuticular thickness [ 27 , 69 ] was found in resistant bed bugs, therefore it may contribute to the delayed response of insect to insecticides [ 70 , 71 ]. Whether these mechanisms are responsible for the delayed response to CimeXa remains to be determined.…”

Cuticular profiling of insecticide resistantAedes aegypti

“…funestus possess distinct structural and biochemical alterations [18]. In contrast, very few studies have directly characterized cuticular alterations in the major arboviral vectors of the genus Aedes [37, 38]. One notable feature of this resistant phenotype is leg cuticular thickening.…”