Saturday, January 26, 2008

Plant fungus affects sex ratios in parasitic wasp

The study, recently published in the Proceedings of the Royal Society B, focused on the fungus (Podosphaera plantaginis), the plant (Plantago lanceolata), the checkerspot caterpillar (Melitaea cinxia) and the parasitoid wasp (Cotesia melitaearum) that share habitat in Ă…land, Finland.
The fungal endophyte alters leaf chemistry in the host plant. This slows the growth rate in Melitaea cinxia caterpillars that feed of the plant. The parasitoid wasp lays its eggs on the caterpillar; like other parasitoids, the wasp larvae gradually consume the still-living host. When the female wasp lays her eggs on caterpillars feeding on Podosphaera plantaginis plants, she ends up producing twice as many female as male offspring. A skewed sex ratio improves the success of these wasps in the fragmented habitat in which they live.

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