Pheromones for cotton and rice pests

Simple, low cost and non-polluting techniques have been developed for protecting cotton against three species of bollworm, and for protecting rice against stem-borer. Plastic strips, impregnated with highly specific sex-attractant pheromones are distributed within crops. The chemicals, which mimic the pheromones released by female insects, are slowly released and so saturate the atmosphere within the crops that males become confused and fail to locate and mate with the females. In trials with cotton in Pakistan, plastic twist-ties were used to release pheromones . Twist-ties consist of a thin wire embedded in plashc: they are used widely to fasten plastic rubbish bags and are cheap to produce. For pest control, the plastic is impregnated with the chemical - in this case, three pheromones specific to pink, spiny and spotted bollworm. The special twist-ties are attached to the cotton plants before the pests become established; they provide protection for the critical period of fruit formation. Immediately before the trial, infestation was so severe that farmers had to apply pyrethroid every 12 days during fruit formation but with the use of twist-ties the number of insecticide sprays could be reduced to two The twist-tie used in cotton was developed by the Shin-Etsu Chemical Company of Japan. A similar approach has been developed by a British company, Biological Control Systems, for ricestem borer. BCS produce squares of black plastic polymer 2 x 2 cm and 1 mm thick, also impregnated with pheromone. These are placed in split canes, which are distributed in rice fields. Trials in Spain showed that treatment with pheromones released in this way protected crops for more than 100 days and gave results comparable to rice fields treated with conventional pesticide. The advantage of CTOp protection withpheromones is that they are not toxic to living organisms and their effect is specific to target species, leaving Beneficial insects unharmed. However, one problem is that the intense ultra-violet light in tropical sunshine can inactivate pheromones. Many insect pheromones occur as isomers, only one of which is active, and uftraviolet light can induce molecules to between the two isomeric forms. For more details, contact: Shin Etsu Chemical Company Fine Chemicals Dept. 6-1 Ohtemachi 2 Chome Chiyoda-ku Tokyo JAPAN or Biological Control Systems -Treforest Industrial Estate Pontypridd -Mid Glamorgan CF37 5SU UKSimple, low cost and non-polluting techniques have been developed for protecting cotton against three species of bollworm, and for protecting rice against stem-borer. Plastic strips, impregnated with highly specific sex-attractant pheromones are..