Fairyfly - Ecology

Ecology

All known fairyflies are parasitoids of eggs of other insects. These are commonly eggs which are laid in concealed locations, like in plant tissues or underground. They do not seem to be species-specific when it comes to choosing hosts. Some species are known to parasitize insects from several families of a single order. Their most common hosts are insects belonging to the order Hemiptera (true bugs), especially Auchenorrhyncha (leafhoppers, cicadas, and allies) and Coccoidea (scale insects), but this might be because these groups are simply better studied. Other important host orders include Coleoptera (beetles), Diptera (true flies), Odonata (dragonflies and allies), Psocoptera (booklice and allies), and Thysanoptera (thrips). Hosts are known definitely for only a quarter of all known genera.

Fairyflies include the smallest known insect, Dicopomorpha echmepterygis from Costa Rica, which have males that are only 0.139 mm (0.0055 in) long. They do not have wings or eyes, their mouths are mere holes, and their antennae are simply spherical blobs. The ends of their legs have been modified into suction cups for clutching at females long enough to fertilize them. They are so small, their entire bodies are smaller than a single-celled Paramecium. Four male individuals, lined up end-to-end, would just about encompass the width of a period at the end of a typical printed sentence. The females of the species, however, are typical fairyflies, and are much larger.

Fairyflies have unique nervous systems resulting from the necessity to conserve space. They have one of the smallest brains, containing only 7,400 neurons. They are also the first (and only) known animals which have functioning neurons without nuclei.

The neurons develop during pupation with functional nuclei and manufacture enough proteins to last through the short lifespans of the adults. Before emerging as an adult, the nuclei are destroyed, allowing the fairyfly to conserve space by making the neurons smaller. Even without nuclei (which contain the DNA, essential for manufacturing proteins to repair damage in living cells), the neurons can survive because the proteins manufactured as a pupa are sufficient.