Preventive control strategy
All countries affected by desert locust generally adopt a preventive control strategy for the management of desert locust in order to reduce the frequency, duration and intensity of plagues.
This strategy consists of regular surveys to provide early warning and contingency planning to allow early and effective response before the situation becomes out of control. LWO (comprising of all field units) undertakes regular surveys in the scheduled desert area of Rajasthan and Gujarat to monitor the presence of desert locust and ecological conditions. During the survey, an assessment is made to determine, if the locust numbers have crossed the economic threshold level (ETL) which is 10,000 adults/ha. and 5-6 hoppers/bush that may require control.
The constant watch and surveys are undertaken in desert areas with green vegetation (surface) and about two weeks after receiving the rain. These surveys are done regularly during the entire year, but most importantly from May to November when desert locust activity is considered at its peak due to congenial breeding conditions. This coincides with the monsoon season in Rajasthan and Gujarat. During this time, the frequency of surveys is doubled from May to November as compared to December to April.
The surveys are undertaken from sunrise to mid-day and for a few hours in the evening before sunset in the temperature range of 20–38°C. Whenever and wherever the population of desert locust is found exceeding the economical threshold level, immediate control measures are pressed into operation. Control operations are not conducted when locust numbers are low, isolated and scattered because this would not be effective and it would be harmful to the environment. In addition to LWO, concerned state authorities are also requested to keep constant watch over the development of locust activities and inform to the nearest Locust Circle office, if any development is seen and further action is required.
India has witnessed several locust plagues and upsurges since 1812 to 1997. More recently, there have been several control campaigns that were conducted. Since December 2011, no locust upsurges have taken place.