there was an inverse correlation between palatability of litter and its total polyhydric
phenol content and positive correlation with the amount of soluble carbohydrates. In
tropics, Tian et al. (1993) reported that earthworm populations were negatively
correlated with the ratio of lignin to nitrogen of the plant residue. According to
Muys et al. (1992), earthworm biomass diminished under an oak tree (Quercus
palustris) due to poor quality of the oak litter and acidification of the soil by oak
leaves. High contents of polyphenol, flavonoid, and lignin in the litter of 3- and
10-years-old rubber plantations, through their effects on food intake probably
resulted in low biomass values of earthworms in those age group of the plantation
(Chaudhuri et al. 2013).
11.5 Influence of Environmental Factors on Survival
and Growth of Earthworms
Growth of earthworm species, cocoon production, cocoon development, and hatching all are critically influenced by the environmental conditions.
11.5.1 Temperature
Within the temperature range of 25 and 31
C growth, reproduction and cocoon
production occurs. If these limits are greatly exceeded, worms may move to a
suitable zone in the wastes or leave it or may even die. Edwards (1988) studied
the life cycle and optimal condition for survival growth of E. fetida, E. eugeniae, and
P. excavatus. According to Edwards (1988), optimum temperature for E fetida,
E. eugeniae, and P. excavatus were 25
C, and the latter two species died below
9
C and above 30
C when kept for longer period. In fact, temperature beyond
optimum level acts as cues for neurosecretory activity thus affecting cocoon production (Olive and Clark 1978). Temperature affects the incubation period of
cocoons. With the increase in room temperature, incubation period is increased in
P. elongata and D. nepalensis and decreased in P. excavatus and Dichogaster
modiglianii (Bhattacharjee and Chaudhuri 2002). Reinecke et al. (1992) reported
that temperature higher than 25
C decreased the mean incubation period in the
epigeic worms, P. excavatus and in E. eugeniae and E. fetida. The optimum
temperature in which the cocoon of an earthworm species hatch is the threshold
temperature, which according to Holmstrup et al. (1991) is an adaptation to the
particular habitat condition in which the species live. In general, the threshold
temperature during hatching is lower than the temperature during the incubation
period of the cocoon of earthworm species. Thus, room temperature (
C) during
hatching in P. excavatus (29.52 Æ 0.25), L. mauritii (29.60 Æ 0.49), D. modiglianii
(29.88 Æ 0.31), D. nepalensis (29.56 Æ 0.60), and Eutyphoeus gammiei (28.0) was
11 Growth and Reproductive Biology of Earthworms in Organic Waste Breakdown. . .
189
phenol content and positive correlation with the amount of soluble carbohydrates. In
tropics, Tian et al. (1993) reported that earthworm populations were negatively
correlated with the ratio of lignin to nitrogen of the plant residue. According to
Muys et al. (1992), earthworm biomass diminished under an oak tree (Quercus
palustris) due to poor quality of the oak litter and acidification of the soil by oak
leaves. High contents of polyphenol, flavonoid, and lignin in the litter of 3- and
10-years-old rubber plantations, through their effects on food intake probably
resulted in low biomass values of earthworms in those age group of the plantation
(Chaudhuri et al. 2013).
11.5 Influence of Environmental Factors on Survival
and Growth of Earthworms
Growth of earthworm species, cocoon production, cocoon development, and hatching all are critically influenced by the environmental conditions.
11.5.1 Temperature
Within the temperature range of 25 and 31
C growth, reproduction and cocoon
production occurs. If these limits are greatly exceeded, worms may move to a
suitable zone in the wastes or leave it or may even die. Edwards (1988) studied
the life cycle and optimal condition for survival growth of E. fetida, E. eugeniae, and
P. excavatus. According to Edwards (1988), optimum temperature for E fetida,
E. eugeniae, and P. excavatus were 25
C, and the latter two species died below
9
C and above 30
C when kept for longer period. In fact, temperature beyond
optimum level acts as cues for neurosecretory activity thus affecting cocoon production (Olive and Clark 1978). Temperature affects the incubation period of
cocoons. With the increase in room temperature, incubation period is increased in
P. elongata and D. nepalensis and decreased in P. excavatus and Dichogaster
modiglianii (Bhattacharjee and Chaudhuri 2002). Reinecke et al. (1992) reported
that temperature higher than 25
C decreased the mean incubation period in the
epigeic worms, P. excavatus and in E. eugeniae and E. fetida. The optimum
temperature in which the cocoon of an earthworm species hatch is the threshold
temperature, which according to Holmstrup et al. (1991) is an adaptation to the
particular habitat condition in which the species live. In general, the threshold
temperature during hatching is lower than the temperature during the incubation
period of the cocoon of earthworm species. Thus, room temperature (
C) during
hatching in P. excavatus (29.52 Æ 0.25), L. mauritii (29.60 Æ 0.49), D. modiglianii
(29.88 Æ 0.31), D. nepalensis (29.56 Æ 0.60), and Eutyphoeus gammiei (28.0) was
11 Growth and Reproductive Biology of Earthworms in Organic Waste Breakdown. . .
189