Agriculture Reference
In-Depth Information
The geophilid chilopods and the ilulid diplopods are the only groups which possess
adaptations for digging. Even so, they prefer soils which facilitate their movement such
as those of sandy texture or with extended networks of fissures and earthworm galleries.
Growth is often slow and myriapods may live for several years. In temperate climate
French forests, two major groups may be distinguished: species with short developmen-
tal cycles (6 months to one year) (such as the Polydesmida and Craspedosomatida) and
those with long cycles (2-4 years), for example, Iulida and Glomerida (Fairhurst, 1974;
Geoffroy, 1981; David, 1982).
Diplopods have a thick cuticle encrusted with calcium carbonate which protects them
from both water excess and desiccation. This adaptation to widely changing moisture
conditions has made them a constant feature of forest leaf litter layers all over the world.
Chilopods which have a thinner cuticle are more sensitive to water stresses.
Diplopods are often favoured by high soil calcium concentrations (Fairhurst, 1974).
They feed on decomposing wood or leaf materials and they grow better on partially-
weathered material and have a marked preference for litters with high Ca and low
polyphenol contents. As a result, in temperate deciduous forests, birch (
Betula alba
) and
ash (
Fraxinus excelsior
) litters are more favourable than beech (
Fagus sylvatica
) or oak
(
Quercus robur
) litters (Raw, 1967; Marcuzzi, 1970; Edwards, 1974). Development is
slow and may last for three years in tropical species (Lévieux and Aouti, 1978; Aouti,
1977) and 5-7 years in colder areas (Vachon, 1947; Blower and Miller, 1977).
Chilopoda include large Scolopendrida or Lithobiomorpha which hunt in the litter,
and tiny Geophilidae which go deeper into the soil, following galleries and crevices.
Diptera
Dipteran larvae (Insecta) are an extremely diverse group both taxonomically and
nutritionally. They may occasionally become a predominant component of the soil fauna
and may effect a spectacular reduction of litter mass (see
e.g.,
Healey and Russell-Smith,
1971; Altmuller, 1979; Deleporte, 1987). In a French temperate-climate forest, the soil
and litter community comprised 29 different families (Mollon, 1982). Dipteran larvae
are predominantly saprophagous but also include predaceous, necrophagous,
xylophagous, coprophagous, micro-and macro-phytophagous species (Brauns, 1954).
The larvae live mostly in litter and some of them have developed remarkable resistance
to drought (Delettre and Baillot, 1977) although soil texture and water regime may
influence their distributions (Trehen, 1971; Blanchart
et al.,
1987).
Coleoptera
The adults and larvae of the insect order Coleoptera are also a consistent feature of
soil animal communities. They are diverse taxonomically and differ widely in size, and in the
ecological roles they fulfil in soils and litters. Most of them live in the litter. They are
saprophagous, phytophagous or predators. Two groups may have considerable local impor-
tance: Scarabaeinae larvae (dung-beetles) which are crucial in burying cow-dung in grass-
lands used for cattle grazing (see,
e.g.,
Bal, 1982; Brussaard and Hijdra, 1986; Lumaret and
Kirk, 1987) and Melolonthinae whose larvae may occasionally be abundant in grasslands and
affect crop production by feeding on living roots (
e.g.,
Villalobos and Lavelle 1990). Other
important families in soils and litter are the super family Staphylinoidea, families
