Biology of Sitotroga cerealella (Oliv.) (Lepidoptera: Gelechiidae) reared on five corn (maize) genotypes
ABSTRACT Laboratory experiments under controlled conditions of 30 ± 1 °C, 60 ± 10% r.h. and 14 h photophase were performed to study the biology of Sitotroga cerealella (Oliv.) reared on five natural diets of different corn (maize) genotypes. S. cerealella reared on the shrunken2 genotype displayed the longest developmental time (43.5 d) and the lowest fecundity (85.2 eggs/female). Although the egg to adult developmental time (40.2 d) of S. cerealella reared on sugary-opaco2 did not differ significantly from those on normal, opaco2 and sugary, the survival of the pre-imaginal stage (42.2%) was significantly reduced on this genotype. Significant differences were not found between the number of eggs hatched from females reared on these genotypes. The egg hatch ranged from 86.8 to 95.3% for the shrunken2 and opaco2 genotypes, respectively. Further rearing studies to determine the effects of these genotypes on the biology of S. cerealella are needed, since significant differences were not observed in the data from two successive generations.
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ABSTRACT: Laboratory studies were conducted to determine the effect of threshing different sorghum cultivars on Sitotroga cerealella (Oliv.) and Sitophilus oryzae (L.). In a no-choice test, data on progeny production, loss in grain weight, duration of development, and cultivar index of susceptibility indicated that both species of insect responded differently when bred on unthreshed and threshed sorghum grain. On the average, unthreshed sorghum was more suitable than threshed sorghum for the development of S. cerealella, whereas threshed sorghum was found to be more suitable than unthreshed sorghum for S. oryzae development. Threshing did not have any influence on loss in grain weight due to the feeding activities of the larva of S. cerealella, but S. oryzae caused considerably greater loss to threshed than unthreshed sorghum grain. The duration of development of both species of insect was not affected by threshing, but cultivar index of susceptibility was. The different sorghum cultivars had a significant effect on the performance of both S. cerealella and S. oryzae, indicating that some factors in the cultivars and in the insects themselves were responsible for the observed variation. In a free-choice test, where unthreshed and threshed sorghum grain was exposed to S. oryzae in the same chamber, more progeny were produced in the threshed than unthreshed sorghum.Journal of Stored Products Research. 01/1990;
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ABSTRACT: Four populations of Sitophilus (S. zeamais Motsch. from Mexico, S. zeamais from Arkansas, U.S.A., S. oryzae (L.) and S. granarius (L.) were studied. Hard red winter wheat (“Cloud” variety), brown commercial sorghum, and yellow and white “dent” maize (mixed varieties) were used to determine the effect of parent-and progeny-rearing media on the adult elytron length in each population. Kernel weight loss caused by individuals of each population and weevil weights were determined.Elytron lengths of S. oryzae progeny were significantly (P < 0.05) but only slightly longer, when parents were reared in wheat rather than sorghum or maize; otherwise parent-rearing medium had no effect. Progeny-rearing medium, not parent size, was most responsible for differences in elytron lengths. S. granarius progeny from wheat were significantly larger than those from maize or sorghum; progeny from all other populations were significantly larger from maize than from wheat or sorghum.S. oryzae caused less weight loss in kernels of wheat and sorghum, and were significantly lighter (P < 0.05) than other insects. The Arkansas S. zeamais was significantly heavier than Mexican S. zeamais in wheat, otherwise their weights were similar. Weight losses (actual and percentages) of kernels of all grains were similar for Arkansas S. zeamais and Mexican S. zeamais. S. granarius were heavier and produced greater weight loss in wheat kernels than other populations did.Journal of Stored Products Research - J STORED PROD RES. 01/1985; 21(2):89-93.
- Journal of Stored Products Research - J STORED PROD RES. 01/1985; 21(4):171-178.