nucleation

LIT-1590: Changes in Endosymbiont Complexity Drive Host-Level Compensatory Adaptations in Cicadas

2 min read

Properties6
StatusActive — read in full 2026-10-27 (NOTE-1235) from the PubMed Central copy of the version of record (PMC6234865, CC BY 4.0); worth reading as the record's one documented case of a host compensating for its symbiont's changes at transmission: cicadas whose Hodgkinia has split into many lineages send more Hodgkinia cells to each egg, not more Sulcia, and every sampled egg carried every tracked lineage (THEORY-1106). Read it knowing that the rise in titre is significant for one species, Magicicada septendecim, of four compared, with five or six eggs each and no phylogenetic control; that the six-lineage species does not differ significantly from single-lineage ones; that lineage presence was tracked by one or two marker genes; and that the order of cause, splitting before titre, is inferred.
Version2
Tagsendosymbiosis, ecology, natural-sciences
Cited as “paper” byNOTE-1235 — Campbell et al. — Changes in endosymbiont complexity drive host-level compensatory adaptations in cicadas
Cited as “reported in” byCASE-177 — Hodgkinia in cicadas: one endosymbiont splitting into two to dozens of interdependent lineages, with near-complementary gene sets, idiosyncratic fragmentation in Magicicada, and hosts transmitting up to six times as many cells to keep every lineage
Cited as “source” byTHEORY-1106 — Campbell and colleagues report, from four cicada species with five or six eggs each, that Hodgkinia cells per egg range from about 4,900 in a species with one Hodgkinia lineage to about 30,000, some six times as many, in Magicicada septendecim, whose Hodgkinia has split into many interdependent lineages and the only species that differs significantly, while Sulcia numbers are not raised, the transmission route is the same, and every egg sampled carries every lineage tracked by marker genes; the authors take the raised titre as a host adaptation that compensates for the symbiont's fragmentation, and a cost of it, THEORY-1214 — Cicada hosts whose endosymbiont Hodgkinia has split into many interdependent lineages compensate by sending more Hodgkinia cells to each egg, with Sulcia numbers and the transmission route unchanged, so that every egg still receives every lineage; the raised titre is a host adaptation driven by the symbiont's fragmentation, and a cost of it

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Campbell, M. A., Łukasik, P., Meyer, M. C., Buckner, M., Simon, C., Veloso, C., Michalik, A. & McCutcheon, J. P. (2018). Changes in Endosymbiont Complexity Drive Host-Level Compensatory Adaptations in Cicadas. mBio 9(6): e02104-18. doi:10.1128/mBio.02104-18.

Key takeaways

From the reading, NOTE-1235.

  • The problem. With random transmission, the cells needed to give every egg every Hodgkinia lineage grow steeply as lineages multiply and grow uneven: over 500 per egg for one cell of each of T. chilensis’s six lineages, 4 to 5 times more at Magicicada’s complexity.
  • The host’s answer. Hodgkinia cells per egg range from 4,889 in a single-lineage cicada to 30,154 in M. septendecim; Sulcia stays between 2,572 and 5,643. Only M. septendecim differs significantly (THEORY-1106).
  • Transmission complete. Every sampled egg carried every tracked lineage, and eggs share their mother’s lineage proportions. Rare losses could escape detection, the authors say.
  • Same route. Under the light microscope, transmission looks the same in a three-lineage Tettigades and in Magicicada.
  • A possible feedback. Larger transmitted populations mean weaker bottlenecks, which the authors speculate could reduce host control and feed further splitting.

Why this is here

A2 listed “host compensation” (“selection to maintain collective functionality”, giving “transport, regulation, or metabolic rescue”) as a mechanism, and named no work for it. This is a documented case of the host compensating at the level of transmission, so it bears on reproductive cohesion (R) in QUESTION-277. The reading finds that the host maintains cohesion as the parts multiply, rather than raising it, and that the authors suspect the same change may weaken the host’s control. Registered for CASE-177.

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