8.1
Introduction
Stored grain pests cause significant damage to grains during storage, resulting in
quantitative and qualitative losses to the stored grains and making it unfit for
consumption. It attacks most of the cereals and pulses, millets, oilseeds, and
processed commodities stored in the public godowns and storage units of food
companies (Pourya et al. 2018). Stored product pests are majorly classified into
internal and external feeders based on the feeding behaviour. Internal feeders are also
called as primary pests which attack whole or unbroken grains, feed within the
grains, and cause damages inside the grain. The symptom of damage can be noticed
only after the emergence of the adults. External feeders are also known as secondary
pests which attack only damaged grains and milled products (Table 8.1). Practice of
chemical fumigation to the food grains results in residues in food materials and
resistance development in insects (Subramanyam 2018). Stored product pests
account to loss of 20–25% during 2010–2011 (Singh 2016). Controlling the stored
pest and preventing loss of the food grains are necessary to maintain sufficient buffer
stock (Nicolopoulou-Stamati et al. 2016). Chemicals in the form of fumigants are
used at present to manage the stored product insects. Considering the safety and
efficiency of using botanical insecticides, extensive studies on organic plants and
their phytochemical activity are being studied by many researchers for the development of botanical insecticides for stored product pest (D’Incao et al. 2013). This
chapter deals with the classification of phytochemicals, mode of action, extraction
and testing methods, analysis of phytochemicals and management of stored pests by
use of plant based chemicals.
8.2
Phytochemicals
Phytochemicals or phytoinsecticides are the chemicals derived from plant origin. It
originates from the Greek word phyto, meaning “plant” (Breslin 2017). Each
phytochemical has varying structure and performs different functions such as protection, growth acceleration, and reproduction in the plants (Huang et al. 2016).
Phytochemicals are found in fruits, vegetables, grains, pulses, nuts, seeds, and other
plant foods (Baxter et al. 1998). Since ancient times, medicinal plants and botanicals
were used to treat chronic diseases like cancer, diabetes, and coronary heart diseases
(Arnason et al. 2013). Certain plants contain phytochemicals (Table 8.2) which
possess insecticidal properties against pests (Table 8.3). Phytochemicals can be
Table 8.1 List of internal and external feeders damaging stored commodities
Internal
feeders
Rice weevil (Sitophilus oryzae), lesser grain borer (Rhyzopertha dominica),
pulse beetle (Callosobruchus chinensis), cigarette beetle (Lasioderma
serricorne), drug store beetle (Stegobium paniceum), angoumois grain moth
(Sitotroga cerealella), and copra beetle (Necrobia rufipes)
External
feeders
Red flour beetle (Tribolium castaneum), saw-toothed beetle (Oryzaephilus
surinamensis), and rice moth (Corcyra cephalonica)
172
L. Manickam et al.
Introduction
Stored grain pests cause significant damage to grains during storage, resulting in
quantitative and qualitative losses to the stored grains and making it unfit for
consumption. It attacks most of the cereals and pulses, millets, oilseeds, and
processed commodities stored in the public godowns and storage units of food
companies (Pourya et al. 2018). Stored product pests are majorly classified into
internal and external feeders based on the feeding behaviour. Internal feeders are also
called as primary pests which attack whole or unbroken grains, feed within the
grains, and cause damages inside the grain. The symptom of damage can be noticed
only after the emergence of the adults. External feeders are also known as secondary
pests which attack only damaged grains and milled products (Table 8.1). Practice of
chemical fumigation to the food grains results in residues in food materials and
resistance development in insects (Subramanyam 2018). Stored product pests
account to loss of 20–25% during 2010–2011 (Singh 2016). Controlling the stored
pest and preventing loss of the food grains are necessary to maintain sufficient buffer
stock (Nicolopoulou-Stamati et al. 2016). Chemicals in the form of fumigants are
used at present to manage the stored product insects. Considering the safety and
efficiency of using botanical insecticides, extensive studies on organic plants and
their phytochemical activity are being studied by many researchers for the development of botanical insecticides for stored product pest (D’Incao et al. 2013). This
chapter deals with the classification of phytochemicals, mode of action, extraction
and testing methods, analysis of phytochemicals and management of stored pests by
use of plant based chemicals.
8.2
Phytochemicals
Phytochemicals or phytoinsecticides are the chemicals derived from plant origin. It
originates from the Greek word phyto, meaning “plant” (Breslin 2017). Each
phytochemical has varying structure and performs different functions such as protection, growth acceleration, and reproduction in the plants (Huang et al. 2016).
Phytochemicals are found in fruits, vegetables, grains, pulses, nuts, seeds, and other
plant foods (Baxter et al. 1998). Since ancient times, medicinal plants and botanicals
were used to treat chronic diseases like cancer, diabetes, and coronary heart diseases
(Arnason et al. 2013). Certain plants contain phytochemicals (Table 8.2) which
possess insecticidal properties against pests (Table 8.3). Phytochemicals can be
Table 8.1 List of internal and external feeders damaging stored commodities
Internal
feeders
Rice weevil (Sitophilus oryzae), lesser grain borer (Rhyzopertha dominica),
pulse beetle (Callosobruchus chinensis), cigarette beetle (Lasioderma
serricorne), drug store beetle (Stegobium paniceum), angoumois grain moth
(Sitotroga cerealella), and copra beetle (Necrobia rufipes)
External
feeders
Red flour beetle (Tribolium castaneum), saw-toothed beetle (Oryzaephilus
surinamensis), and rice moth (Corcyra cephalonica)
172
L. Manickam et al.