Male-killing bacterium in fifth ladybird beetle, Coleomegilla maculata (Coleoptera: Coccinellidae)
1996
Hurst, G.D.D. | Hammarton, T.C. | Obrycki, J.J. | Majerus, T.M.O. | Walker, L.E. | Bertrand, D. | Majerus, M.E.N.
Inherited symbionts which selectively cause the death of male hosts are found widely across the Insecta. Previous studies have shown a single, but different micro-organism to be responsible for male-killing in each taxonomic group studied. We here produce evidence that within a group of insects, the Coccinellidae, there is more than one causal agent of male lethality. We report a novel observation of a male-killing trait in the species Coleomegilla maculata. Six of 26 crosses were found to produce a female-biased sex ratio associated with a low egg hatch-rate. The trait was matrilinearly inherited and was observed to be tetracycline-sensitive. However, tests which indicate the presence of a Rickettsia, previously found to cause male-killing in another member of the Coccinellidae, Adalia bipunctata, proved negative. We therefore conclude that the phenomenon of male-killing is multicausal, within, as well as between, taxonomic groups of the Insecta.
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