Nanomaterials: A Review of Their Action and Application in Pest Management ... 115
mar Gowda ( 2013 ) reviewed the literature on the
status and scope of nanopartechnology in crop
protection.
Nanodispensers
Nanoparticle with good adsorption capacity
of pheromone molecules, slow and controlled
release of molecules during the entire period
of insect activity provide an opportunity to ex-
ploit such technology for pest management.
Many kinds of such materials were exploited as
pheromone dispensers, viz., filter paper, nylon
mesh, polymers, paraffin wax, zeolites, and glass
ampoules among others (Beroza et al. 1971 ; Sho-
rey et al. 1972 ; Bradley et al. 1995 ). The commer-
cially available dispensers are mainly made from
different kinds of polymers. Among several kinds
of silica-based porous glasses, porous vycor glass
(PVG) is a commercial transparent porous mate-
rial obtained by acid leaching of a phase-separat-
ed alkaline borosilicate glass (Aline Tiboni et al.
2008 ). The soluble borate phase is dissolved,
leaving an open porous structure of essentially
pure silica with interconnecting pores, a narrow
pore size distribution, and a pore volume of near-
ly 28 %. The pore surface contains slightly acidic
silanol groups. The nanometric pores in PVG
have been used to incorporate several compounds
(conducting polymers, oxides, semiconductors,
amorphous carbon, and carbon nanotubes), with
the purpose of obtaining novel functional nano-
composite materials. PVG was impregnated with
pheromones of Grapholita molesta (Lepidoptera:
Tortricidae) and Leucoptera coffeella (Lepidop-
tera: Lyonetiidae), the main pests of apple and
coffee plantations in Brazil, respectively (Aline
Tiboni et al. 2008 ). The release rate was depen-
dent on the interaction between the molecules of
the impregnated pheromone and the surface of
the PVG pores. A good performance of the po-
rous glass was observed, similar to that of rubber
septa commercially used as pheromone dispens-
ers (Aline Tiboni et al. 2008 ).
Nanogel is a synthetic polymer or biopolymer
which is chemically or physically cross linked.
Nanogels are usually in the tens to hundreds of
nanometers in diameter. The pores in nanogels
can be filled with small molecules or macromol-
ecules and properties such as swelling, degrada-
tion, and chemical functionality can be controlled
(Bencherif et al. 2009 ). A nanogel pheromone,
methyl eugenol is stable at ambient conditions
that results in slow release rate of pheromone.
Nanogelled pheromone brought about an ef-
fective management of Bactrocera dorsalis, a
prevalent harmful pest for a number of fruits in-
cluding guava (Bhagat et al. 2013 ).
Hydrogel is a network of polymer chains that
are hydrophilic, sometimes found as a colloidal
gel in which water is the dispersion medium. Hy-
drogels are highly absorbent natural or synthetic
polymers. Hydrogels also possess a degree of
flexibility similar to natural tissue, due to their
significant water content. These hydrogels can
be used in diverse areas of agriculture such as
dryland/rainfed agriculture, hi-tech horticul-
ture and floriculture, nursery raising in soil-less
media, soil reclamation, agroforestry, artificial
lawns and landscapes, terrace gardening, etc.
Heat-tolerant species of entomopathogenic nem-
atode, Steinernema thermophilum, incorporated
and immobilized into water insoluble superab-
sorbent hydrogel matrix, has been developed for
the first time by a simple method that comprises
swelling of the xerogel in appropriate volume of
aqueous suspension of the nematode. The formu-
lation obtained has improved shelf life ranging
from few hours to 36 months at storage tempera-
tures varying from 5 to 50 °C. The formulation
is not infected by any microorganism and hence
does not require any antimicrobial or antifungal
chemicals.Nanoparticles—A Revolution
in Future
Agricultural productivity enhancement by de-
velopment of slow-release formulation, with
efficient dosage insecticides, biopesticides, hor-
mones, and nanosensors for pest detection (Scri-
nis and Lyons 2007 ; Liu and Du 2004 ) has been
effected. Nanoparticles help to produce new
pesticides, insecticides, and insect repellants