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1. Disruption of the sorghum circadian clock impacts sorghum-sugarcane aphid interaction dynamics and aphid feeding behavior

   https://doi.org/10.1016/j.stress.2024.100407  

   Shrestha, Kumar; Zogli, Prince; Pingault, Lise; Grover, Sajjan; Cardona, Juan Betancurt; Louis, Joe (March 2024, Plant Stress)
2. Dopamine mediates the pea aphid wing plasticity

   https://doi.org/10.1098/rsbl.2023.0024  

   Liu, Xiaomi; Brisson, Jennifer A. (May 2023, Biology Letters)

   Many organisms exhibit phenotypic plasticity, in which developmental processes result in different phenotypes depending on their environmental context. Here we focus on the molecular mechanisms underlying that environmental response. Pea aphids ( Acyrthosiphon pisum ) exhibit a wing dimorphism, in which pea aphid mothers produce winged or wingless daughters when exposed to a crowded or low-density environment, respectively. We investigated the role of dopamine in mediating this wing plasticity, motivated by a previous study that found higher dopamine titres in wingless- versus winged-producing aphid mothers. In this study, we found that manipulating dopamine levels in aphid mothers affected the numbers of winged offspring they produced. Specifically, asexual female adults injected with a dopamine agonist produced a lower percentage of winged offspring, while asexual females injected with a dopamine antagonist produced a higher percentage of winged offspring, matching expectations based on the titre difference. We also found that genes involved in dopamine synthesis, degradation and signalling were not differentially expressed between wingless- and winged-producing aphids. This result indicates that titre regulation possibly happens in a non-transcriptional manner or that sampling of additional timepoints or tissues is necessary. Overall, our work emphasizes that dopamine is an important component of how organisms process information about their environments. 

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3. Elevated temperatures alter an ant‐aphid mutualism

   https://doi.org/10.1111/eea.12839  

   Mooney, Emily; Davidson, Benjamin; Den Uyl, James; Mullins, Maria; Medina, Eva; Nguyen, Phuong; Owens, Janel (October 2019, Entomologia Experimentalis et Applicata)

   Abstract Ant‐hemipteran mutualisms are keystone interactions that can be variously affected by warming: these mutualisms can be strengthened or weakened, or the species can transition to new mutualist partners. We examined the effects of elevated temperatures on an ant‐aphid mutualism in the subalpine zone of the Rocky Mountains in Colorado, USA. In this system, inflorescences of the host plant,Ligusticum porteriCoult. & Rose (Apiaceae), are colonized by the ant‐tended aphidAphis asclepiadisFitch or less frequently by the non‐ant tended aphidCavariella aegopodii(Scopoli) (both Hemiptera: Aphididae). Using an 8‐year observational study, we tested for two key mechanisms by which ant‐hemipteran mutualisms may be altered by climate change: shifts in species identity and phenological mismatch. Whereas the aphid species colonizing the host plant is not changing in response to year‐to‐year variation in temperature, we found evidence that a phenological mismatch between ants and aphids could occur. In warmer years, colonization of host plant inflorescences by ants is decreased, whereas forA. asclepiadisaphids, host plant colonization is mostly responsive to date of snowmelt. We also experimentally establishedA. asclepiadiscolonies on replicate host plants at ambient and elevated temperatures. Ant abundance did not differ between aphid colonies at ambient vs. elevated temperatures, but ants were less likely to engage in tending behaviors on aphid colonies at elevated temperatures. Sugar composition of aphid honeydew was also altered by experimental warming. Despite reduced tending by ants, aphid colonies at elevated temperatures had fewer intraguild predators. Altogether, our results suggest that higher temperatures may disrupt this ant‐aphid mutualism through both phenological mismatch and by altering benefits exchanged in the interaction. 

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4. Male-Biased microRNA Discovery in the Pea Aphid

   https://doi.org/10.3390/insects12060533  

   Liu, Xiaomi; Culbert, Erica L.; Brisson, Jennifer A. (June 2021, Insects)

   Epigenetic mechanisms modulate gene expression levels during development, shaping how a single genome produces a diversity of phenotypes. Here, we begin to explore the epigenetic regulation of sexual dimorphism in pea aphids (Acyrthosiphon pisum) by focusing on microRNAs. Previous analyses of microRNAs in aphids have focused solely on females, so we performed deep sequencing of a sample containing early-stage males. We used this sample, plus samples from Genbank, to find 207 novel pea aphid microRNA coding loci. We localized microRNA loci to a chromosome-level assembly of the pea aphid genome and found that those on the X chromosome have lower overall expression compared to those on autosomes. We then identified a set of 19 putative male-biased microRNAs and found them enriched on the X chromosome. Finally, we performed protein-coding RNA-Seq of first instar female and male pea aphids to identify genes with lower expression in males. 10 of these genes were predicted targets of the 19 male-biased microRNAs. Our study provides the most complete set of microRNAs in the pea aphid to date and serves as foundational work for future studies on the epigenetic control of sexual dimorphism. 

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5. Snowmelt timing determines aphid abundance through multitrophic interactions

   https://doi.org/10.1016/j.actao.2020.103606  

   James, Den Uyl; Maria, Mullins; Shane, Heschel M.; Emily, Mooney (October 2020, Acta Oecologica)

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