scholarly journals Selective sweeps in a nutshell: the genomic footprint of rapid insecticide resistance evolution in the almond agroecosystem

Author(s):  
Bernarda Calla ◽  
Mark Demkovich ◽  
Joel P Siegel ◽  
João Paulo Gomes Viana ◽  
Kim K O Walden ◽  
...  

Abstract Among the most familiar forms of human-driven evolution on ecological time scales is the rapid acquisition of resistance to pesticides by insects. Since the widespread adoption of synthetic organic insecticides in the mid-twentieth century, over 500 arthropod species have evolved resistance to at least one insecticide. Efforts to determine the genetic bases of insecticide resistance have historically focused on individual loci, but the availability of genomic tools has facilitated the screening of genome-wide characteristics. We re-sequenced three contemporary populations of the navel orangeworm (Amyelois transitella), the principal pest of almond orchards in California, differing in bifenthrin resistance status to examine insecticide-induced changes in the population genomic landscape of this species. We detected an exceptionally large region with virtually no polymorphisms, extending to up to 1.3 Mb in the resistant population. This selective sweep includes genes associated with pyrethroid and DDT resistance, including a cytochrome P450 gene cluster and the gene encoding the voltage-gated sodium channel para. Moreover, the sequence along the sweep is nearly identical in the genome assembled from a population founded in 1966, suggesting that the foundation for insecticide resistance may date back a half-century, when California’s Central Valley experienced massive area-wide applications of DDT for pest control.

2019 ◽  
Author(s):  
Bernarda Calla ◽  
Mark Demkovich ◽  
Joel P. Siegel ◽  
João Paulo Gomes Viana ◽  
Kim K.O. Walden ◽  
...  

AbstractRelatively few genome-wide population studies of field-acquired insecticide resistance have been carried out on agricultural pests. Recently acquired bifenthrin resistance in a population of the navel orangeworm (Amyelois transitella), the main insect pest of almond orchards in California, provided an opportunity to examine the short- and long-term effects of heavy insecticide usage in the population genomic landscape of this species. We re-sequenced the genomes of three contemporary A. transitella natural populations differing in bifenthrin resistance status and characterized their population genetics parameters, in the process we detected an exceptionally large selective sweep in all populations. This sweep has virtually no polymorphisms and extends up to 1.3 Mb (spanning 43 genes) in the resistant population. We analyzed the possible causes of this unusually strong population genetic signature, and found genes in the sweep that are associated with DDT and pyrethroid resistance including a cluster of cytochrome P450 coding genes and the gene coding for the small conductance sodium channel “para”. Moreover, we found that the sequence along the sweep is nearly identical in the genome assembled from a strain founded in 1966, suggesting that the underpinning for insecticide resistance may have been laid a half-century ago when the California Central Valley experienced massive area-wide applications of DDT for pest control. Our findings are consistent with a scenario whereby insecticide resistance in this species evolved as a stacking of selective pressures that started decades ago and that effectively reduced variation in a region of the genome containing several genes associated with resistance to insecticides with a shared target site and mechanism of action.


Genome ◽  
1993 ◽  
Vol 36 (1) ◽  
pp. 1-7 ◽  
Author(s):  
R. A. Morton

The impact of insecticide resistance is well documented. It includes the toxic effects of pesticides on the environment and the cost of the increased amounts of insecticides required to effectively control resistant insects. Resistance evolves by the selection of genes that confer tolerance to insecticides. Several resistance genes have been identified and cloned in Drosophila, including genes for mutant target molecules and genes that increase insecticide degradation. Drosophila is a useful system to understand the evolution of quantitative traits in general as well as the population genetics of insecticide resistance. Through it, we may hope to understand the relationship between discrete genetic change and continuously varying characters. In addition, molecular genetic techniques developed using Drosophila can eventually be transferred to other insects in order to help control pest populations.Key words: insecticide resistance, evolution of tolerance, selection of resistant genes, molecular genetics, Drosophila.


2019 ◽  
Author(s):  
Yu-Peng Chen ◽  
Gu-Qian Wang ◽  
Ting Yu ◽  
Xiao-Yan Peng ◽  
Tao Li ◽  
...  

