FAO's desert locust specialists have travelled from the Sahara to the Indo-Pakistan desert arming local organizations in the fight against crop-eating locust swarms. Keith Cressman, FAO Locust Survey Officer, opens his diary after giving a recent training course to officers of India's Locust Warning Organization in the western state of Rajasthan
Hot on the trail of India's desert locusts
Standing guard is India's Locust Warning Organization, which maintains a permanent presence monitoring movements along the Indo-Pakistan border. It's a strategic task, for further east stands the country's rich croplands. The organization's last serious offensive was in 1993 when planes sprayed insecticides on swarms arriving from the Arabian Peninsula in late June.
Our work this afternoon, in heat close to 40 degrees Centigrade, was to help the 17 officers assess infestations that could lead to plagues and mark those that require control operations. But finding them is the difficult part. However, there are some telltale signs such as circling birds and the presence of certain types of vegetation locusts like to feed on.
Making estimates of locust numbers is even more difficult. There are various ways: we suggested just walking some distance -- at least 300 m but this depends on the extent of suitable vegetation at the site. Estimate the width that you might be disturbing locusts and count the number that fly up -- don't double count! It's best to report the number of locusts per distance walked, or you can calculate the number of locusts per sample area -- in this case the area equals distance walked multiplied by the width disturbed. In other words, just report what you see!
Yet demonstrating its use was far more difficult than I had anticipated. Most of the officers, who were from different parts of Rajasthan, had never handled electronic equipment and were unaware of the functions. Other obstacles must be overcome before officers will begin to use it much like a pencil or pen. Although they are cheap and getting cheaper (US$199), they are still considered expensive when compared to a locust officer's salary. So there is some fear of losing it or having it stolen.
Days 3 and 4
Detecting breeding areas is critical. One way is to determine soil moisture, vital for breeding. Dig into the ground at about 10 to15 cm, grab a handful of soil, and squeeze it. If the soil remains clumped together, it is probably moist enough for locusts to lay eggs -- it will also be a darker colour. This works well with sandy soil and sandy-clay -- both types preferred by locusts for laying.
It was now time to survey our own work and ask the officers what they thought of our presentation. I had learned a lot and really enjoyed the trip. Again we headed back into the desert. But this time, it was to marvel at the sun setting against a ridge of high sand dunes.
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