20.1 Introduction
India is an agrarian economy and the demand for higher agricultural growth is
arising with an increasing population. The rising demand for food remains an
unaccomplished target due to the inadequate knowledge about agricultural practices
and services. In order to ensure higher agricultural growth, the need for use of
pesticides has emerged. The usage of pesticides to sustain higher agricultural
production affects the non-target organisms in soil and water (Abdullah et al.
1997; Nath et al. 1997; Suh et al. 2000; Reinecke and Reinecke 2007; Yasmin and
D’Souza 2010) as well as decreases their growth rate and reproductive power
(Takada et al. 2000; Yasmin and D’Souza 2010). The population of beneficial soil
microorganisms declines due to heavy treatment with an increased amount of
pesticide residue levels in the soil. The widespread lack of awareness among the
Indian farmers regarding the recommended application dose of pesticide, method of
application and unscientific disposal of packaging material has resulted in the
application of multiple doses of pesticides into the fields causing environmental
and health degradation. The indiscriminate use of pesticides to increase the productivity of crops leads to toxic hazards to beneficial soil organisms like earthworms.
Earthworms are one of the non-target organisms of soil biota which play a crucial
role in improving soil fertility and structure. Earthworms improve the soil organic
matter physically and chemically by mixing leaf litter with soil and thereby facilitating the formation and stabilization of soil aggregates. Exposure of earthworms to
pesticides leads to bioaccumulation of pesticides in them, which causes serious
damages to higher trophic levels compared to the effects caused in the earthworms
itself (Darling and Thomas 2005; Hobbelen et al. 2006; Van Gestel et al. 2011).
Therefore, earthworms are used as bio-indicators of soil contamination to provide
safety limit values for pesticides application (Suthar et al. 2008; Lourenço et al.
2011).
Methyl parathion (MP) 2% dust is a commonly used pesticide in India for paddy
and wheat crops. According to the World Health Organization (WHO), MP 2% dust
is an extremely hazardous Class 1A pesticide belonging to the class of the organophosphate group. Like other organophosphates, MP is also a cholinesterase inhibitor
(Suthar 2014). India is considered as the second largest consumer of organophosphate insecticide (about 40–45% of the total consumption of pesticide) (Abhilash
and Singh 2009). MP 2% dust is focused mainly on controlling chewing and sucking
insects in a varied range of crops, vegetables and cotton crops (Suthar 2014). In an
experiment by Suthar (2014), MP 2% dust was exposed to different species of
tropical earthworms which caused less injury to the epigeic earthworms which
dwelt on the surface but the damage caused to the endogeic earthworm was lethal.
After the review of scientific literature, it is realized that the effect of MP 2% dust at
lethal and sub-lethal doses on epigeic earthworm Eisenia fetida has not been well
documented. In this context, a series of toxicity tests were conducted on epigeic
earthworm Eisenia fetida using MP 2% dust (active ingredient, a.i.) to validate
whether MP 2% dust is toxic or non-toxic to non-target organisms. The aims of
352
A. Nath and S. Hait
India is an agrarian economy and the demand for higher agricultural growth is
arising with an increasing population. The rising demand for food remains an
unaccomplished target due to the inadequate knowledge about agricultural practices
and services. In order to ensure higher agricultural growth, the need for use of
pesticides has emerged. The usage of pesticides to sustain higher agricultural
production affects the non-target organisms in soil and water (Abdullah et al.
1997; Nath et al. 1997; Suh et al. 2000; Reinecke and Reinecke 2007; Yasmin and
D’Souza 2010) as well as decreases their growth rate and reproductive power
(Takada et al. 2000; Yasmin and D’Souza 2010). The population of beneficial soil
microorganisms declines due to heavy treatment with an increased amount of
pesticide residue levels in the soil. The widespread lack of awareness among the
Indian farmers regarding the recommended application dose of pesticide, method of
application and unscientific disposal of packaging material has resulted in the
application of multiple doses of pesticides into the fields causing environmental
and health degradation. The indiscriminate use of pesticides to increase the productivity of crops leads to toxic hazards to beneficial soil organisms like earthworms.
Earthworms are one of the non-target organisms of soil biota which play a crucial
role in improving soil fertility and structure. Earthworms improve the soil organic
matter physically and chemically by mixing leaf litter with soil and thereby facilitating the formation and stabilization of soil aggregates. Exposure of earthworms to
pesticides leads to bioaccumulation of pesticides in them, which causes serious
damages to higher trophic levels compared to the effects caused in the earthworms
itself (Darling and Thomas 2005; Hobbelen et al. 2006; Van Gestel et al. 2011).
Therefore, earthworms are used as bio-indicators of soil contamination to provide
safety limit values for pesticides application (Suthar et al. 2008; Lourenço et al.
2011).
Methyl parathion (MP) 2% dust is a commonly used pesticide in India for paddy
and wheat crops. According to the World Health Organization (WHO), MP 2% dust
is an extremely hazardous Class 1A pesticide belonging to the class of the organophosphate group. Like other organophosphates, MP is also a cholinesterase inhibitor
(Suthar 2014). India is considered as the second largest consumer of organophosphate insecticide (about 40–45% of the total consumption of pesticide) (Abhilash
and Singh 2009). MP 2% dust is focused mainly on controlling chewing and sucking
insects in a varied range of crops, vegetables and cotton crops (Suthar 2014). In an
experiment by Suthar (2014), MP 2% dust was exposed to different species of
tropical earthworms which caused less injury to the epigeic earthworms which
dwelt on the surface but the damage caused to the endogeic earthworm was lethal.
After the review of scientific literature, it is realized that the effect of MP 2% dust at
lethal and sub-lethal doses on epigeic earthworm Eisenia fetida has not been well
documented. In this context, a series of toxicity tests were conducted on epigeic
earthworm Eisenia fetida using MP 2% dust (active ingredient, a.i.) to validate
whether MP 2% dust is toxic or non-toxic to non-target organisms. The aims of
352
A. Nath and S. Hait