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4 Planned investigations
4.1 Tests with IGRs
The investigations with IGRs can be regarded as essentially complete. This is reinforced by the fact that the results of a large-scale trial conducted in Northeast Mauritania (Dorow 1995) are now available. Here, barriers 1000 m in width were set up from aircraft over a test area totalling 4 million ha. The vast majority of the hopper bands located in the test area died. Having said that, different mortality rates were recorded (57 to over 90%) as a function of the type and density of, and degree of coverage by, vegetation, and as a function of hopper band stages. In this connection, further investigation of the dose-effect relationships is required.
4.2 Investigations with botanicals
As regards the botanicals, extensive tests are still needed. These relate to appropriate formulations, dosages and application. With regard to the last point, tests on reduction of fitness with respect to mobility and food uptake are especially necessary, and further investigations are also needed into the flight capacity of adults treated with sublethal doses as larvae. This need is derived from the findings of tests carried out in the first phase of the project, which indicated a drastically impaired flight performance of these animals.
4.3 Ecological investigations
Given the economic exigencies, more extensive investigations on the sizes of the hopper bands, their migrations and food consumption are necessary. Based on the preliminary results from the years 1993 and 1994, many of the control measures routinely carried out until now would appear to be superfluous. Moreover, directly targeted treatments taking into consideration behaviour and the influence of predators could result in substantial savings of insecticide and, thereby, further reductions in cost. Having said that, further investigation is also required into these and related issues-
4.4 Planned cooperations
The stations in Akjoujt and Kiffa are both equipped for simple physiological and entomological experiments, and can also be used as a base for field tests. From Kiffa, both S. gregaria breeding grounds and regions infested with grasshoppers can be easily reached. Using this station, the following cooperations are planned:
a) Hopper band treatments with botanicals and fungal spores in collaboration with LUBILOSA and BBA Darmstadt.
b) Observation, quantification and natural reduction of hopper bands, as well as the influence of predators, together with FAO-LOCUSTOX, Dakar, and FAO.
c) Organisation and quantification of control measures with representatives of the Force Maghrebine and FAO.
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