Application of poisoned arsenic bait

We examine experiences of applying pellets of arsenic-coated wheat bran and pesticide sprays. The arsenic bran was applied by ground crews, while the pesticides were delivered both on the ground and from the air. The high costs involved and persistence of the pesticides in the environment were some of the disadvantages that have seldom been discussed. First, the baits were applied by hand over large areas where the swarms had landed or bands of hoppers were present, which made it extremely labor intensive. Second, the materials were too bulky to transport in countries without established road infrastructure. Third, the locusts were not always attracted to the wheat brans, and therefore those that survived were able to form future generations. Fourth, the method is expensive compared to aerial spraying of swarms (see below). Fifth, the arsenic baits posed dangers to livestock in the local areas.11'

In inaccessible areas, the anti-locust teams were often forced to use camels to haul the sacks containing the baits.118 In both Somaliland and the Reserved Area of Ogaden in Ethiopia, the Somalis were opposed to the use of arsenic baits against locusts. This became a political issue when the Somali nomads accused the government of poisoning the environment with the intention of killing their livestock. According to Jama Mohamed,119 resistance by the Somali pastoralists intensified in 1945 when poisoned bait killed their livestock, which the Somalis used ‘as incontrovertible evidence of government policy to reduce livestock by any means necessary.’ For fear of violent reaction by the nomads, the anti-locust teams were given military escorts, and even so, anti-locust activities in several districts were stopped.120 In other areas, despite the opposition, the anti-locust teams continued to lay wet bran against mature locusts and dry wheat bran against hoppers, with some success. In the Red Sea Hills campaigns,121 3,000 tons of bait were used during the summer and winter campaigns in 1950. The baiting was applied in the morning before the hoppers began marching. We now present aerial application of spray methods for locust control.

Application of aerial sprays

The 1940s and 1950s were periods of experimentation, using the donated military vehicles and planes. The aircrafts were medium to heavy Second World War bombers that had been converted into transport planes and fitted with pesticide sprays. This availability of former military planes increased the capacity for surveillance of locusts over wide areas. A search belt of about 300 km was covered to locate the locusts in flight, while the locations of those that had landed were communicated by radio to the ground teams. The airborne insect radar could pick up even low densities of locusts in flight, and their ‘volume-density [was] measured and variations in density with height.’122

The ability to synchronize surveillance between countries was essential to the success of the anti-locust campaigns. Most importantly, using military planes for spraying the swarms while in the air and on the ground, the organizations involved in desert locust control developed the capacity to work across international borders. This method was designed to kill large populations of locusts before they landed and damaged crops and grazing lands. The method was least constrained by the rugged topography that was inaccessible to ground crews. In addition, aerial surveillance provided a bird’s eye view of the behavior of the swarms in flight in relation to wind direction, thus allowing the sprays to be applied with greater precision.125 Due to the promising results, the British Government organized a coordinated series of attacks between 1942 and 1947, while the locusts were still in Indo-Pakistan, Arabia and Somaliland. The operations were coord- inated with military precision and cost £1 million per annum.124

The method of aerial spraying also contributed to scientific experimentation, in terms of appropriate concentrations of pesticides, patterns and frequencies of applications, and killing rates. The choice of pesticides was based on their effectiveness and safety.125 Three types of pesticides were used: a 20 percent concentration of DNC (dinitrocresol) in oil, against adults (either settled or in flight) and dieldrin emulsion against hoppers.126 Application of dieldrin12, at an average of 2.5 gallonsha 1 produced a kill rate of 100 percent; and the application of 50 gallons of 11 percent gamma BHC (benzene hexachloride) in oil killed about 60 to 80 tons of locusts.128

Aerial sprays allowed coverage of topographies that would otherwise be difficult to reach.129 About 50,000 gallons of pesticide would spray roughly

50,000 acres.10 The insecticide is persistent in the environment and would continue to kill any hoppers that eventually began to feed on the vegetation.131 Regardless of the effectiveness of these pesticides, opinions on their use were divided. On one hand, there were those who demanded that the pesticides should be banned, and stocks destroyed; while on the other hand, there were those who advocated continuing application thereof in remote areas, under supervision. Moreover, researching and producing alternative pesticides was not conducted, due to the costs involved.132

The results of the spraying campaigns were reported to the Anti-Locust Research Centre in London to evaluate the reliability of the insecticides. D.L. Gunn13 listed a number of factors to be considered when assessing the effectiveness of insecticides, including dosage, persistence in the environment under field conditions and, most importantly, safety for those applying the insecticides. Contrary to claims of the insecticides being ‘safe,’ their long-term impact on other biological organisms, as well as on livestock and wildlife, was not evaluated. The pesticide residues are known to be present in milk and meat products.134 Indeed, Gunn13’ even claims that the safety of popular insecticides such as dieldrin was exaggerated as part of the propaganda used by the Desert Locust Control Units.136

There were also other problems with aerial sprays. The first was transportation of large quantities of BHC dust on poor roads over long distances, to places where the chemicals were loaded into the aerial spray tanks of Beaver fixed-wing aircraft. A further problem was the long time it took to load the chemicals into the spray tanks. Such delays often allowed the swarms to escape. The most serious setbacks to the aerial spray method was that convectional air currents could suddenly change course, causing the ‘clouds of the insecticides’ to be carried away from the target; this could be avoided if the sprays were applied a few hours after sunrise.137 Considering that the swarms could travel at more than 50 km per hour, a Beaver aircraft had to load up from a single base and spray the airborne swarms in four sorties before sunset.138 The effectiveness of aerial spraying and the types of pesticides continued to be investigated as part of experimental research on locust control.

 
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