Parasites and Enemies of Miners; Inquilines and Symbionts

Abstract

We mentioned earlier how the mine can be considered as a sort of “hot-house”; greater humidity and higher temperature create particularly favourable conditions for the larva feeding within, which is as a result in many cases able to reach maturity more rapidly than is possible with external feeders. If conditions in the mine are thus in every way favourable for the development of the miner, this applies also simultaneously to organisms which are working for its destruction and annihilation, among which parasites figure predominantly. It is true that the mining habit affords the larva greater protection against certain enemies which normally attack free-living larvae but not against all. Parasites, which have adapted themselves to leaf-miners and share living conditions in the mine with the producer, also experience favourable conditions which accelerate their development. Everyone who has spent time breeding miners knows that they are not free from parasites. Some groups of parasites, however, are completely excluded from this field. As far as our experience goes, parasitic Tachinidae (Larvaevoridae) never occur on larvae which pass their whole life in their mine The female of these flies is not able to insert its egg inside the mine channel, since it does not possess an ovipositor capable of penetrating into the mine cavity. All known cases of Tachinidae parasitising miners apply to temporary miners; as long as the larva lives inside its mine, it remains unmolested and it is attacked by the parasite only after having left the mine and is feeding on the surface of the leaf; here it is exposed to the ovipositing fly or may become infected by an egg on the leaf surface, as for instance with species of Phytomyzoptera on Gracilariidae, which after leaving their mine live under leaf rolls.

The online version of the original chapter can be found at http://dx.doi.org/10.1007/978-94-015-7196-8_40