The oriental fruit fly Bactrocera dorsalis (Hendel) is a worldwide pest leading to crop production. The management of B. dorsalis is becoming more and more difficult because of the emerging insecticide resistance. Searching for new and effective methods in managing this pest has become an urgent task. Here, we explored the relationship between pigmentation and insecticide resistance through conducting studies on 5 strains of B. dorsalis (CK, CZ, CB, LC and LX) with various traits of pigmentation and insecticide resistance. Strain CK was a wild strain with brown pupae coloration while strain CZ was a beta-cypermethrin-resistant strain with pupae coloration was brown. Strain CB was a pigmentation mutation strain with white pupae coloration. Strain LC was the female of pigmentation sex genetic strain whose pupae coloration was white. Strain LX was the male of pigmentation sex genetic strain whose pupae coloration was brown. Efficacy tests were employed to evaluate the resistance performance of the 5 trains, transcriptome sequencing and gene quantifications were used to explore the potential genes in both pigmentation and detoxification pathway. The brief of results were as follow: Results of efficacy tests of the 5 strains with beta-cypermethrin, abamectin and trichlorfon respectively showed that resistances to these three insecticide of strains LX and LC were very low. The corrective mortalities of strains LX and LC in 128 ug/ml of abamectin were 49.48±3.01%, 59.06±1.89% respectively while that of strain CK was 11.80%±1.37. The corrective mortality of strain CZ were lowest in all concentrations level of all test reagent. The resistance of strain CK was similar to CB. Transcriptomic analysis showed that 24 genes and 165 genes were associated with pigmentation and detoxification. Gene expression pattern of strain CK was similar to strain CB while these two strains were different to strains LC and LX, and the gene expression pattern of strain CZ was more similar to strains LC and LX. Results of gene quantifications in B. dorsalis pupae showed that the relative expressions of yellow gene MK529913, DDC gene MK515141, laccase2 gene MK515143 and PO gene MK515140 in brown pupae (CK, CZ, LX) were significantly higher than those in white pupae (CB, LC) while the relative expressions of AANAT gene MK515144 in white pupae were significantly higher than those in yellow pupae. In summary, analyses of gene quantifications and efficacy tests indicated that high expressions of P450 gene, AANAT gene might contribute to resistances of adults of B. dorsalis to beta-cypermethrin and a bamectin; high expression of yellow gene might contribute to resistances of adults which emergenced from brown pupae to beta-cypermethrin and abamectin; high expressions of yellow genes, laccase2 gene, PO gene and DDC gene might contribute to the resistance of B. dorsalis to trichlorfon.


2020 ◽  
Vol 57 (4) ◽  
pp. 1176-1183
Author(s):  
Fan Yang ◽  
Samuel Schildhauer ◽  
Sarah A Billeter ◽  
Melissa Hardstone Yoshimizu ◽  
Robert Payne ◽  
...  

Abstract Insecticide resistance in Aedes aegypti mosquitoes poses a major threat to public health worldwide. There are two primary biological mechanisms that can lead to insecticide resistance, target site and metabolic resistance, both of which confer resistance to specific classes of insecticides. Due to the limited number of chemical compounds available for mosquito control, it is important to determine current enzymatic profiles among mosquito populations. This study assessed resistance profiles for three metabolic pathways, α-esterases, β-esterases, and mixed-function oxidases (MFOs), as well as insensitivity of the acetylcholinesterase (iAChE) enzyme in the presence of propoxur, among Ae. aegypti from the Central Valley and southern California. All field-collected Ae. aegypti demonstrated elevated MFOs and iAChE activity, indicating potential development of pyrethroid and organophosphate resistance, respectively. Although regional variations were found among α-esterase and β-esterase activity, levels were generally elevated, further suggesting additional mechanisms for developing organophosphate resistance. Furthermore, mosquito samples from southern California exhibited a higher expression level to all three metabolic enzymes and iAChE activity in comparison to mosquitoes from the central region. These results could help guide future mosquito control efforts, directing the effective use of insecticides while limiting the spread of resistance.


2016 ◽  
Vol 283 (1843) ◽  
pp. 20161429 ◽  
Author(s):  
M. F. Hawkes ◽  
C. E. Gamble ◽  
E. C. R. Turner ◽  
M. R. Carey ◽  
N. Wedell ◽  
...  

