Читать книгу Collins New Naturalist Library - M. Brian V. - Страница 20

Whereas prey provides mostly protein and oil and decomposes quickly, seeds are also rich in starch and they store well, provided germination can be prevented. Seed storage is a regular feature of ants that live in deserts where seed-producing, ephemeral plants may be quite common and the main source of food. Even in this country Myrmica, when it lives in acid grassland, collects the seeds of Potentilla erecta, but whether they are eaten or merely put in the nest is uncertain. Tetramorium caespitum on the other hand collects a great many seeds of grass and heather in late summer, both from the plant and after searching on the ground. Each seed is picked up and carried away individually; curiously enough, ling (Calluna vulgaris) is favoured, even though it has the smallest seed. Vast numbers are stored in galleries some 10–30 cm below the soil surface and are fed to the growing grubs in spring after a little preliminary mastication by the workers. They form a staple part of the diet and contribute substantially to the growth of the sexual brood in spring. The seeds never germinate during winter, this may simply be due to the low temperature or because they need light, for there is no evidence that the ants treat them in any way. Seed-eating myrmecines from semi-desert areas apparently take a great deal of trouble to keep their stores dry but this is certainly not the case with Tetramorium caespitum whose galleries are soaking wet for most of the year.

Although formicine ants do not collect seeds systematically records of this do exist. Lasius alienus collects the seeds of the dwarf gorse, Ulex minor; it only eats the oily caruncle, the rest is rejected undamaged and will germinate satisfactorily. The suggestion that the gorse is distributed in this way is reasonable. Lasius niger has been seen with viola and primula seeds; again, it only eats the stalk and the caruncle which contain oil and the rest presumably germinates after being thrown away by the ants. Wood ants, too, will take some kinds of seeds if these are put in their tracks; they, too, prefer the oily ones. The trapping results with Formica polyctena already mentioned show that a great many seeds are taken in along with other vegetable matter, such as buds and twigs; even pebbles coated with vegetable oil were picked up and carried away but soon rejected.