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Updated: Sep 27, 2026
Mass-Rearing and Molecular Studies in Tortricidae Pest Insects
Published on: March 25, 2022
Space and the persistence of male-killing endosymbionts in insect populations
Maria A C Groenenboom1, Paulien Hogeweg
1Theoretical Biology and Bioinformatics, University of Utrecht, Padualaan 8, 3584 CH Utrecht, The Netherlands. m.a.c.groenenboom@bio.uu.nl
Abstract:
Male-killing bacteria are bacteria that are transmitted vertically through the females of their insect hosts. They can distort the sex ratio of their hosts by killing infected male offspring. In nature, male-killing endosymbionts (male killers) often have a 100% efficient vertical transmission, and multiple male-killing bacteria infecting a single population are observed. We use different model formalisms to study these observations. In mean-field models a male killer with perfect transmission drives the host population to extinction, and coexistence between multiple male killers within one population is impossible; however, in spatially explicit models, both phenomena are readily observed. We show how the spatial pattern formation underlies these results. In the case of high transmission efficiencies, waves with a high density of male killers alternate with waves of mainly wild-type hosts. The male killers cause local extinction, but this creates an opportunity for uninfected hosts to re-invade these areas. Spatial pattern formation also creates an opportunity for two male killers to coexist within one population: different strains create spatial regions that are qualitatively different; these areas then serve as different niches, making coexistence possible.
Insights
Male-killing bacteria distort insect sex ratios. Spatial models reveal how these bacteria can coexist and prevent host extinction through pattern formation, unlike simpler models.
Area of Science:
- Microbiology
- Ecology
- Evolutionary Biology
Background:
- Male-killing bacteria are vertically transmitted endosymbionts that infect insect hosts.
- These bacteria can significantly alter host sex ratios by eliminating male offspring.
- High vertical transmission rates and the presence of multiple male-killer strains within a population are observed in nature.
Purpose of the Study:
- To investigate the population dynamics of male-killing bacteria using mathematical models.
- To understand how spatial structure influences the persistence and coexistence of male-killing bacteria.
- To explain the observed phenomena of host population survival and multi-strain coexistence.
Main Methods:
- Utilized mean-field models to represent bacterial-host interactions.
- Employed spatially explicit models to incorporate spatial dynamics.
- Analyzed pattern formation in bacterial and host populations.
Main Results:
- Mean-field models predicted host population extinction and precluded coexistence of multiple male killers.
- Spatially explicit models demonstrated that spatial pattern formation allows for host population survival.
- Spatial dynamics facilitate the coexistence of different male-killer strains by creating distinct ecological niches.
Conclusions:
- Spatial structure is crucial for understanding the ecological dynamics of male-killing bacteria.
- Pattern formation in host-parasite interactions can prevent extinction and promote biodiversity.
- Spatially explicit models provide a more realistic framework for studying endosymbiont transmission and its evolutionary consequences.
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