Orchids comprise the largest family of flowering plants
with 25,000 to 35000 species belonging to 600-800 genera . They are prized for
their incredible diversity in the size, shape and color and attractiveness of
their flowers and high keeping qualities even upto 10 weeks. Most of theorchids have originated from tropical humid forests of Central and SouthAmerica, India, Sri Lanka, Burma, South China, Thailand, Malayasia,
Philippines, New Guinea and Australia. Brazilian Cattleya, Mexican Laelia and
Indian Cymbidium, Vanda and Dendrobium have played a major role in developing
present day beautiful hybrid orchids which numbers more than 200000. In the
international trade, among top ten cut flowers, orchids rank the sixth position
and among orchids Cymbidium ranks the first position and in floricultural crops
it accounts for 3% of the total cut flower production.
Insecticides are a class of pesticides used to
kill, harm, or repel different species of insects. They act in different ways
in organisms based on their active ingredients. For instance, corn plantations
commonly use insecticides that have organophosphates and carbamate as the
active ingredient, which acts on the enzyme acetylcholinesterase within an
insect nervous system. In many cases, these standard insecticide products are
being phased out for a new class of insecticide known as neonicotinoids, which use
nicotine as the active ingredient. Neonicotinoid compounds interact withnicotinic acetylcholine receptors (nAChR) of the central nervous systems ofinsects. Nicotine acts in an insect’s system in the same way that it acts in
the human body. However, neonicotinoids are more toxic for invertebrates than
they are to mammals, birds and other higher organisms.
Neonicotinoids became
popular because of their high water solubility, which makes their soil
application travel through the entire plant. Nowadays, neonicotinoids are one
of the most widely used class of insecticides for controlling sucking insects
and soil insects. In 2004, the worldwide annual usage of neonicotinoids was
approximately 11-15% of the total insecticides in the market. Differentgenerations of neonicotinoids have been created over time. They have the sameprinciple of action in the nervous system; however, the specific active
ingredients are different. The first generation of this pesticide class used
was 1-(6-chloro-1,3-thiazol- 5-ylmethyl)-1,3,5-oxadiazinan-4-ylidenene(nitro)amine,
known as Imidacloprid. It was first registered for use in the United States by
the United States Environmental Protection Agency in 1994.
Shrimps and Prawns of various kinds have certainly been a
source of protein for human consumptions from very early times. Within
historical times reference is made to prawn in ancient Chinese and Japanese
literature. Usage of the term ‘Prawn’ and ‘Shrimp’ are somewhat confusing. In
some western literature the term ‘Shrimp’ is applied for Penaeoidea and
Sergestoidea, but in the east these are called ‘Prawn’. Holthuis discussed the
contradiction but did not arrive at any conclusion. In the Prawn Symposium ofthe Indo-Pacific Fisheries Council held at Tokyo in 1955 it was decided thatthe word ‘Prawn’ should be applied to the Penaeids, Pandalids and Palemonids
while ‘Shrimp’ to the smaller species belonging to the other families. As such
in the present study the term ‘Prawn’ is used for all the species belonging to
family Penaeidae.
Among a variety of edible decapod crustaceans, prawns
contribute largely to the fishery wealth of many nations. Exploitation of prawnresource from the seas around each country is playing increasingly significantrole in furthering their national economy. In recent years, in spite of some
ecological hazards, the demand for prawns and prawn products has increased so
much that every country is making efforts to utilize hitherto unknown but
usable stocks and expansion of prawn fisheries and industries near coast line
is rightly being given the maximum encouragement in the development programme
of each nation. Therefore, the distribution of different species gradually
extending their range of distribution and newer species were recorded
throughout coastal region of each nation.
