Parasitic wasp hypodermic needle sniffs out larvae to lay eggs.

It takes a special kind of insect to pollinate an inside-out flower, which is exactly what the wasps that pollinate figs do. Crawling inside the firm swelling lined with microscopic flowers that will eventually ripen into a fleshy fig, tiny fig wasps pollinate the flowers within while laying their own eggs. However, the fig wasps’ robust nursery is not entirely secure. Renee Borges from the Indian Institute of Science explains that some parasitic wasp species seek fig wasp larvae to nurture their own young, and these and other parasitic species that lay their eggs directly in the fruit are equipped with a sharp hypodermic needle (ovipositor) that drills into the hard fig before the wasp injects its eggs. However, it is not sufficient for these parasitic interlopers to inject their eggs at random. Parasitic wasps that target fig wasp larvae must locate the developing youngsters within the flesh of the fruit. Knowing that pockets of gas could indicate the presence of fig wasp larvae developing within ripening figs, Borges and her student Pratibha Yadav wondered whether the tip of the parasitic wasp’s egg injector could be guided by odour sensors that could literally sniff out potential host larvae within.