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2015:groups:g5:start

Group 5

Male-killing bacteria and egg cannibalism in ladybugs

Wiki site of the practical exercise of the IV Southern-Summer School on Mathematical Biology.

Here you will find the exercise assignment and the group's products.

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Introduction

Male-killers are maternally inherited bacteria that kill their male host early in the development resulting in female-biased sex ratios. Their transmission is strictly vertical, however not every egg laid by an infected mother carries the bacteria. Given their imperfect transmission, the absence of horizontal transfer and potential costs associated with the infection, additional mechanisms are necessary to explain male-killer persistence in natural populations.

Different species of ladybugs are known to host male-killing bacteria. Their larvae are voracious predators that eat mostly aphids but are also known to exhibit sibling cannibalism, a behavior that is affected by aphid density. Since infected male eggs do not develop into larvae, females from the same egg clutch may benefit from the consumption of these undeveloped eggs. This resource reallocation from brother to sister in infected clutches may be one of the mechanisms explaining male-killer persistence.

Larva and adult of the seven-spotted
ladybug near their most common prey: aphids (Image credit: t-mizo)

Assignment

Propose a model of male-killing infection that incorporates sibling cannibalism.

Suggested questions

  • Under what conditions can sibling cannibalism explain the persistence of male-killing bacteria?
  • How does the aphid population dynamics affect infection persistence?

References

  • Elnagdy, S., Majerus, M., & Lawson Handley, L.-J. (2011). The value of an egg: resource reallocation in ladybirds (Coleoptera: Coccinellidae) infected with male-killing bacteria. Journal of Evolutionary Biology 24, 2164–2172. link
  • Agarwala, B.K., & Dixon, A.F.G. (1992). Laboratory study of cannibalism and interspecific predation in ladybirds. Ecological Entomology 17, 303–309. link alternative link

Group results

2015/groups/g5/start.txt · Last modified: 2024/01/09 18:45 by 127.0.0.1