The BA allele of the Drosophila cytochrome P450 gene Cyp6g1 confers resistance to a range of insecticides. It is also subject to intralocus sexual conflict when introgressed into the Canton-S background, whose collection predates the widespread use of insecticides. In this genetic background, the allele confers a pleiotropic fitness benefit to females but a cost to males, and exhibits little sexual dimorphism in conferred insecticide resistance. It is unclear whether these sexually antagonistic effects also exist in current populations that have naturally evolved with insecticides, where genetic modifiers that offset male costs might be expected to evolve. Here, we explore these issues using Drosophila melanogaster caught recently from an Australian population in which the BA allele naturally segregates. While we find increased fecundity in insecticide-resistant BA females and no consistent evidence of fitness costs in males, experimental evolution indicates balancing selection at the locus. We suggest that this apparent discrepancy may be due to reduced investment in reproduction in resistant males. Our results at the population level are consistent with previous work, and suggest that individual-level fitness assays do not always capture sexually antagonistic fitness effects that emerge in a population context.


BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
V. A. Ingham ◽  
F. Brown ◽  
H. Ranson

Abstract Background Malaria control is heavily reliant on the use of insecticides that target and kill the adult female Anopheline vector. The intensive use of insecticides of the pyrethroid class has led to widespread resistance in mosquito populations. The intensity of pyrethroid resistance in some settings in Africa means mosquitoes can contact bednets treated with this insecticide class multiple times with minimal mortality effects. Furthermore, both ageing and diel cycle have been shown to have large impacts on the resistance phenotype. Together, these traits may affect other aspects of vector biology controlling the vectorial capacity or fitness of the mosquito. Results Here we show that sublethal exposure of a highly resistant Anopheles coluzzii population originally from Burkina Faso to the pyrethroid deltamethrin results in large and sustained changes to transcript expression. We identify five clear patterns in the data showing changes to transcripts relating to: DNA repair, respiration, translation, behaviour and oxioreductase processes. Further, we highlight differential regulation of transcripts from detoxification families previously linked with insecticide resistance, in addition to clear down-regulation of the oxidative phosphorylation pathway both indicative of changes in metabolism post-exposure. Finally, we show that both ageing and diel cycle have major effects on known insecticide resistance related transcripts. Conclusion Sub-lethal pyrethroid exposure, ageing and the diel cycle results in large-scale changes in the transcriptome of the major malaria vector Anopheles coluzzii. Our data strongly supports further phenotypic studies on how transcriptional changes such as reduced expression of the oxidative phosphorylation pathway or pyrethroid induced changes to redox state might impact key mosquito traits, such as vectorial capacity and life history traits.


2021 ◽  
Author(s):  
Nicholas E Karagas ◽  
Kai Li Tan ◽  
Hugo J. Bellen ◽  
Kartik Venkatachalam ◽  
Ching-On Wong

Mutations in the gene encoding VAPB (vesicle-associated membrane protein B) cause a familial form of Amyotrophic Lateral Sclerosis (ALS). Expression of an ALS-related variant of vapb (vapbP58S) in Drosophila motor neurons results in morphological changes at the larval neuromuscular junction (NMJ) characterized by the appearance of fewer, but larger, presynaptic boutons. Although diminished microtubule stability is known to underlie these morphological changes, a mechanism for the loss of presynaptic microtubules has been lacking. Here, we demonstrate the suppression of vapbP58S-induced changes in NMJ morphology by either the loss of ER Ca2+ release channels or the inhibition Ca2+/calmodulin (CaM)-activated kinase II (CaMKII). These data suggest a model in which decreased stability of presynaptic microtubules at vapbP58S NMJs result from hyperactivation of CaMKII due to elevated cytosolic [Ca2+]. We attribute the Ca2+ dyshomeostasis to delayed extrusion of cytosolic Ca2+ stemming from a paucity of activity-induced mitochondrial ATP production coupled with elevated rates of ATP consumption. Taken together, our data point to bioenergetic dysfunction as the root cause for the synaptic defects in vapbP58S-expressing Drosophila motor neurons.


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