THE RELATION OF HUMIDITY AND TEMPERATURE TO THE DEVELOPMENT OF THREE SPECIES OF AFRICAN LOCUSTS-LOCUSTA MIGRATORIA MIGRATORIOIDES (R. & F.), SCHISTOCERCA GREGARIA (FORSK.), NOMADACRIS SEPTEMFASCIATA (SERV.)

Author(s):  
Andrew G. Hamilton
1966 ◽  
Vol 70 (672) ◽  
pp. 1077-1081
Author(s):  
D. Yeo

The crops of every continent of the world have been devastated from time to time by locusts or grasshoppers. To mention three major locust species, the Desert Locust (Schistocerca gregaria Forsk.) has caused havoc in a broad band of the world stretching from East Pakistan to Senegal and from the Mediterranean to Central Africa, the Red Locust (Nomadacris septemfasciata Serv.) has infested East, Central and Southern Africa, and the African Migratory Locust (Locusta migratoria migratorioides Rch. and Frm.) has plagued most of Africa south of the Sahara.What happens in one part of a plague area can significantly affect the situation in others and locust control is therefore an international problem, requiring international co-operation. Many of the threatened areas are countries where standards of living are not high and local agriculture is a mainstay of the economy; the regions are often inhospitable and lack modern roads, aerodromes and lines of communication.


1974 ◽  
Vol 64 (3) ◽  
pp. 413-420 ◽  
Author(s):  
E. A. Bernays ◽  
R. F. Chapman ◽  
J. Horsey ◽  
E. M. Leather

AbstractThe amounts eaten by Locusta migratoria migratorioides (R. & F.) on seedling grasses was less than on mature grasses in four other Acridids, Nomadacris septemfasciata (Serv.), Chortoicetes terminifera (Wlk.), Melanoplus sanguinipes (F.) and Schistocerca gregaria (Forsk.). Palatability of the young grasses increases with age, becoming maximal 6–10 weeks from the time of germination. Similar preferences were shown by other Acridids. Time-lapse film studies on Locusta showed that not only is less time spent feeding on seedling grasses, but that locomotor activity levels are considerably higher. Survival studies on the same species showed higher mortality on the seedlings as compared with the mature leaves at all stages of nymphal development, while on seedlings no individuals survived to the adult stage. Lipid-soluble materials were removed from seedling leaves with chloroform or acetone and this rendered them more acceptable, while the extract applied to mature leaves resulted in reduced palatability.


The organization of the thoracic and suboesophageal ganglia in the locust is presented to provide a framework into which details of individual neurons can be inserted as information becomes available. Three species were examined, Chortoicetes terminifera (Walker), Schistocerca gregaria (Forskål) and Locusta migratoria migratorioides (Reiche and Fairmaire). The basic plan of the ganglia is similar in all three species. Series of selected sections in transverse, horizontal and sagittal planes are illustrated to show the arrangement of the main nerve fibre tracts and areas of neuropil, and these are described briefly. A guide is given to prominent features that assist in the interpretation of sections in each plane. In the simpler mesothoracic and prothoracic ganglia nine longitudinal tracts are present in each half of the neuromere, and six dorsal and four ventral transverse tracts (commissures) link the two halves. Four vertical or oblique tracts are conspicuous, the T-tract, ring tract, C-tract and I-tract. Major roots of each peripheral nerve useful as landmarks are numbered from anterior to posterior. Two regions of fine fibrous neuropil are prominent, the ventral association centre and an area associated with the ring tract, a little above it. In the metathoracic ganglion three abdominal neuromeres are fused posteriorly to the true metathoracic neuromere. All four neuromeres show modification of the basic framework chiefly in the arrangement of the ventral commissures and the degree of development of the ventral association centre. In the suboesophageal ganglion three neuromeres, mandibular, maxillary and labial, are fused together from anterior to posterior. They show increasing modification of the basic plan anteriorly. Additional anterior longitudinal tracts are present, which connect with the brain, the dorsal commissures are much reduced and compressed, particularly in the mandibular neuromere, and the ventral commissures of all three neuromeres differ considerably from those of the thoracic ganglia.


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