scholarly journals Latitudinal trend in the reproductive mode of the pea aphid Acyrthosiphon pisum invading a wide climatic range

2020 ◽  
Vol 10 (15) ◽  
pp. 8289-8298
Author(s):  
Sebastián I. Martel ◽  
Carmen G. Ossa ◽  
Jean‐Christophe Simon ◽  
Christian C. Figueroa ◽  
Francisco Bozinovic
2020 ◽  
Author(s):  
Gaël Le Trionnaire ◽  
Sylvie Hudaverdian ◽  
Gautier Richard ◽  
Sylvie Tanguy ◽  
Florence Gleonnec ◽  
...  

AbstractAphids are major pests of most of the crops worldwide. Such a success is largely explained by the remarkable plasticity of their reproductive mode. They reproduce efficiently by parthenogenesis during spring and summer generating important damage on crops. At the end of the summer, asexual females perceive the photoperiod shortening and transduce this signal towards their embryos that change their reproductive fate to produce sexual individuals: males and oviparous females. After mating, those sexual oviparous females lay cold-resistant eggs. Previous studies based on large-scale transcriptomic analyses suggested that dopamine pathway might be a key player in the integration of decrease of the autumnal photoperiodic signal to promote the switch of embryonic germline fate. In this study, we investigated the role of dopamine pathway in the photoperiodic response of the pea aphid Acyrthosiphon pisum. We first analysed the level of expression of ten genes of this pathway in heads and embryos of aphids reared under long-days (asexual producers) or short-days (sexual producers). We then performed in situ hybridization experiments to localize in embryos the ddc and pale transcripts that are coding for two rate-limiting enzymes in dopamine synthesis. We then used pharmacological approaches to inject aphids with dopamine or a pale inhibitor to mimic short days and long days conditions and observe a putative effect on the distribution of their offspring. Altogether, our results indicate that photoperiod shortening is associated with a reduction in dopamine synthesis that might affect cuticle sclerotization process rather than neuro-transmission. Using CRISPR-Cas9 mutagenesis, we also tried to knock out ddc gene in eggs produced after the mating of sexual individuals. We could observe strong melanization defaults in ddc mutated eggs, which confidently mimicked drosophila phenotype. Nevertheless, such a lethal phenotype did not allow us to investigate the precise role of ddc in photoperiod shortening signal integration prior to the reproductive mode switch.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guang Wang ◽  
Jing-Jiang Zhou ◽  
Yan Li ◽  
Yuping Gou ◽  
Peter Quandahor ◽  
...  

AbstractTrehalose serves multifarious roles in growth and development of insects. In this study, we demonstrated that the high trehalose diet increased the glucose content, and high glucose diet increased the glucose content but decreased the trehalose content of Acyrthosiphon pisum. RNA interference (RNAi) of trehalose-6-phosphate synthase gene (ApTPS) decreased while RNAi of trehalase gene (ApTRE) increased the trehalose and glucose contents. In the electrical penetration graph experiment, RNAi of ApTPS increased the percentage of E2 waveform and decreased the percentage of F and G waveforms. The high trehalose and glucose diets increased the percentage of E2 waveform of A. pisum red biotype. The correlation between feeding behavior and sugar contents indicated that the percentage of E1 and E2 waveforms were increased but np, C, F and G waveforms were decreased in low trehalose and glucose contents. The percentage of np, E1 and E2 waveforms were reduced but C, F and G waveforms were elevated in high trehalose and glucose contents. The results suggest that the A. pisum with high trehalose and glucose contents spent less feeding time during non-probing phase and phloem feeding phase, but had an increased feeding time during probing phase, stylet work phase and xylem feeding phase.


1983 ◽  
Vol 115 (12) ◽  
pp. 1615-1619 ◽  
Author(s):  
William D. Hutchison ◽  
David B. Hogg

AbstractCornicle length measuremetns of Acyrthosiphon pisum (Harris) nymphs reared in the laboratory were instar-specific and unaffected by rearing temperature. A multimodal analysis of cornicle lengths of field-collected aphids clearly detected four distribution peaks (i.e., instars) in five different field populations, and there was generaaly little overlap between successive instar distributions. However, third and fourth instars in the spring field sample could not be separated accurately due to the shorter cornicle length of nymphs that developed from overwintered eggs. Cornicle length proved to be a useful criterion for separating virginoparous A. pisum instars in samples collected in southern Wisconsin.


