Insecticides and Raticides

Insecticides and Raticides

Plants have been used to combat insects, rats and other vermin for many years in various parts of the world. Over 1200 species have been recorded as insecticides. Nicotine, obtained from tobacco, has long been familiar. Pyrethrum or insect flowers, which yield pyrethrum and derris and cube, which contain rotenone, are in greatest demand. Promising new sources however are continually being discovered. Red squill is the principal raticide.

Pyrethrum

Pyrethrum is non-inflammable, non- poisonous and leaves no oily residue. Three principal sources of the pyrethrum are recognized in the United States:-

1. Dalmatian insect flowers from Chrysanthemum Cinerariaefolium,

2. Persian insect flowers from C. Coccineum, and

3. Caucasian insect flowers from C. Marshallii.

The first of these is by far the most important. C. Cinerariaefolium is a slender, glaucous, pubescent perennial 18 to 30 inches in height with pinnate leaves and small daisy like flowers. It is a native of Dalmatia in Jugoslavia, where it has been cultivated for many years. prior to the second World War, Japan was the leading producer of pyrethrum flowers, and they constituted one of that country`s most valuable exports. Great care was exercised in gathering, drying and packing the crop.

During the last War, the army found it highly effective against flies, fleas, body lice and yellow fever and malarial mosquitoes. Pyrethrum bombs were standard equipment in malaria-infested areas. They contained the insecticide in a solvent under a pressure of 90 lb. per sq. inches. A mechanical release allowed the vapour to escape through a valve like a fog. A 2 sec. application permanently paralysed all insects. Pyrethrum ointment is used in the treatment of scabies.

Rotenone

The poisonous properties of rotenone – containing plants have been appreciated by native peoples for centuries. Rotenone is a colourless crystalline compound and related substances occur as solids in the dried roots. The content may be as high as 12 per cent. Rotenone is fifteen times more toxic than nicotine and twenty- five more than potassium Ferro-cyanide. It has little or no effect on humans or other warm blooded animals. There are two principal sources:-

1. Species of Derris, and

2. Species of Lonchocarpus.

Red Squill

It is obtained from the bulbs of the red variety of Urginea maritima, a native Mediterranean species which is cultivated in Algeria. Used as a raticide from ancient times, red squill has come into prominence within the last 20 years as a result of more active rat- control measures. The toxic substance, a glucoside, has little effect on other animals.

Save Nature Love Nature