KRYSID (α-naphthylthiourea, C 10 H 7 NHCSNH 2 ) — the organic matter having high selective toxicity for rats and house mice.
For deratization To. it is offered in 1944 by I. Bashkov, A. A. Paseshnik and V. N. Polikarpov. To. — powder of gray or gray-brown color with a specific smell and bitterish taste. Solubility of pure drug in water at t ° 0 ° makes 16 mg on 100 ml; it is badly dissolved in ether and alcohol.
At storage in the dry room To. it is long does not lose poisonous properties.
Selective effect To. on rodents and low concentrations of poison in the poisoned baits do its use in deratization almost harmless to the person and animals. A lethal dose To. for rats at introduction with food of 4,5 mg, for house mice of 0,5 — 0,75 mg. Does not possess cumulative action. At repeated use resistance to drug at rats increases by 2,5 — 4 times and remains within 30 — 40 days. Rats eat the baits containing up to 1% To. Death of gray rats depending on a dose of drug occurs in 12 — 72 hours.
For extermination of rodents To. apply in the poisoned baits, and also apply on a water surface, or dust holes. For baits use the products willingly eaten by rodents (bread, meat, fish, vegetables, grain etc.).
For increase in efficiency of deratization top-dressing of rats not poisoned products chosen as a bait is reasonable preliminary (during 5 — 7 days). The poisoned baits are prepared by mechanical mixing of drug with foodstuff and use them right after production since at storage they quickly lose attractiveness for rodents. Baits can be prepared according to the following recipes. 1) Grain crumbs of 89 g, krysid 1 g, vegetable oil of 6 g, sugar of 4 g. In the beginning carefully mix drug with grain crumbs, then add oil and sugar. 2) Dough from rye or wheat flour of 94 g, krysid 1 g, vegetable oil of 5 g. Dough is cut pieces of 1 cm in size 3 . 3) Porridge millet, pearl-barley and other 99 g, krysid 1 g 4) the Beet, carrots, water-melon or melon crusts cut by pieces of 1 cm3, 99 g in size, krysid — 1 g 5) Grain of 94 — 97 g, vegetable oil of 2 g or 5 g, starch or flour paste of 2,5 g, krysid 1 g. The baits made with starch paste before use dry. Baits display in holes and on ways of movement of rodents. The consumption rate of a bait on 1 sq.m of the area at one-time focal processing makes 0,2 g, at systematic continuous processing of 0,1 g. After a priming of a hole close up alabaster, cement or hammer with a tin.
Efficiently for extermination of rats use of liquid baits is. In low flat and steady ware (baking sheets, frying pans, etc.) pour water and apply on it To. at the rate of 300 mg on 100 cm 2 water surface. Shaking ware, drug is evenly distributed on a surface. In winter time in not heated warehouse in drinking bowls fill the snow mixed with To., at the rate of 1 g of drug on 100 g of snow. Liquid water baits keep efficiency up to 7 days and more.
Dusting of holes is made by means of a rubber pear with the tip supplied with the device for dosing of powder or by means of other devices. Poison can be brought in holes also insertion of the tampons from tow pollinated To. Consumption rate To. on one hole of 1 — 2 g.
Continuous use To. shall not exceed 1 — 2 month. At mass production of baits it is necessary to use a respirator and rubber gloves.
I. S. Bezdenezhnykh, V. A. Arkayev