Mar 13, 2017

Crop Protection WCRC Croprotection-Asia WCRC1
Introduction                                                                Back to Table of contents

The pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) is a major world-wide pest of cotton.  Once the eggs have hatched and the larvae have entered into the bolls it is difficult to control using conventional insecticides.

The spiny bollworm, Earias insulana (Boisduval) (Lepidoptera: Noctuidae), is largely confined to the near and middle Eastern areas of the world, including the Mediterranean; the spotted bollworm, Earias vittella (Fabricius) (Lepidoptera: Noctuidae) is found further East, particularly in the Indian sub-Continent and is a more sporadic and localised pest.  However, in some years it is capable of causing serious reductions in cotton yield.  Unlike the pink bollworm, which as its name implies primarily attacks the cotton bolls, the spiny and spotted bollworms damage all stages of the crop, the pin-squares, flowers and bolls, and can also act as a stem borer in young cotton plants.



There are now two pheromone formulations available with which it is possible to control the three major bollworm pests of cotton in Pakistan.  Trials have demonstrated clearly that larval infestations by these three species can be reduced and yields of seed cotton increased by a single early season application of either of the formulations containing both pheromones.  Numbers of insecticide applications to control secondary pests can also be reduced.  An important consequence of the reduction in the levels of pesticide applied is the increased numbers of beneficial insects present in the pheromone treated areas which contributes to reduced levels of attack by potentially serious pests such as H. armigera and B. tabaci.

Although the materials and techniques are now available, pheromonal control of the Earias spp. is not an economically viable option at the present time due to the current cost of Earias pheromone.  It is hoped that new and cheaper synthetic routes will be developed, as has happened with other pheromones, which will reduce their cost and lead to their eventual commercial use in cotton pest management.  However, acceptance by farmers and decision makers in Pakistan of the benefits of using pheromones to control of  P. gossypiella is expanding and current commercial evaluation of P. gossypiella pheromone formulations is expected to lead to wider availability and increased use.

The use of slow-release pheromone formulations to control cotton bollworm pests will  also provide the opportunity to reduce current levels of pesticide applied to control the cotton pest complex in Pakistan.  If their use is integrated into the cotton pest management recommendations, they will form an important element of a future Insecticide Resistance Management (IRM) strategy.  This could be of considerable benefit in a region where pesticide resistance in cotton pests is an increasing threat to sustainable cotton production.

Although both the pheromone formulations tested can only be applied by hand, this  makes them particularly suitable for use in Pakistan and other developing countries, where agriculture in general and cotton cultivation in particular is labour intensive and a work-force is available with which to apply the formulations.

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