Multiple Mutations on the Second Acetylcholinesterase Gene Associated With Dimethoate Resistance in the Melon Aphid,Aphis gossypii(Hemiptera: Aphididae)

Abstract

The melon aphid, Aphis gossypii Glover (Hemiptera: Aphididae), is an important cosmopolitan and extremely polyphagous species capable of causing direct and indirect damage to various crops. Insecticide resistance in melon aphids is of particular concern. To determine the basis of resistance, organophosphate (OP)-resistant strains of A. gossypii were obtained by continuous selection with dimethoate in the laboratory, and resistance mechanisms were investigated along with susceptible strains. Three resistant strains LKR-1, LKR-2, and LKR-3 exhibiting 270-, 243-, and 210-fold resistance obtained after 30 generations of selection with dimethoate, respectively, were utilized in this study. The role of acetylcholinesterase (AChE), a target enzyme for OPs and carbamates (CMs), was investigated. AChE enzyme assay revealed that there was no significant change in the activities of AChE in resistant and susceptible strains. However, AChE inhibitory assay showed that 50% of the enzyme activity in resistant strains was inhibited at significantly higher concentration of dimethoate (131.87, 158.65, and 99.29 µmolL(−1)) as compared with susceptible strains (1.75 and 2.01 µmolL(−1)), indicating AChE insensitivity owing to altered AChE. Molecular diagnostic tool polymerase chain reaction-restriction fragment length polymorphism revealed the existence of two consistent non-synonymous point mutations, single-nucleotide polymorphism, viz., A302S (equivalent to A201 in Torpedo californica Ayres) and S431F (equivalent to F331 in T. californica), in the AChE gene Ace2 of resistant strains. Further, cloning and sequencing of a partial fragment of Ace2 (897 bp) gene from susceptible and resistant strains revealed an additional novel mutation G221A in resistant strains, LKR-1 and LKR-2. Susceptible Ace2 genes shared 99.6 and 98.9% identity at the nucleic acid and amino acid levels with resistant ones, respectively. Functional analysis of these point mutations was assessed by in silico docking studies using the modeled wild-type and naturally mutated AChE2. Computational analysis showed that the conformational changes in AChE2 active site due to structural gene substitutions (A302S, S431F, and G221A) significantly reduced the level of ligand (OP-dimethoate, omethoate, and CM-pirimicarb) binding, suggesting that they are potentially associated with resistance development. These results unambiguously suggested that multiple mutations located in the enzyme active site are responsible for AChE insensitivity to dimethoate and are likely the molecular basis for dimethoate resistance in these selected field populations of A. gossypii.

Evaluation of sublethal and transgenerational effects of sulfoxaflor on Aphis gossypii via life table parameters and 16S rRNA sequencing

“…To date, A. gossypii has developed resistance to various pesticides, including dimethoates, pyrethroids, neonicotinoids. [2][3][4] The integrated pest management of A. gossypii poses a serious challenge, which has prompted development of new pest control methods and insecticides.…”

Overexpression of UDP‐glycosyltransferase potentially involved in insecticide resistance in Aphis gossypii Glover collected from Bt cotton fields in China

“…It infects plants directly through feeding and indirectly through honeydew contamination and transmission of viral pathogens . Through direct and/or indirect contact with various chemical insecticides, field populations of A. gossypii have developed resistance to different types of insecticides, including organophosphates, carbamates, pyrethroids, and neonicotinoids . As for other insects, multiple resistant mechanisms have been reported to potentially contribute to insecticide resistance in A. gossypii , including enhanced detoxification by UGTs.…”

“…20 Through direct and/or indirect contact with various chemical insecticides, field populations of A. gossypii have developed resistance to different types of insecticides, including organophosphates, carbamates, pyrethroids, and neonicotinoids. [21][22][23] As for other insects, multiple resistant mechanisms have been reported to potentially contribute to insecticide resistance in A. gossypii, including enhanced detoxification by UGTs. Thirteen UGTs were up-regulated approximately 2.0-fold in laboratory-selected thiamethoxam resistant A. gossypii, in which the suppression of UGT348A2, UGT344B4, and/or UGT344J2 significantly decreased the insensitivity of resistant aphids to thiamethoxam.…”

Resistance Mechanisms to Chlorpyrifos and Propoxur in German Cockroach Blattella Germanica (L.) (Blattodea: Ectobiidae)

“…В ряде работ резистентность к ФОС (в том числе к хлорпирифосу) и к карбаматам, связывают с мутациями АХЭ, что делает невозможным связывание инсектицида и АХ. Показано это на примере высокорезистентных популяций вредителей сельского хозяйства -цикадках, тлях, белокрылках [32,33]. У рыжего таракана устойчивая АХЭ встречается достаточно редко -частоты резистентных аллелей генов нечувствительной к ФОС и карбаматам АХЭ составляют 0,03-0,08 [14].…”