2006 ◽  
Vol 72 (3) ◽  
pp. 1956-1965 ◽  
Author(s):  
Anne-Marie Grenier ◽  
Gabrielle Duport ◽  
Sylvie Pagès ◽  
Guy Condemine ◽  
Yvan Rahbé

ABSTRACT Dickeya dadantii (Erwinia chrysanthemi) is a phytopathogenic bacterium causing soft rot diseases on many crops. The sequencing of its genome identified four genes encoding homologues of the Cyt family of insecticidal toxins from Bacillus thuringiensis, which are not present in the close relative Pectobacterium carotovorum subsp. atrosepticum. The pathogenicity of D. dadantii was tested on the pea aphid Acyrthosiphon pisum, and the bacterium was shown to be highly virulent for this insect, either by septic injury or by oral infection. The lethal inoculum dose was calculated to be as low as 10 ingested bacterial cells. A D. dadantii mutant with the four cytotoxin genes deleted showed a reduced per os virulence for A. pisum, highlighting the potential role of at least one of these genes in pathogenicity. Since only one bacterial pathogen of aphids has been previously described (Erwinia aphidicola), other species from the same bacterial group were tested. The pathogenic trait for aphids was shown to be widespread, albeit variable, within the phytopathogens, with no link to phylogenetic positioning in the Enterobacteriaceae. Previously characterized gut symbionts from thrips (Erwinia/Pantoea group) were also highly pathogenic to the aphid, whereas the potent entomopathogen Photorhabdus luminescens was not. D. dadantii is not a generalist insect pathogen, since it has low pathogenicity for three other insect species (Drosophila melanogaster, Sitophilus oryzae, and Spodoptera littoralis). D. dadantii was one of the most virulent aphid pathogens in our screening, and it was active on most aphid instars, except for the first one, probably due to anatomical filtering. The observed difference in virulence toward apterous and winged aphids may have an ecological impact, and this deserves specific attention in future research.


Heredity ◽  
2002 ◽  
Vol 89 (5) ◽  
pp. 346-352 ◽  
Author(s):  
M C Caillaud ◽  
M Boutin ◽  
C Braendle ◽  
J-C Simon

2017 ◽  
Vol 83 (8) ◽  
Author(s):  
Matthew R. Doremus ◽  
Kerry M. Oliver

ABSTRACT Insects and other animals commonly form symbioses with heritable bacteria, which can exert large influences on host biology and ecology. The pea aphid, Acyrthosiphon pisum, is a model for studying effects of infection with heritable facultative symbionts (HFS), and each of its seven common HFS species has been reported to provide resistance to biotic or abiotic stresses. However, one common HFS, called X-type, rarely occurs as a single infection in field populations and instead typically superinfects individual aphids with Hamiltonella defensa, another HFS that protects aphids against attack by parasitic wasps. Using experimental aphid lines comprised of all possible infection combinations in a uniform aphid genotype, we investigated whether the most common strain of X-type provides any of the established benefits associated with aphid HFS as a single infection or superinfection with H. defensa. We found that X-type does not confer protection to any tested threats, including parasitoid wasps, fungal pathogens, or thermal stress. Instead, component fitness assays identified large costs associated with X-type infection, costs which were ameliorated in superinfected aphids. Together these findings suggest that X-type exploits the aphid/H. defensa mutualism and is maintained primarily as a superinfection by “hitchhiking” via the mutualistic benefits provided by another HFS. Exploitative symbionts potentially restrict the functions and distributions of mutualistic symbioses with effects that extend to other community members. IMPORTANCE Maternally transmitted bacterial symbionts are widespread and can have major impacts on the biology of arthropods, including insects of medical and agricultural importance. Given that host fitness and symbiont fitness are tightly linked, inherited symbionts can spread within host populations by providing beneficial services. Many insects, however, are frequently infected with multiple heritable symbiont species, providing potential alternative routes of symbiont maintenance. Here we show that a common pea aphid symbiont called X-type likely employs an exploitative strategy of hitchhiking off the benefits of a protective symbiont, Hamiltonella. Infection with X-type provides none of the benefits conferred by other aphid symbionts and instead results in large fitness costs, costs lessened by superinfection with Hamiltonella. These findings are corroborated by natural infections in field populations, where X-type is mostly found superinfecting aphids with Hamiltonella. Exploitative symbionts may be common in hosts with communities of heritable symbionts and serve to hasten the breakdown of mutualisms.


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