Radar-based studies of the migratory flight of grasshoppers in the middle Niger area of Mali.
ABSTRACT Some grasshopper species are pests of subsistence agriculture in the Sahelian zone of West Africa. Formulation of effective control strategies against these pests requires some knowledge of their migratory ability. In this paper a study is described in which radar was used to observe aspects of the nocturnal migratory behaviour of grasshoppers in the middle Niger delta. Mass take-off at dusk, layering and common orientation were regularly observed. Layering appeared to be related to air temperature. Mean orientation was often downwind but at other times crosswind headings occurred which added to the southerly component of the insects' displacement. Probable source areas of insects overflying the radar were identified by calculations of the insects' back-trajectories.
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ABSTRACT: SUMMARY (1) On the night of 21-22 October 1978, a dense concentration of grasshoppers overflew one radar in the Tilemsi Valley in Mali, and 2 hours later, was detected passing over the second radar site 100 km to the south. (2) It was very probable that Oedaleus senegalensis formed the major component of the overflying concentration. A larger species (probably Catantops axillaris), and a group of smaller species (probably including Acrotylus longipes, Aiolopus simulatrix and Ochrilidia spp.) also contributed. (3) This flight was an example, albeit a spectacular one, of the southward migrations from the northern Sahel undertaken by Oedaleus senegalensis and other grasshoppers at the end of the rainy season on the north-easterly or northerly winds in the wake of the retreating Intertropical Convergence Zone (ITCZ). The present observations provide direct evidence of the long-range nature of some of these flights. (4) The 0. senegalensis studied engaged in a post-teneral migration. In females, flight activity diminished with the onset of vitellogenesis. (5) The grasshopper concentration was associated with a line of wind-velocity change of unknown origin. The horizontal convergence associated with this wind-shift would produce a concentrating effect on the flying insects. (6) The altitude and timing of flight of the migrating grasshoppers resulted in a displacement largely determined by the wind. (7) The insects in the overflying concentration showed a mean orientation towards the downwind directionJournal of Animal Ecology 02/1983; 52:167-183. · 4.73 Impact Factor
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ABSTRACT: Aluminosilicate ZSM-5 is produced directly from high-silica zeolite Y or zeolite β by a simple hydrothermal treatment of the alkali hydroxide treated starting zeolite material and without using any structure directing organic agent. NMR and FTIR results clearly suggest that majority of the Al(III) species is present in the framework yielding Brønsted acid sites. Addition of appropriate template such as tetrapropylammonium bromide or tetrabutylammonium bromide directs the formation of ZSM-5 and ZSM-11, respectively. The protonated form of all the ZSM-5 catalysts shows very good catalytic activity for the conversion of methanol to hydrocarbon. Similarly, by taking a titanium grafted zeolite b as a starting material, TS-1 has been prepared. Both Ti K-edge XANES and epoxidation of 1-octene confirms the presence of active Ti(IV) centres in this catalyst.Studies in Surface Science and Catalysis - STUD SURF SCI CATAL. 01/2004; 154:758-762.
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ABSTRACT: The paper discusses the development of an unmanned aerial vehicle (UAV) based optical system for tracking individual Australian plague locusts. Managing and monitoring of locust swarms is important for minimising damage to agriculture, and the optical tracker combines the benefits of aerial photography and tagged insects to help with this process. Optical transponders are attached to the upper thorax of individual locusts which are then tracked by a UAV mounted optical tracker. The paper analyses features of each component of the tracker and transponders, critical for the successful operation of the system and verifies them experimentally.Australasian conference on robotics and automation ACRA., Sydney, Australia.; 10/2009